Università degli Studi di Pavia
Centro Interdisciplinare di Bioacustica e Ricerche
Ambientali
Ispettorato Centrale Difesa Mare del Ministero dell'Ambiente
International BioAcoustic Council
XV IBAC Conference
Pavia, Italy, October 24th - 26th 1996
Università degli Studi di Pavia
Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
Via Taramelli, 24 - 27100 PAVIA - Italy
Phone/Fax ++39-382-525234
email: web@cibra.unipv.it
http://www.unipv.it/webcib
The abstracts of the conference will be published by the
Journal Bioacoustics
In the meanwhile the abstracts are available
here:
Talks - Posters
List of Participants
TALKS
Acoustic biodiversity in
tropical cicadas: examples from S.E. Asia.
Matija Gogala
Slovene Museum of Natural
History
POB 290, SLO - 61001 Lubljana, Slovenia
Email: matija.gogala@uni-lj.si
It is well known that the
singing cicadas show in S.E. Asia very high biodiversity with many species
inhabiting the same ecosystem. They have to cope with the problem of sending
their acoustic messages in very noisy environment, since many insects,
birds, frogs and other animals are emitting sounds at the same place and
the same period of the year. Therefore the cicadas have developed there
special strategies to cope with the jamming problem. One peculiarity is
the evolution of songs with characteristic rhytmic patterns and in many
cases even with a high degree of frequency modulation. The second adaptation
to the extreme biodiversity is the fixed time of singing. Many cicada
species are acoustically active only during a certain species specific
time period of the day. Such time window is usually 30 to 60 minutes long.
Many species are singing only in the evening or only in the morning hours.
Nevertheless, the dawn-dusk species are in Malayan peninsula an exception.
Such time sharing between different species is probably not the only reason
for "dawn", "dusk" or even "midnight cicadas".
This could also be an adaptation to avoid or minimize predation by birds
or some other insectivorous animals. It should not be overlooked that
many other cicada species there are not limited by a specific time window.
Anyway, in the high biodiversity of S.E. Asia it is not difficult to find
exceptions or special cases, and this is true also for the singing of
cicadas.Therefore, the repertoire of the sound emissions of the S.E. Asian
cicadas is challenging for every sound recordist. With a suitable equipment
nowadays it is not very difficult to make good documentary recordings
there, despite of a high humidity. The main problem is still to see, identify
or even catch the singing animals in the dense vegetation, and to find
out ethological context of recorded sound emission.
Sound libraries have biodiversity
taped.
Richard Ranft
British Library National
Sound Archive, 29 Exhibition Road, London SW7 2AS, UK.
Email: richard.ranft@bl.uk
Between them, bioacoustic
libraries worldwide preserve samples of sounds of most of the vertebrate
species that utilise acoustic communication, and many of the most important
invertebrates. Their collections have been built up mainly through the
contributions of many scientists and recordists and represent many hundreds
of thousands of hours of work in the field. They are invaluable especially
for comparative studies between individuals, populations and species where
it is often impossible for one person to replicate, even in a lifetime
of work, the dedicated efforts of so many collectors of sounds.
Example of the uses of sound libraries in biodiversity studies will be
given, for example: providing identification tools in fieldwork; documenting
biodiversity by sound sampling; analyses of community sound structure
and the "acoustic niche" hypothesis; and as clues for taxonomic
and phylogenetic analyses.
Sound libraries are gradually improving facilities towards proving remote
access to their collections. Preliminary catalogues of two large collections
- those of the National Sound Archive in London and of the Borror collection
in Ohio - are already accessible on the Internet ( <http://mediator.uni-c.dk/paragon/>
and <http://iris.biosci.ohio-state.edu/borror_lab/passerines.html>
) and a small but growing number of Internet sites offer instant access
to actual audio samples.
Acoustic localizations
of blue whales (Balaenoptera musculus) by fixed arrays
and moored autonomous hydrophone arrays.
Kathleen M. Stafford1 , Christopher G. Fox2
1 - CIMRS/PMEL, Newport, OR 97365 U.S.A. Email: stafford@new.pmel.noaa.gov
2 - NOAA/PMEL, Newport, OR 97365 U.S.A. Email: fox@new.pmel.noaa.gov
The Pacific Marine Environmental
Laboratory (PMEL) of the United States' National Oceanic and Atmospheric
Administration (NOAA) has been monitoring and archiving sound recordings
from the U.S. Navy's underwater hydrophone arrays since 1991. These data
contain many marine mammal calls, including those made by blue whales
(Balaenoptera musculus). The call of the blue whale in the northeast Pacific
is often sufficiently loud to be detected on more than one array. Matched
filtering techniques can expand detection capabilities to additional arrays,
allowing blue whale calls to be localized even when they are far from
the arrays.In this manner, PMEL has identified regions where blue whales
occur seasonally well offshore of the west coast of the U.S.
In order to monitor areas of the world ocean not covered by fixed hydrophone
arrays, PMEL has developed autonomous moored hydrophones that have been
used to record acoustic energy from both underwater seismic activity as
well as that from whale calls. Each mooring package consists of an anchor,
an acoustic release, line, hydrophone and data recorder, and a flotation
package. The hydrophones are designed to be moored in the SOFAR channel;
the titanium case containing the data recorder can withstand pressure
to at least 1000 m below sea level. Currently each hydrophone can store
up to 2.8 Gb of data; only the sampling frequency and battery life (up
to 8 months, depending on sampling frequency) limit the duration of the
experiment. The hydrophones are designed to be deployed as an array of
independent instruments whose geometry can be determined by the needs
of the experimenter in order to localize acoustic sources of interest.
Deployment and recovery of each instrument takes as little as one hour
depending upon the platform used.
An array of six of these hydrophones was deployed in the NE Pacific in
September 1995. One of the goals of this experiment was to compare and
"ground truth" locations of calling blue whales from the U.S.
Navy's SOSUS data with those detected on the autonomous hydrophones. During
the seven day experiment, no blue whales were seen in the area but two
blue whales were detected and then tracked acoustically on the hydrophone
array. One of these animals was detected on all three available SOSUS
arrays. The locations of the blue whale from the two methods are comparable
although the location accuracy is more precise on the local array.
Aversive sounds and the
harbour porpoise (Phocoena phocoena).
Goodson A. D., Connelly P. R., Lepper P.
Underwater Acoustics Group - Bioacoustics & Sonar
Electronic & Electrical Engineering Department
Loughborough University, LE11 3TU, UK
Email: a.d.goodson@lboro.ac.uk
In the search for an efficient
acoustic method of reducing the bycatch of porpoises in bottom-set gillnets
the effects of presenting sounds at different frequencies and waveforms
have been examined using a rehabilitated, ex-stranded, harbour porpoise
as the subject in a 20 x 30 m floating net cage experiment. The animal
was available for this study during the last phase of a planned programme
of re-adjustment prior to its release.
Low level sounds SL<130 dB re 1Pa at 1m) were presented underwater
using a purpose built digital signal synthesiser with three types of output:
narrow band tones; wide band frequency sweeps; and click burst sequences
which replicated porpoise echolocation signal characteristics. These signals,
derived from pre-programmed data stored in EPROM, could be clocked out
at different frequencies by binary division of a master clock. This method
produce signals with identical waveforms in a series of octave frequency
steps when divided down from the 140 kHz maximum frequency. The signals
were introduced into the water using 4 simple piezo 'bender' transducers
spaced apart at 3 metre intervals starting at a corner of the net cage
and extending along the longer 30 m side. Surfacing positions were subsequently
extracted from the video camera images which recorded an overhead view
of the pool. The animal's behaviour was studied in 20 minute periods,
i.e. prior to, during, and after exposure to a sound signal, and the results
obtained demonstrate that certain signals caused marked and rapid movement
of the animal to parts of the pool away from the transducers whereas other
sounds had little or no obvious effect. Surprisingly, this animal's choice
of position did not always favour the furthest corner from the transducers.
However, a careful analysis of the acoustic sound pressure field shows
that the complex pattern of sound caused by the 4 interacting sources
produced nulls which the animal was apparently well able to sense and
exploit.
This paper demonstrates the complexity of the sound pressure level variations
that must be taken into account when working in shallow water conditions
especially where constructive and destructive interference can occur between
multiple sound sources and with reflecting surfaces.
Comparison of swimbladder
and pectoral sounds in Pimelodid, Mochokid and Doradid catfishes.
Friedrich Ladich
Institute of Zoology, University
of Vienna, Althanstraße 14, 1090 Wien, Austria
Email: friedrich.ladich@univie.ac.at
Representatives of several
tropical catfish families are unusual among teleosts for having evolved
two sonic organs: pectoral spines for stridulation and swimbladder drumming
muscles. Pectoral mechanisms mainly differ in relative size between pimelodids,
mochokids and doradids, whereas swimbladder mechanisms exhibit differences
in origin and insertion of the extrinsic muscles. In pimelodids, drumming
muscles insert ventrally onto the swimbladder. Mochokids and doradids,
however, possess differing elastic spring mechanisms. Differences in vocalizations
among families were investigated by comparing sounds produced in distress
situations in air and underwater. For each family, fish from two species
were hand-held and their sounds recorded.
High frequency broad-band pulsed sounds of similar duration were emitted
during abduction of pectoral spines in all three families. Adduction sounds
were similar to abduction signals in doradids, shorter and of lower sound
pressure in mochokids and totally lacking in pimelodids. Total pectoral
sound duration was positively related to relative spine length (normalized
for standard length). Simultaneously or successively with pectoral sounds,
low frequency harmonic drumming sounds were produced by representatives
of two families. Drumming sounds were of similar intensity as stridulation
sounds in pimelodids, fainter in doradids, and not present in mochokids.
Swimbladder sounds were frequency modulated and the fundamental frequency
was similar in pimelodids and doradids..
The ratio of stridulatory to drumming sound amplitude was higher in air
than underwater in both doradids and one of the pimelodids. Also, overall
duration of pectoral sounds, compared to swimbladder sounds, was longer
in air than underwater in one doradid and pimelodid species.
This first comparison of vocalizations within one major teleost order
indicates that differences in morphology of swimbladder and pectoral sonic
mechanisms result in family-typical patterns of sound production. Furthermore
differences in sound production between both media suggest that additionally
context- (receiver-) dependent variation in vocalization exists.
Use of auditory brainstem
response (ABR) for fish auditory sensitivity study.
Hong Y. Yan, Todd N. Kenyon, Friedrich Ladich
School of Biological Sciences, University of Kentucky
101 Morgan Building
Lexington, KY 40506-0225, USA
Email: hyyan00@pop.uky.edu
Traditionally psychoacoustical
or electrophysiological methods have been used to study the auditory sensitivity
of fishes. No invasive procedures are used in obtaining behavioral audiograms.
The training procedures involved are tedious, time consuming and not applicable
to every species. Electrophysiological recordings from auditory nerves
or endorgans (e.g., microphonics) provide additional ways of auditory
sensitivity assessment. Technical difficulties and limited sampling site(s)
prevent rapid and complete understanding of fish hearing ability. In an
attempt to expedite the fish audition ability research, an auditory brainstem
response (ABR) recording protocol is developed to provide measurements
of hearing ability of several species of fish. The ABRs represent far
field potentials generated by the hearing endorgans, fiber tracts and
nuclei of the ascending auditory pathway. Therefore audiograms generated
by ABR technique can provide a quick and more complete understanding of
fish hearing ability.
Tungsten reference electrode is placed in between nares of fish while
the recording electrode is placed on the top of fish head to conduct ABR
recording. The fish is immobilized with an injection of Flexedil and a
gravity-feed respirator (with aerated water) is used to keep fish alive
during the recording. Pure tone bursts (100 Hz to 3 kHz) or click signals
are provided through a speaker mounted above the tested animals. A hydrophone
is placed adjacent to the ear region of the fish and traces of hydrophone
output (i.e., the sound likely perceived by the fish) are used to compare
with ABR waves generated by the fish. For comparison purpose fish species
used are a hearing specialist (fathead minnow, Pimephales promelas),
a generalist (oscar, Astronotus ocellatus) and a labyrinth fish
with an accessory hearing enhancing structure (blue gourami, Trichogaster
trichopterus). Easy setup of ABR recording devices and commercially
available systems (e.g., Tucker-Davis Technologies) facilitate quick ABR
measurement of the auditory ability of fishes. This technique can be used
to investigate the relationship between acoustic signals generated by
sonic fish and their auditory sensitivity.
Eavesdropping in a territorial
songbird communication network: preliminary results.
Peter K. McGregor1,2, Torben Dabelsteen2, Jo Holland2
1 - Behaviour & Ecology
Research Group, Department of Life Science,
University of Nottingham, Nottingham NG7 2RD, U.K.
Email: PLZPM@pln1.life.nottingham.ac.uk
2- Department of Population Biology and Centre for Sound Communication,
Zoological Institute, University of Copenaghen, Tagensvej 16, DK-2200
Copenaghen N, Denmark.
Bird song is capable of transmission
over distances of several territories, therefore signallers and receivers
constitute a communication network. Eavesdropping is a type of receiving
behaviour that is only possible in communication networks; it is defined
as extracting information from interaction between other individuals.
Such receiver behaviour has the potential to provide information on relative
competitive ability. In the context of territory defence and bird song
this means that an individual can, by eavesdropping, use its neighbours
as yardsticks against which to judge unknown intruders before having to
interact with those intruders.
We used interactive playback with male great tits Parus major to
simulate a singing intrusion with a subject's neighbour, we then simulated
an intrusion with the subject. Interactive playback was used because it
allows the playback stimulus to be varied song by song and therefore we
could behave as different types of intruders. We signalled willingness
to escalate by overlapping the neighbour's songs and increasing strophe
length relative to the neighbour (song type was matched). We signalled
unwillingness to escalate by alternating playback and reducing playback
strophe length (again, song type was matched).
If subjects had extracted information from the interaction between their
neighbour and playback (i.e. if eavesdropping had occurred) we would expect
the subject to respond differently to the intruder depending on its apparent
willingness to escalate. The first results from such experiments (6 males)
show just such a difference. When subjects were subsequently presented
with "neutral" interactive playback (same song type as used
by the intruder, alternating pattern of singing and matching strophe length)
they responded by overlapping song and remaining at some distance to intruders
which had signalled willingness to escalate with their neighbours. In
contrast, they responded by quickly approaching closely to intruders which
had apparently been unwilling to escalate with their neighbours. This
difference in response is best interpreted as subjects using information
on the fighting ability of the intruder to modify the level of their aggressive
response. They rapidly escalated to close-range territory defence with
apparently weak opponents, but responded more cautiously to apparently
strong opponents.
These results are consistent with eavesdropping and support our contention
that such behaviour will be an important feature of receiving in a communication
network.
Discrimination of the parental
call by the king penguin chick Aptenodytes patagonicus:
the "cocktail-party" effect.
Thierry Aubin1, Pierre Jouventin2
1 - NAM-CNRS URA 1491. Universite
Paris-Sud. F-91400 Orsay, France.
Email: Thierry.Aubin@ibaic.u-psud.fr
2 - CEBC-CNRS UPR 4701. Station de Chize. F-79360 Villiers-en-Bois, France.
The king penguin breeds without
a nest in colonies of several thousands birds. To beg for food, the chick
must recognise the parents in a noisy environment, without using visual
and olfactory, only vocal cues. The parental call has to be distinguished
from among the calls of other parents and chicks and the display calls
of mating pairs. This recognition process is made more difficult not only
by these parasitic noises but also by propagation problems due to the
parent-chick distance and to the mass screen of birds which together impose
a particularly difficult problem of acoustic communication. To study this
recognition process, we have quantified some of the problems which the
chick must solve. Firstly we described the main characteristics of parental
calls. Secondly we measured the ambient noise of the colony in the feeding
area. Thirdly, in this area, we studied the propagation of adult calls
to analyse the degradation of the signal at different distances, quantifying
the effect of the mass body screen by comparison with propagation in an
open area. Then, we conducted experiments with chicks, establishing mean
and maximum distances of detection of the parental call and testing their
ability to detect parental calls in a &laqno; jamming » situation,
i.e. among extraneous adult calls. At last, we tested chicks to determine
which are the main acoustic parameters involved in the recognition process
of the parental call.
Our results demonstrate that the noise in the colony is almost continuous,
that it has a high sound pressure level and that the spectrum is occupied
by numerous birds at a time. There is total masking effect in terms of
frequency and amplitude, increasing the difficulty the chick has in detecting
its parents. Nevertheless, the chick can compensate for this effect, since
it is able to detect an information-carrying signal whose intensity is
below that of a background noise with similar temporal and spectral characteristics.
This process of perception against a background noise (i.e. the &laqno;
cocktail-party effect) is linked to a coding - decoding of the parental
call closely adapted to these particular environmental constraints.
Dialects in Ravens: New
aspects of an old problem.
Peter Enggist
Zoological Institute, University
of Bern
Arbeitsgruppe Ethologie und Naturschutz Laenggasstr. 27
CH-3012 Bern, Switzerland
Email: enggist@aen.unibe.ch
Several studies showed that
male songbirds react differently to songs of the own, adjacent and foreign
dialect. Because reactions to neighbour's and stranger's song of the same
dialect were not compared, and because it was not controlled for structural
similarities among the tested songs, the interpretation of the differences
in reaction remains difficult. It might be that discrimination between
alien and foreign dialects is not principally different from the well
known discrimination between songs of neighbours and strangers, but might
be explained by reacting to differences in structural similarity between
the songs. Therefore Falls (1982) speculated that neighbour - stranger
discrimination would be weak compared to the discrimination between dialects
because dialects are more differing in structure than the vocalisations
of neighbours of the same dialect. We tested this hypothesis on ravens
(Corvus corax) male repetitive calls. Detailed analysis of the
vocal repertoire of 37 resident pairs and the geographic distributions
of the call types showed that two repetitive call types of males and two
of females separate the study area in two dialect regions. Playback experiments
were conducted on males of one of the dialect regions. They reacted differently
to neighbour's and stranger's calls of the same dialect, but not differently
to calls of the adjacent dialect. Whereas calls of the two dialects are
clearly structurally different, neighbour's and stranger's calls within
the same dialect are not differing in structural similarity. These results
indicate that there is not a tight relationship between signal structure
and meaning in the sense that the more differing the signals, the more
differing also the reactions, as has been assumed so far. To interpret
our results and to get on in our understanding of communication in general,
we propose a shift in the point of view from looking at signals and at
the reactions on them as properties of individuals alone to one considering
them as elements of a relationship between individuals.
Communication in Ravens:
Again new aspects of an old problem.
Ueli Pfister
Zoological Institute, University
of Bern
Arbeitsgruppe Ethologie und Naturschutz Laenggasstr. 27
CH-3012 Bern, Switzerland
The development of song in
most songbirds depends upon learning processes.
Only a few studies revealed the possibility that not only vocalisations
might be learned, but also how to use them. We investigated the use of
calls in interactions of 21 resident pairs of ravens (Corvus corax)
and asked whether the use of calls depends on the call types. In our study
area southwards of Bern (Switzerland) we found at 37 resident pairs 81
different call types. The repertoire of an individual male or female raven
contains 12 call types in the mean. Therefore the repertoires are only
partially overlapping. In an experimental setup we provoked interactions
between a free-living and a caged pair. The sequences of calls of the
free-living pair were analysed with row-wise matrix correlations and the
results depicted with correspondence analysis. We found in all pairs a
correlation between the transition matrices of preceding and following
calls of the partners which shows that the call behaviour of one individual
influences that of the other. Therefore the partners are communicating.
Comparing transition matrices of certain call types of different pairs
we found in some cases a high correlation between matrices of different
call types, in other cases no correlation between matrices of the same
call type. Comparing the results of the correspondence analyses among
different pairs, we found that the same call types can be differently
associated with the calls of the partner, although according to the repertoire
composition the same associations would have been possible. This shows
that certain pairs may use one and the same call type differently, and
different call types the same way. How to use a call is therefore not
dependent upon its type or acoustic structure. We conclude that acoustic
communication in ravens is based mainly on conventions between the individuals.
If not only the vocalisations are learned, but also how to use them in
interactions, theoretical concepts of communication, which today assume
that meaning relies on signals, have to be extended to include the possibility
that the meaning of signals depends on relationships between individuals.
Subharmonics, biphonations
and frequency jumps in the vocalisation of Japanese macaques (Macaca
fuscata).
Tobias Riede, Günther Tembrock
Humboldt Universität Berlin,
Fachbereich Biologie, Invalidenstrasse 43, Berlin 10115, Germany
Subharmonics, frequency jumps
and biphonations are well described as normal elements of the human vocal
repertoire. They were found also in the vocalisation of many other mammals
such as the Japanese macaques.
In this work the repertoire of the Japanese macaques was quantitatively
analysed for the occurrence of subharmonics, biphonations and frequency
jumps. These phenomena are summarised as irregularities. Calls from animals
of two established caged groups were recorded, analysed and judged on
the existence of irregularities. In the age class up to 1 year irregularities
occur on average with a frequency of 18.6% (max. 45%, min. 3.5%; 10 infants;
2000 calls). Adult female vocalisation during the mating season ('solicitation
call') contain on average 25% irregularities (max. 32%; min. 15.9%; 6
females; 726 calls). Vocalisations from aggressive encounters (67 calls)
contain no irregularities in adult males and females, but some biphonations
and frequency jumps have been found in the calls of juveniles. The ratio
of the three phenomena shows an individual specific pattern.
Spectrographic analysis
of cat vocalisations during the early months of life.
Clotilde Trinchero, Cristina Giacoma, Roberto Ostellino
Dip. di Biologia Animale,
Università di Torino, V. Accademia Albertina 17, 10123 Torino, Italia.
In a previous study signal
emitted by a mother cat and those emitted by the kittens during the first
weeks of life were compared. It results that the fundamental frequency
of the kitten vocalisation is two or three times the values of fundamental
frequency of their mother. The aim of this study is to describe the harmonic
structure of the signal, the variation of values of the fundamental frequency
during the somatic growth and to study the experimental pattern of Flanagan
(1972). The formant frequencies depend, in a complex way, on the dimensions
and the shape of the vocal tract.
The contact vocalisations (mews) were elicited removing kittens from the
mothers. The vocalisations of four different families of cats were collected
and analysed from the second day up until the 7th month of the kitten's
lives (total number of kittens=13). Records were collected with an analogic
tape recorder (Marantz CP 230) and two digital ones (Aiwa HD-S1 and Casio
DA-1); connected microphones were Sennheiser ME88. Vocalisations were
analysed with the program Voxys implemented in a IBM compatible computer
equipped with a 16 bit Sound Blaster card. The fundamental frequency of
each vocalisation is computed obtaining the T0 period by cepstrum analysis
in the point of maximum stability of the signal. This is obtained searching
the zone of temporal stability during the emission of the sound in three
subsequent frequency bands. The formants are obtained by cepstral analysis
of the spectrum in the point of maximum stability.
Comparing kittens' mews with those of the mother it is evident that during
the early weeks of life, the fundamental frequency (F0) of the kittens'
vocalisations is from 2 to 3 times the fundamental frequency of their
mother's. For each signal of the kitten the value of F0 decreases as a
mean trend with age, while it is constant in each signal of an adult cat.
When the kittens are 60 days old the F0 is comparable to their mothers'
F0 (the maximum difference recorded is 80 Hz). The ratio among the first
three formants is 1:2:3. According to Flanagan's model this ratio indicates
that the shape of the vocal tract is similar to a cylinder with aboral
extremity open.
The measurements of F0, F1, F2 and F3 allowed to discriminate mother's
vocalisations with 100% correctly classified cases (discriminant analysis:
Wilks lamda; F=.17. 155, P= 0.000). The vocalisations of 15 days old kittens
are correctly classified to their families in percentage varying from
78 to 100%. Similar results are obtained with 30 days old kittens. At
60 days the percentage of correctly classified vocalisations reaches 99%.
Vocalisations of captive
black and white ruffed lemur: stability and mother-offspring comparison.
Clotilde Trinchero, Cristina Giacoma, Marco Gamba, Maura Ampollini
Dip. di Biologia Animale,
Università di Torino, V. Accademia Albertina 17, 10123 Torino, Italia.
The aim of this research
is to study the ontogenesis of black and white ruffed lemur (Varecia
variegata variegata) vocalisations by comparing the signals emitted
by a mother with those emitted by her offsprings in order to estimate
the relations between them.
The lemurs live in captivity at "Parco Natura Viva" in Pastrengo
(VR- Italy), in a structure consisting of indoor and outdoor sections
(cages are respectively of 3.00 x 3.00 m and 5.00 x 5.00 m). The studied
group is formed by a pair and their offspring (a young female born in
1994 and one born in 1995; a male born in 1996). The vocalisations of
the male (1996) and the female (1995) offsprings were collected and analysed,
starting from the first days of life until six and 18 months old.
The vocalisations were recorded by analogical recorder Marantz CP 230,
DAT recorders Aiwa HD-S1, Sony TCD-D7, Aiwa PRO HS77; connected microphones
were Sennheiser ME88 and ME66, Trevi ME-27, Shure Studio 1.1. Vocalisations
were analysed with Macintosh IIci computer using Sound Designer IITM and
Canary 1.1.1 programs and IBM compatible computer using Voxys program
suitable to provide the formants.
The analysis has been focused on the "mew", a low amplitude
call emitted by new-borns as well as adults (Pereira et al. 1988). Preliminary
results based on sequential analysis of behaviour preceding and following
the "mews" clearly show that the "mews" are always
emitted in a relaxed situation or social interaction. The "mews"
emitted by the young female are followed by the offspring approaching
her mother only in 1.2 % of cases and they elicit mother approaches in
13.0% of analysed sequences.
The full description of sound characteristics is based on the description
of spectrogram, spectrum and waveform plates. The tonal call exhibited
15-20 weak harmonic bands and a slow rise in pitch. The mean F0 of the
female 1995 regularly decreases from the second day of life up until the
166th day. From that moment until 14 months old varies from 230 to 232
Hz depending on the day. Her mother (5 years old) has a mean F0 of 232+-13.
The fundamental frequency and the first formants show the same trend.
The mean call length tend to be shorter on the first days of life (range
112-582 msec) and become stable (700-800 msec) before the third month
of life. Adult call length varies from 700 to 850 msec length. The amplitude
pattern of the first 4 formants show a decreasing trend. The first one
exhibits the highest amplitude also in new-borns. The energy distribution
of the other formants become stable over the first 5 months of life.
The role of female choice
in the evolution of the European green-toad advertisement call.
Sergio Castellano, Cristina Giacoma
Dip. di Biologia Animale,
Università di Torino, V. Accademia Albertina 17, 10123 Torino, Italia.
In many species of frogs
and toads acoustic communication is the most relevant way by which correct
syngamy is achieved. In these species females respond phonotactically
to the typical stereotyped vocalisations produced by conspecific males.
Moreover, many studies have proved that females are able to discriminate
among conspecific males and select those uttering the most appealing calls.
In the present work we employ the advertisement call of the European green-toad
(Bufo viridis) as a model to analyse the role of female choice
in the evolution of the acoustic signals. Green toad advertisement calls
are described on the basis of four acoustic properties: note and internote
duration, pulse-rate and fundamental frequency. Female preferences for
these same properties are analysed by means of playback experiments, in
which pregnant females have to choose between two synthetic calls that
differ in only one of the previously mentioned acoustic properties. The
analysis of the within-bout of calling coefficients of variation permits
the distinction between highly stereotyped (pulse-rate and fundamental
frequency) and highly variable (note and internote duration) acoustic
properties of the advertisement calls. Females exhibit patterns of preferences
that result in a stabilising or weakly directional selection on stereotyped
properties and in a strong directional selection on highly variable (or
dynamic) properties of the calls. The observed relationships between signal
variability and pattern of female preferences support three hypotheses:
1) different acoustic properties of the signals encode different kinds
of biologically significant information; 2) since a high stereotypy of
the signals (high redundant information) is known to reduce the risk of
communication errors, the high stereotypy of some acoustic properties
can be seen as an adaptive character connected to their function of species-specific
information encoders; 3) female preferences and the different selective
pressures acting upon the acoustic properties of the calls can be seen,
together with some developmental constraints, as the most relevant forces
in the evolution of the green toad communication system.
First record of the mating
call of a burrowing frog from western Madagascar: Scaphiophryne
brevis (Boulenger, 1896) (Anura: Microhylidae).
Riccardo Jesu, Giovanni Schimmenti
Acquario di Genova
Area Porto Antico, Ponte Spinola
I - 16128 Genova, Italia
The Anurans of Madagascar
include about 170 species grouped in three families: Hyperoliidae, Ranidae
and Microhylidae. The endemism rate at species level is around 99%, since
only two species belonging to the Ranidae are not endemic to the island.
The subfamily Scaphiophryninae is an endemic taxon of the Microhylidae
which has been divided in two genera: Paradoxophyla Blommers-Schlösser
& Blanc, 1991 (monotypic) and Scaphiophryne Boulenger, 1882
(five species).
Scaphiophryne brevis (Boulenger, 1896) is a very poorly known burrowing
frog from western and south-western Madagascar inhabiting dry open habitats,
most of them consisting in secondary vegetation types.
During fieldwork carried out in the peak of the rainy season (January
1995) in a coastal area of the west, a group of calling males of Scaphiophryne
brevis was observed near shallow temporary ponds in sandy soil located
a few dozen metres from the shore within Morondava village. This gave
the opportunity of recording for the first time the mating call of this
species one century after its description.
The call - recorded at an air temperature around 25 °C - consists in the
monotonous repetition of an inharmonious note lasting 340-350 ms between
interval of 400-510 ms. Frequency ranges from 2 to 5.5 kHz.
It may be interesting to compare the call of this species to the one recorded
from Scaphiophryne calcarata (Mocquard, 1895), another burrowing
frog apparently closely related to Scaphiophryne brevis and found
in similar habitats. The mating call of Scaphiophryne calcarata -
recorded in Tolagnaro, south-east Madagascar, at 25 °C - consists in the
repetition of a screaming sound which lasts 850-900 ms and is repeated
after 2200-2500 ms. Frequency ranges from 3 to 4.3 kHz.
A bionic sonarhead.
Herbert Peremans, Ashley Walker, John Hallam
Artificial Intelligence Department, University of Edinburgh
Forrest Hill 5, EH1 2QL Edinburgh, UK
Email: herbertp@aisb.ed.ac.uk
We will present a 5 DOF ultrasonic
sensorhead that allows the study of different sensor-motor loops in echolocation.
The head consists of a neck, allowing for the panning of the head as a
whole, a transmitter which is fixed to the head and two independently
orientable receivers, one on either side of the transmitter. Each receiver
has two DOF allowing for pan and tilt movements around its centre. The
generation of the transmit signal, the processing of the received signals
as well as the motorcontrol of the sensorhead is executed on a transputer
network. To process the received signals we make use of a filterbank modelled
on the bat's cochlea. This filterbank consists of a number of bandpass
filters logarithmically distributed over the frequency range of interest,
currently from 30 kHz to 100 kHz. The shape of these filters and the distribution
of their central frequencies can be varied depending on the specific echolocation
task being investigated. Next we determine the instantaneous amplitudes
of the outputs of these filters by a rectification and low-pass filtering
process. We believe that although this is only a crude approximation to
the actual processing performed at the cochlear level it nevertheless
succeeds in modelling the cochlea's most important characteristics. The
outputs of this model are the inputs for the different echolocation tasks
we want to study. The head is now being used to investigate what clues
are available to a binaural animal while tracking a prey. We also look
at the robustness of the different tracking schemes in the presence of
clutter. It is clear that the head allows the study of many other mechanisms,
especially those involving sensor-motor interaction, important to echolocation.
Hence, we argue that bionic devices such as our sensorhead are valuable
tools adding to the instrumentarium of those that study echolocation by
biological organisms.
Ultrasonic vocalizations
during eterosexual encounters in mice.
Mazzacane E., D'Amato F.R.
Istituto di Psicobiologia
e Psicofarmacologia, C.N.R., Via Reno 1, 00198 Roma, Italia
Email: damato@vaxiac.iac.cnr.rm.it
Ultrasounds are emitted by
mice in different social contexts. The main interest has been devoted
to ultrasounds emitted by pups during their development that seem to affect
mother-infant relationship. They have been used as a measure of stress
that can be easily pharmacologically modulated. Adult mice emit ultrasounds
during the first minutes of interaction with a potential sexual partner.
Mainly the male seems responsible for these vocalizations and data from
the literature suggest that these calls represent a measure of male sexual
motivation.
Several experiments have been conducted to verify this hypothesis. NMRI
outbread albino mice were tested for ultrasonic emission during the first
three minutes of sexual encounters.
Ultrasounds (70 + 5 kHz) were counted by the use of a bat detector
(QMC Instruments). Female characteristics (strain, weight, estrous condition)
did not seem to affect male ultrasonic emission. Genetic and experiential
male's characteristics did not represent variables affecting, from a quantitative
point of view, males ultrasonic calls.
We did not find significant correlation between ultrasonic vocalization
(UV) and latency of ejaculation nor between male behaviours indicating
strong arousal and UV. On the contrary we found a strong inverse relationship
between aggressiveness and ultrasonic vocalisation: males with little
UV towards females showed more male-male aggressiveness than males with
high vocalisations. The amount of ultrasonic calls seemed rather affected
by the test cage while not the behaviours: testing the male in the presence
of the odour of another male sensibly decreased UV. Moreover, when females
were given the opportunity to choose between beddings of males with low
and high levels of UV, diestrous females preferred the bedding of high
vocalizing males while estrous females did not show clear preference.
All together these data raised doubts about the causal and functional
implications related to ultrasonic communication during the first minutes
of sexual interaction.
Sonographic characterization
of ultrasonic vocalizations emitted by infant laboratory mice.
Igor Branchi, Daniela Santucci, Augusto Vitale, Enrico Alleva
Section of Behavioural Pathophysiology
and Section of Comparative Psychology, Laboratorio di Fisiopatologia di
Organo e di Sistema, Istituto Superiore di Sanità, Viale Regina Elena
299, I-00161 Roma, Italy
Email: fosmail@dns.istsan.interbusiness.it
Young mice and rats separated from the mother and littermates produce
ultrasonic vocalisations during the first two or three weeks of postnatal
life. Various conditions such as handling, hypothermia, olfactory or tactile
stimulation elicit ultrasonic emission from the immature rodent. These
vocalisations are also affected by either changes in social variables
or by administration of psychoactives.
Although it is known that pup vocalisation stimulate a prompt expression
of maternal behaviours such as nest-building, searching, and retrieving,
the communicative role of infant ultrasonic vocalisations is still a matter
of investigation. A fine-grained analysis of ultrasonic vocalisations
per se, as well as the study of the different contexts in which calls
are emitted, may contribute to a better understanding of their possible
role in adult-infant intraspecific communication.
Eight-day-old outbred CD-1 mice were isolated from their mother and littermates
and randomly exposed to one of the five different experimental conditions,
namely: i) odour from the nest; ii) social isolation; iii) low temperature;
iv) tactile stimulation; v) odour from a conspecific adult male.
Spectrographic analysis of the structure of the calls revealed that ultrasonic
calls by neonatal mice are differently shaped (although conforming to
5 main stereotyped types: constant frequency, modulated frequency, frequency
steps, composed, short) and that, when the sound-structure typology and
emission frequency interval are considered, the context under which vocalisations
are emitted strongly influences type and frequency of call production.
Furthermore, the present study helps to better understand the ultrasonic
production behaviour of the mouse, increasingly the most common rodent
species in biomedical laboratories, and it can be highly adequate for
the development of ethological models aimed at teratological or toxicological
investigations. Finally, our results may be useful to the evaluation of
regulatory guidelines (OCSE, WHO, EU, etc.) using functional endpoints
for assessment of early behavioural deficit.
POSTERS
Interactive deterrent devices
for fishing nets, designed to reduce small cetacean bycatch.
Goodson A.D., Newborough D. and Woodward B.
Underwater Acoustics Group - Bioacoustics & Sonar
Electronic & Electrical Engineering Department,
Loughborough University, LE11 3TU, UK
Email: a.d.goodson@lboro.ac.uk
The problems of reducing
small cetacean bycatch in fishing nets are many and complex and acoustic
solutions need to be tailored to suit specific species and net types.
Active deterrent devices or alarms have recently been shown to be beneficial
in reducing the bycatch of harbour porpoises (Phocoena phocoena)
in some carefully monitored trials in North American sink-gillnet fisheries
(Kraus et al. 1995). The methodology employed to date is still at an early
stage of development, typical devices generate simple 10 kHz tonal pulses
from small battery powered packages distributed at intervals along the
fishing net. The long term effectiveness of this approach has already
been questioned as small cetaceans are known to habituate quite quickly
to novel stimuli. A more sophisticated approach is now at the trials stage
which uses higher frequency, wideband signals which have been determined
to be more aversive to this species (Goodson & Connelly, this meeting).
To minimise habituation effects over time such 'beacon alarm' signals
need only be transmitted occasionally if the acoustic activity of an approaching
echolocating animal can also be detected and used to trigger the device
into a transponder type of operation. Such a device has now been designed
at Loughborough University and implemented using digital micro-controller
technology. As this circuitry is programmable almost any complex waveform
can be generated to suit specific applications. The use of a digital micro-controller
permits a number of additional features to be implemented in software
without a significant increase in the overall component count and, despite
the sophistication, the cost per device remains acceptably low.
It may be argued that a silent animal could remain at risk, however, in
the context of bottom set nets (sink-gillnets) this should not apply,
as the harbour porpoise swimming close to the bottom in deep water is
there to forage for prey and hence actively employing its echolocation
sense. This interactive approach reduces spurious acoustic emissions which
waste battery energy and as most responses are triggered by the approach
of an animal at risk of colliding with the net, the deterrent effect is
expected to be longer lasting. The alarm response ceases quickly once
the animal turns away. Provided that these devices are spaced apart along
the net within detection range of each other additional benefit is obtained
if they also respond to a neighbour's alarm signal as this will result
in a 'ripple-fire' of activity along the net. This linking of emissions
provides better orientation information than can be given by simple randomly
timed pingers. Interactive devices are also intended for application to
large pelagic trawls where the delineation of the net's boundary by such
a ripple-fire transmission is expected to give a clearer indication of
the extent of the hazard to an animal which may have followed fish into
the net. Since triggering can also be stimulated by a ship's echosounder
these devices should make the location and recovery of lost nets a relatively
simple exercise.
Underwater acoustic recording
of cetaceans made by the Italian Navy.
Gianni Pavan1,3, Marco Priano1, Michele Manghi1, Pamela Nascetti2, Andrea
Perazzi2
1 - Centro Interdisciplinare
di Bioacustica e Ricerche Ambientali, Università degli Studi di Pavia
Via Taramelli 24, 27100 Pavia, Italia. Email webcib@ipv512.unipv.it
2 - Istituto di Anatomia Comparata, Università di Genova, Italia
3 - Dipartimento di Urbanistica, Istituto Universitario di Architettura
di Venezia, Italia
Within the frame of the European
Nature Conservation Year 1995, the Italian Navy set up a cooperative research
program with Universities and other institutions to give logistic support
and to apply its technologies to the study and protection of the marine
environment. The project includes a research program on cetacean acoustics,
mainly dealing with the sperm whale Physeter macrocephalus, to
unveil and monitor its seasonal movements and behaviour. The Italian Navy
surface vessels crews have been trained to visually recognize them in
order to fill sighting schedules. Besides, personnel working on submarines
and maritime patrol aircraft has been trained in identifying biological
sounds recorded during ASW (Anti Submarine Warfare) operations.
ASW techniques proved to be successful in finding and recording cetaceans;
unclassified sound recordings made independently by the Navy, with surface
vessels, submarines and sonobuoys, have been provided to the Cetacean
Sound Library of the Centro Interdisciplinare di Bioacustica e Ricerche
Ambientali.
The research continued in 1996 mainly with the collection of recordings
from sonobuoys deployed while performing ASW patrolling activities.
To date, several valuable recordings have been collected from elusive
species like the sperm whale and pilot whale. Several recordings of sperm
whale codas typical of the Mediterranean Sea (/// / pattern) have been
collected, including new "short" codas with the same distinctive
pattern.
Whenever possible, species identification of vocalizing animals was made
by comparing sounds with those available in the Cetacean Sound Library.
Acoustic behaviour of a
Bottlenose Dolphin (Tursiops truncatus) mother-calf
pair in captivity: technical aspects in data collection and analysis.
Guido Gnone1, Gianni Pavan2,5, Stefania Manca3, Carla Benoldi4, Barbara
Bonsignori4, Michele Manghi2
1 - Acquario di Genova, Area
Porto Antico, Ponte Spinola, 16128 Genova, Italia
2 - Centro Interdisciplinare di Bioacustica e Ricerche Ambientali, Università
di Pavia, Italia
3 - Istituto di Zoologia, Università di Genova, Italia
4 - Istituto di Zoologia, Università di Milano, Italia
5 - Dipartimento di Urbanistica, Istituto Universitario di Architettura
di Venezia, Italia
For one year, starting on
September 5th 1994, the behaviour of a captive new born bottlenose dolphin
(Tursiops truncatus) and its mother was monitored through both
video and acoustic recordings.
The main objective of such research was to study the behavioural evolution
of the two during the first year of the calf's life. Attention was focused
on acoustic behaviour and its use in relation to the contexts.
In order to be able capture any possible correlation, the acoustic signals
were analysed with a PC based DSP Workstation developed at the University
of Pavia and the resulting real-time spectrographic analyses were superimposed
on the live video recordings.
The poster will present all the technical elements used in developing
such method for collection and analysis of the video and acoustic signal.
Problems related to such system and suggestions for a better output will
also be part of the presentation.
Analysis of long clicking sequences
of Sperm whales (Physeter macrocephalus).
Gianni Pavan1,2, Marco Priano1, Michele Manghi1, Claudio Fossati1
1 - Centro Interdisciplinare di
Bioacustica e Ricerche Ambientali, Università degli Studi di Pavia
Via Taramelli 24, 27100 Pavia, Italia. Email: webcib@ipv512.unipv.it
2 - Dipartimento di Urbanistica, Istituto Universitario di Architettura
di Venezia, Italia
In June 1995, a 12 days research
cruise was organized in the Ligurian and North Thyrrenian Sea to record
cetacean sounds with the towed array of the University of Pavia. The cruise
has been supported by the Italian Navy within the ENCY 95 (European Nature
Conservation Year) activities.
The hydrophone was towed for 111 hours (out of 12 cruising days) at speeds
up to 14 km/h; listening stations were held on a 24h schedule for at least
10 min every half an hour. One sperm whale was detected and located. It
was heard at night and acoustically tracked for the following 8 hours.
Within this period, the whale was sighted at the surface 5 times while
8 complete dives were continuously recorded on DAT tapes (about 6 hours
of recording). The recordings are now archived at the Cetacean Sound Library
held at the Centro.
New methods of sound analysis were developed to make the analysis of such
long recordings easier and to give compact pictures of whole dives. Our
real-time analysis software was modified with new procedures able to 1)
automatically detect and count clicks, 2) measure and save inter-click
intervals, 3) save a packed representations of the click sequences and
display autocorrelograms to show the evolution of interclick intervals
over long periods of time.
The analysis of the recordings shows that all the recorded dives were
characterized by a typical and constant clicking pattern at their beginning.
The duration of the acoustical emission, measured from the first click
to the last click of each dive, was on average 27 minutes 30 seconds while
the silence related to the surfacing was on average 13 minutes and 11
seconds.
Sound production and reproductive
behaviour in the Armoured Catfish Corydoras paleatus
(Callichthyidae).
Inge Pruzskinszky, Friedrich Ladich
Institute of Zoology, University
of Vienna, Althanstraße 14, 1090 Wien, Austria
Sound production during courtship,
dyadic encounters and in distress situations was investigated in C.
paleatus. Fish emitted broad-band stridulation sounds made up of several
pulses. Each sound corresponds to the abduction of one pectoral spine.
The sonic mechanism was developed in all individuals. Males, however,
had relatively longer pectoral spines (standardized to body length) than
juveniles or females.
Several males, which are usually smaller than females, court with one
gravid female at the same time. Courting males emitted trains of sounds
averaging 1250 ms in duration. During spawning one male clasped the female's
barbels with his pectoral spine and inseminated almost all eggs. DNA-fingerprinting
revealed, however, that a few eggs were fertilized by nearby males. Males
did not behave aggressively towards each other during courting or dyadic
encounters. During dyadic encounters males emitted shorter duration trains
of sounds (mean: 850 ms) than during courtship.
Single stridulation sounds were emitted in distress situations, when fish
were hand-held in air. Contrary to courtship and encounter sounds, distress
calls were produced by both sexes and were also recorded from juveniles.
Dominant frequency of sounds was negatively correlated to body weight.
Sound duration was positively correlated to relative size of pectoral
spines.
This description of acoustical behaviour in corydoradine catfish reveals
striking differences to the second callichthyid subfamily (Callichthyinae),
where vocalization was observed during territorial behaviour in males
and aggressive behaviour in both sexes (Mayr, 1987).
Ontogeny of Agonistic Behaviour
and Vocalization in the Croaking Gourami, Trichopsis vittata
(Teleostei).
Silvia M. Henglmueller, Friedrich Ladich
Institute of Zoology, University of Vienna, Althanstrasse 14
1090 Vienna, Austria
Email: a8602315@unet.univie.ac.at
The development of agonistic behaviour
and vocalization in the croaking gourami was studied from hatching to
four months of age, by which time fish became sexually mature. Initial
interactions started when fry were 11 days old and consisted of Approach
and Flight in a feeding context. More complex threat patterns appeared
during dyadic encounters as fish grew older. Lateral Display (spreading
of median fins in a lateral position) first occurred during the third
week, Circling shortly afterwards and Pectoral fin beating when fish were
seven weeks old. Rapid pectoral fin beating was first accompanied by sound
emission at eight weeks. Initially, croaking sounds were built up of a
series of single pulses, each one produced by one pectoral fin. Later
single-pulses gave way to double-pulsed bursts. Mean number of single
and double pulses increased from 4.4 to 6.0 per croak and mean pulse period
from 27 to 35 ms from initial sound production until maturity. Furthermore
sound pressure increased significantly with growth of fish. Dominant frequency
of croaks decreased from 3600 to 1500 Hz with increasing size (15 - 37
mm standard length). After vocalization was established Frontal Display,
Mouth Biting and Appeasement Behaviour occurred at the age of ten weeks.
The development of agonistic behaviour is mainly age and not size dependent
in croaking gouramis, although growth-rates differed widely. Unlike behavioural
patterns sound characteristics were clearly correlated with body size.
To our knowledge this is the first study investigating ontogeny of vocalization
in fish. Results in T. vittata demonstrate that sound production
develops simultaneously with agonistic behaviour patterns and thus independently
of sexual maturation.
Startle response level
of Japanese anchovy Engraulis japonicus to underwater
pure tone signals.
T.Akamatsu,Y.Matsusita,Y.Hatakeyama, Y.Inoue
National Research Institute of Fisheries Engineering,
Hasaki, Kashima, Ibaraki, 314-04 Japan
Email: yhatakey@nrife.affrc.go.jp
Reactions of Japanese anchovies
Engraulis japonicus to 100 to 700 Hz underwater pure tone signals
were observed. A mean body length of the anchovies was 11 cm and a mean
weight was 10 g. Seven hundred fish were kept in a net enclosure which
was 2 m in diameter and 1.5 m in depth.
The anchovies ordinarily swam in a circle at almost same speed in the
net enclosure.
The startle response behavior was defined as follows: more than a half
of the fish changed their behavior just after the sound projection , for
example, the acceleration of the swimming speed, dispertion or condensation
of fish group. When no or few anchovies changed their ordinary behavior,
it was defined as no response.
The up/down staircase method was used to determine the threshold level
of the startle response. The sound pressure level ranged from 130 to 160
dB and was changed by 5 dB step.The startle response levels were 154.5
dB at 100 Hz, 153.3 dB at 200 Hz, 146.8 dB at 300 Hz and 153.8 dB at 500
Hz. The 700 Hz signal did not affect the fish behavior up to 158 dB.
Repeatability and effects
of temperature and individual size on components of the breeding sounds
emitted by males Padogobius martensii (Pisces, Gobiidae).
Marco Lugli
Dipartimento di Biologia
Evolutiva e Funzionale, Viale delle Scienze, Università di Parma, 43100
Parma, Italy
Repeatability, that is the
intra-class correlation coefficient (Sokal & Rohlf, 1981), describes
the degree to which variation within individuals contributes to the total
variation in a group of individuals. In this study the repeatability for
several parameters of the tonal and the drumming sounds emitted by breeding
males of Padogobius martensii was measured to examine (1) which
parameters of the sounds were more repeatable (i.e., stereotyped), (2)
the contribution of temperature and male size to between-male variation
in sound parameters, and (3) the potentiality for individual assessment/recognition
by acoustical means in this species.
Sounds were collected from single bouts of calling by 16 males differing
in body size and water temperature. All the sound parameters examined
showed a remarkable inter-male variability. Water temperature explained
most of between-male variation in the properties of the tonal sound, while
body size was the main factor explaining the between-male variation in
the properties of the drumming sound. After temperature control, however,
the two types of sound showed a similar pattern of variation in the acoustic
properties. Parameters of the tonal sound were less repeatable than their
counterparts in the drumming sound. In general, high repeatability in
a sound parameter was associated with a larger contribution of male size
to the between-male variation in that property (after correction for temperature).
Because of higher repeatability and stronger relationship with male size,
the drumming sound appears to be adapted to convey information about the
quality of the emitter (assessment signal).
Sound production with an
abdominal "tymbal" organ in a noctuid moth, Pseudoips
fagana.
Niels Skals, Annemarie Surlykke, Hanne Sørensen
Centre for Sound Communication,
Inst. of Biology
Odense University, Campusvej 55, DK -5230 Odense M, Denmark
Email: Skals@Biology.ou.dk
Hearing in moths has evolved
to enable them to detect and evade echolocating bats. Thus most moths
are silent. Among Arctiidae click production with tymbal organs on the
metathoracic episternites is fairly common, but in most species this is
also part of the interaction with bats. However, a few moth species produce
sound and use their hearing for intraspecific communication. Generally,
the noctuid species described so far produce sound by some kind of stridulatory
mechanism often involving the wings and legs. Here we describe quite another
mechanism of sound production in the male noctuid moth Pseudoips fagana
(FABRICIUS) of the subfamily Chloephorinae, involving a ventral "tymbal"
organ centrally on the ventral part of the basal abdominal segment. P.
fagana, the green silver line, is common in northern Europe. The sound
production has been observed while the moths fly around the tree tops
in the dusk. The clicks sound like electric sparks to the human ear and
may be heard at several meters distance. We recorded clicks from males
in stationary flight in the lab. The moths would only click while flying
in place. We elicited the clicks by very intense ultrasonic sound pulses.
The moths produce short series of clicks each lasting around 0.3 to 0.4
ms with maximum sound energy around 30 kHz. The sound pressure level was
intense, 119 dB SPL at 2 cm. The sound producing organ is buried deeply
in a groove, but may be observed if the moth is placed ventral side up
and the abdomen is bend dorsally. The hearing of P. fagana was measured
by recording extracellularly from the auditory nerve. Both males and females
were most sensitive around 30 kHz with a threshold of about 35 dB SPL,
thus matched to the spectrum of the sounds. There are no behavioural observations
on these moths, but we believe it most likely that the sounds are part
of the sexual display.
Research supported by the Danish National Research Foundation.
Acoustic emission in Megatrupes
cavicollis (Bates 1887) (Coleoptera, Geotrupinae).
C. Palestrini, M. Luzzatto, A. Roggero, M. Zunino
Dip. di Biologia Animale, Università di Torino, V. Accademia Albertina
17, 10123 Torino, Italia.
The genus Megatrupes
Zunino 1984 is up to now represented by two species, M. cavicollis
(Bates 1887) and M. fisheri (Howden 1987), both distributed between
the Wesyern Sierra Madre and the Sistema Volcànico Transversal, in Mexico.
The aim of our research is to analyze the sound produced by M. cavicollis
through two distinct apparatuses - thoraco-elytral and coxo-abdominal.
The individuals examined were collected during the summer 1987 at the
Reserva de la Biosfera "La Michilia", Durango, Mexico.
Signals were recorded, acquired and analyzed through the program Signalyze
3.12. Each emission is constituted of a disyllabic chirp, with two distinct
subunits separated by a pause. This is a standard situation among the
Geotrupinae.
Seven variables concerning duration and frequencies of the chiro have
been analyzed. The sexual dimorphism, as regard the morpho-anatomy, does
not appear at the acoustic one.
Both apparatuses contribute to the sound production. Nevertheless, the
coxo-abdominal apparatus seems to be more effective than the thoraco-elytral.
Individuals deprived of the elytra emitted stridulations very similar
to those usually produced by individuals not experimentally constrained,
whereas individuals deprived of their hind legs emitted very thin, unrecognizable
sounds.
Although statistical analyses of frequencies and duration show significant
differences among individuals, males and females do not appear to be separated
into two distinguishable clusters.
New data on the acoustic
communication in two mediterranean grasshoppers (Orthoptera, Acrididae).
M.E. Clemente, M.D. Garcia, J.J.Presa
Department of Animal Biology
(Zoology). Faculty of Biology.
Espinardo Campus. University of Murcia. 30100 Murcia. Spain.
Email: mdgarcia@fcu.um.es
New data on the sound produced
by Sphingonotus coerulans corsicus Chopard, 1923 and Truxalis
nasuta (Linneo, 1758) are given. Oscillograms of both sounds are provided
for the first time, as well as their physical characteristics and other
aspects of the communication between specimens.
For both species sound seems to be a territorial and sexual cue; they
have not been observed singing when isolated, as other Acrididae, but
always when they are close to or in contact with other individuals.
The song of Truxalis nasuta consists of isolated echemes composed
of 7 - 29 syllables lasting about 0,234 seconds. The syllable repetition
rate is about 2,2 syllables/sec.
The main frequency of emission is between 1 and 10 kHz, with the main
peak at 5 kHz.
For Sphingonotus coerulans corsicus two different songs have been
recorded, one for a territorial behaviour and other for a courtship one.
The territorial song consists of isolated syllables lasting about 0,350
seconds with the main frequency between 4 and 8 kHz, with a peak at 7
kHz.
The courtship song consists of a syllable produced by the movement of
hind legs followed by several microsyllables produced by light movements
of hind legs. The syllable lasts about 0,670 seconds. Sometimes, after
the sounds referred before, the specimens produce a new syllable, always
shorter than the first, and more microsyllables, but always fewer than
before. The frequency of this song lays between 3 and 5 kHz, with the
main peak at 3 kHz.
* This communication has been partially supported by the D.G.I.C.Y.T.
grant number
PB89-0448 of the Spanish Governement.
Stridulation in four ants
species of the genus Messor: ultrasonic emission
and description of their stridulatory apparata (Hymenoptera,
Formicidae).
Priano M.1, Pavan G.1,4, Mori A.2, Grasso D.2 , Le Moli F.2, Giovannotti
M.3, Fanfani A.3
1 - Centro Interdisciplinare
di Bioacustica e Ricerche Ambientali, Università degli Studi di Pavia
Via Taramelli 24, 27100 Pavia, Italy. Email: webcib@ipv512.unipv.it
2 - Dipartimento di Biologia Evolutiva e Funzionale, Università degli
Studi di Parma, Italy.
3 - Dipartimento di Biologia Animale e dell'Uomo, Università degli Studi
"La Sapienza", Roma, Italy.
4 - Dipartimento di Urbanistica, Istituto Universitario di Architettura
di Venezia, Italy
The aim of this work is to
amplify the knowledge of acoustic communication in ants. Four myrmicinae
species belonging to the genus Messor (i.e M. capitatus,
M. minor, M. structor and M. wasmanni) were tested.
Some Messor species have already been the object of a preliminary
study only on workers (Schillinger and Baroni Urbani, 1985) but in our
work the ultrasonic emission of specimens belonging to the castes of queens,
males and workers (minor and major) were recorded.
Ultrasonic signals were acquired using a Bruel & Kjaer 2231 with a
B&K 4135 transducer (frequency response up to 100 kHz) and a bat detector
Ultra Sound Advice S-25.
Signals were fed into an amplifier with anti-aliasing low-pass filter
to be digitally recorded and analyzed on a PC-based Digital Signal Processing
Workstation. Sampling frequencies up 200000 s/sec allowed the recording
up to 87.5 kHz. The ants were held with a pincer and the microphon was
kept at a distance of approx. 1 cm.
The description and measurements of stridulatory apparata were made by
means of S.E.M. (Scannig Electron Microscope Cambridge S 250 TP) analysis
on the same specimens used for recordings.
In all the individuals investigated, a stridulatory organ occurs in the
position regarded as typical of Formicidae: the plectrum
on the hind margin of the third abdominal tergite and the file of pars
stridens on the pretergite of the fourth.
The file is made up of very regular parallel cuticular ridges and, in
all the individual examined, extends for almost the whole length of the
pretergite itself stopping at a very short distance from the anterior
margin of the pretergite. The pars stridens shows very sharp margins.
Posteriorly, some long bristles occur in proximity of the margins.
The hind margin of the third abdominal tergite shows, in its very central
part, a tickening connected with the scraper. This tickening makes the
scraping action of the tergal margin more effective conferring rigidity
upon this region.
For each species it is possible to describe a common general pattern of
structure and operation of the organ producing sounds and ultrasonic emission
which is always of values in maximum frequency higher than 41 kHz.
Playback tests are in progress in order to clear up the biological role
and significance of the acoustic signalling for the survival of the colony
of these species.
Vocalization structure
and its possible function in the Brown-headed parrot Poicephalus
cryptoxanthus.
Vincenzo Venuto, Renato Massa
Dipartimento di Scienze dell'Ambiente
e del Territorio
Università degli Studi di Milano
Via Emanueli 15, 20126 Milano, Italia
Today there is evidence that parrot
vocalizations and even parrot mimicry are highly functional. In addition,
there are also data suggesting that parrots may be able to use assemblages
of short sounds, normally used in a given context, to built up more complex
vocalizations that may be used in a different context.
To investigate this possibility, we studied vocalizations and associated
behavioural patterns of the Brown-headed parrot (Poicephalus cryptoxanthus),
a South-East African species, kept in pairs in captivity at our African
Parrot Centre of the University of Milan. By analyzing a total of 12 hours
of records by mean of the "Canary" program of Cornell Laboratory
of Ornithology, we recognized seven main types of calls that may be separated
in the following groups: a) short antagonistic calls associated with an
imminent attack or a warning to disperse, b) nestling's calls mainly consisting
in food begging, c) sexual interactions, that is courtship, duetting,
preening and courtship-feeding. The latter are also the longest and most
complicated calls. They are composed of a total of 10-13 syllabes that
may be assembled in different notes that, in turn, may be further assembled
in a song that may consequently be highly variable and may even last for
78 seconds. These long and complicated songs are usually uttered as a
duet by the members of a pair probably to consolidate the ties between
male and female. These findings further support the hypothesis that some
parrots may maintain their monogamic pair-bond through the performance
of a pair specific courtship song that, in some species, such as the African
grey, may also include the mimicry of heterospecific sounds.
Song repertoire variability
in the reed bunting Emberiza schoeniclus.
Giuliano Matessi1, Alessandro Grapputo1, Andrea Pilastro2, Guglielmo Marin1
1 - Dipartimento di Biologia,
via Trieste, 75 - 35121 Padova
2 - I.N.F.S., via Cà Fornacetta, 9 - 400064 Ozzano E. (BO)
The Reed bunting (Emberiza
schoeniclus) is a passerine belonging to the family Emberizidae,
subfamily Emberizinae, largely spread in the Paleartic region,
mainly in marshes and reedbeds. This species includes several forms, grouped
in three main subspecies: E. s. schoeniclus, intermedia and pyrrhuloides.
These differ slightly in size and colour and highly in bill shape and
size. A high intraspecific polymorphism for bill size is rather uncommon
in passerines; it has been shown that this variation is genetically determined
and often involves an extension of the trophic niche.
We analised the genetic and morphologic variation within and among populations
of E. s. schoeniclus ( the small bill, migrant form, that breeds
in central Europe and marginally in north Italy) and E. s. intermedia
( the large bill, mainly resident form, that breeds in several locations
throughout Italy). During winter the subspecies are simpatric in northern
Italy. The separation in bill morphology was reflected in a separation
in genetic variability. We are intersted in finding the forces that could
maintain this separation. One could be a difference in song repertoires.
Models of cultural evolution, similar to genetic models, can be used to
explain the formation and stability of local dialects. Morphological,
genetic and cultural evolution can be compared to explain this species'
population structure. We recorded songs from individuals of the two subspecies
breeding in two different localities in northern Italy. The songs were
translated into sonograms and these were compared over a range of variables.
A catalogue of syllable types was built grouping the syllables according
to qualitative sonogram similarity. The songs of the two subspecies were
significantly different in bout length and average number of repeated
sillables. We built a syllable sequence distance matrix, using the catalogue
to count the number of shared syllable types, and performed cluster analysis,
but this did not to separate the two populations. We intend to spread
the analysis to other populations in Europe, characterize songs with more
detail, use quantitative methods to create the syllable type catalogue
and refine the syllable sequence analysis in order to build a cultural
evolution model.
The measurement of hierarchy
of the Canary (Serinus canaria) in the laboratory.
L. Luisanti Fitri, I. Béme, and M.Kreutzer
Laboratoire de Psychophysiologie et d'Ethologie,
Universite de Paris X, CNRS URA 2214,
200 Avenue de la Republique
92001 Nanterre Cedex, France
Email: 101331.3542@CompuServe.COM
Recently, it is demonstrated
that female canaries (Serinus canaria) elicit high levels of sexual
display to a special song phrase of a male fullsong. This song phrase
is called as "phrase A". However, this special song phrase is
not commonly existed in the repertoires of male canaries. This preferential
response of female canary to song "phrase A" might be considered
as one of the cue to be indicative of male quality. We made a test to
find an adeguate method of measuring hierarchy within a mixture flock
of ten individually marked males. Among these flock members only five
males have been known to have this song "phrase A" within their
repertoires. Other phenotypic that correlates to male quality such as
body weight, wing length and tarus length were also examined in the test.
The role of hierarchy was assessed by dyadic interation among flock members
in gaining access to resources provided inside the aviary. These resources
were food and bathtub box which were established at different high level.
We found that interaction among flockmates were manifest differently at
the feeder and the bathtub. Phenotypic appearances tended to have positive
correlations with the higher ranking birds at the feeder. More information
is needed to get the evidence that song "phrase A" in relation
to male quality may explain the formation of hierarchy in the canary.
Methodological considerations
on the acoustic signal analysis for two species of bats (Chiroptera
Vespertilionidae).
C. Zmarich1, E. Vernier2, F. Ferrero1
1 - Centro di Studio per
le Ricerche di Fonetica (CNR), via Anghinoni 10, 35121 Padova, Italia.
Email: Zmarich@csrf00.csrf.pd.cnr.it
2 - Dipartimento di Biologia dell'Universit di Padova, Padova (freelance)
Private office: via delle Palme 20/1, 35137 Padova, Italia
Ultrasonic emissions of bats
(Mammalis Chiroptera) consist of either social calls or
echolocation pulses. As to the latter, every bat species exploits peculiar
morphological features in the time and frequency domain, thereby making
them distinguishable by their unique echolocation pattern.
In this study, the echolocation pulses of two species of vespertilionid
bats have been recorded twice, first in laboratory and then in a natural
environment. The signals of adult specimens of Pipistrellus kuhlii
and Hypsugo savii are analysed and described. These species, which
are quite common in Italy, are externally similar and have antropic habits,
covering a very much similar ecological role. Their distinction is normally
based on areal spreading, physical size and morphology, and acoustic classification
criteria. The latter criterion is often used in field recording conditions
after heterodyning conversion has made the ultrasonic pulses audible to
the human ear.
The ultrasonic sounds were checked and detected with a Pettersson Ultrasound
Detector D-100 connected to a Schlumemberger magnetic recorder
Euromag 1. The recording rate was set to 38 cm/s. As for the laboratory
recording conditions, the specimens were recorded while flying inside
a 7x4x3 m room. A wide band microphone was set at 1.5 metres from the
floor near the central point of the longest wall. As for the field conditions,
specimens flying under or near street lamps (P. kuhlii) or over
little private gardens in complete darkness/poor light (H. savii)
were recorded.
In order to apply DSP analysis to the recorded signals, the magnetic
tape was played at 4.75 cm/s, making exploitation of the nominal 8 kHz
spectrographic standard range possible. In this way duration is extended
and frequency is lowered by the same 8-fold factor (the virtual interval
of 1 kHz thus corresponding to a real interval of 8 kHz). Spectrographic
analysis was performed with the DSP Sonagraph 5500 and CSL 4300
software by KayElemetrics Corp. Measurements for time and frequency
were taken through power spectra obtained by positioning the cursor on
the waveform at the initial, central and final part of each single signal.
Measurements of emission rates were taken simply by counting the occurrences
of the homogeneous signal units per second.
Some methodological suggestions are made regarding the best way to perform
spectrographic analysis on signals that differ for general shape (quasi-constant
frequency vs downward frequency modulation) and duration (short
vs long). A general difference between the lab and field conditions is
the relative greatest length of the signals in the latter. Based on measurement
values, it is possible to compare the two species only for the lab recordings,
because the signals recorded in the field are different for the different
species (QCF for H.savii and DFM for P.kuhlii). The DFM
signals of the two species both begin at 70 kHz but end at 45 kHz for
H. savii and 35 kHz for P.kuhlii. Furthermore, the signals
of P.kuhlii have greater amplitude, more steep slope and occur
in more rapid succession than those of P. savii.
Acoustic communication
and related behaviour of captive otters (Lutra lutra).
Claudio Gnoli, Claudio Prigioni, Paola Polotti
Dipartimento di Biologia Animale, Università di Pavia, Piazza Botta 9
27100 Pavia, Italy. Email: ctgnoli@imicilea.cilea.it
A male, a female, two juveniles and two cubs of European otter (Lutra
lutra) were filmed in a large enclosure during a period of 8 months.
For each episode of acoustic communication, data were collected on uttered
sounds, involved individuals, and their distance, postures, and behaviour
before, during, and after vocalizing. Eight different sounds were considered,
according to the inventory referred by Rogoschik (Wiss. Beitr. Univ. Halle,
37(1989): 213-221). Associations between the recorded parameters were
evaluated by an association index.
Male and female vocalized frequently towards the cubs and human beings,
and cubs towards the female. Senders and addressees resulted inequally
distributed for the different sounds. Vocalizations occurred preferentially
on land and along the banks. Most frequent behavioural contexts were parental
contacts (between the female and the cubs), contacts with human beings
and playing activity; on the other hand, vocalizations rarely occurred
while fishing, moving, feeding and marking.
Hiss and snort were uttered when an animal approached the addressee, from
a distance of a few meters; they were often accompanied with a typical
arcuated head movement. Moan was a threat sound, uttered while keeping
the body motionless and fixing its eyes on the addressee. Chuckle, chuckle-chitter,
chitter and squeal were mostly uttered at very short distances; although
they all show a similar "staccato" acoustic structure, only
the chuckle was uttered in social contexts, while the other ones were
associated with increasing aggressive excitement. Whistle was uttered
usually in very long sequences, at long distances; its main function seems
to be keeping an acoustic contact between individuals, in particular cubs
and their mother; however, sometimes it was uttered by juveniles together
with chitter and other agonistic sounds. This shows that the communicative
system of the species is quite complex.
Physical and functional
features of vocalization in youngs of Macaca nemestrina.
A preliminary study.
Rigamonti, M. M.1, Prato Previde, E.2, Poli, M.D.2
1 - Centro di Primatologia HSR,
via Olgettina 60, 20132 Milano, Italia. Email marcor@gea.hsr.it
2 - Istituto di Psicologia della Facolt Medica, Universit
degli Studi di Milano, Via T. Pini 1, 20134 Milano, Italia
The period immediately following
birth appears to be particularly well suited to study the developmental
similarities in vocal communication between man and other primates. Vocalisations
performed by non-human primates during their first year of life are therefore
particularly important in a comparative and evolutionary perspective,
as they allow interesting comparisons with studies on human linguistic
development. However this topic has received little attention.
We studied the functional relationships, in a social colony of pig-tailed
macaques (Macaca nemestrina), between the maternal response to
the search of physical contact by the young and the physical structure
of the vocalisations produced by the latter. The research was performed
on three mother-young dyads, audio-recording the vocalisations produced
by the young and by the adults and video-recording mother-young interactions.
Our results allow a description of some of the physical characteristics
of the vocalisations produced by the young during spontaneous interactions
with their mothers; furthermore they suggest the existence of different
structural or syntactical categories and suggest a relationship between
maternal behavior and vocalisation patterns.
Preliminary analysis of
wolf vocalizations recorded in the wild in Italy.
Lorenza Mauri, Marco Apollonio, Ettore Centofanti
Dipartimento di Scienze del Comportamento Animale e dell'Uomo
Via Volta 6, 56126 Pisa, Italy. Email: marcoapo@discau.unipi.it
During censuses of wolves,
performed with the wolf-howling tecnique, in the Foreste Casentinesi National
Park, we recorded answers of wolf packs and isolated individuals.
Most difficulties were caused by the distance between wolves and the recording
equipe. The aim of this preliminar analysis was to verify if it was possible,
in the wild, to distinguish by mean of sonagraph analysis:
a) adults from pups; b) the number of individuals of each pack; c) different
adult individuals from each others.
A first distinction is possible thanks to the different frequency range
of adults and pups vocalisations. The substantial overlapping of different
vocalisations makes the second aim difficult, but it is possible to determine
a minimum number of individuals. The third aim is difficult to reach because
only few vocalisations of each individual can be collected.
Ultrasound and mating behaviour
in the field voles, Microtus agrestis.
Marie-juliette Mandelli, G.D.Sales
Life Sciences Dept., King's
college London, UK.
Email: marie-juliette.Mandelli@kcl.ac.uk
Field voles are common in Britain and across Europe where they may show
regular fluctuations in population every 3-4 years. In some countries
they are pests of agriculture and particularly of forestry. These voles
are induced ovulators and while their reproductive physiology is fairly
well understood, little is known of their reproductive behaviour and especially
of their acoustic communication. The present study has shown that in heterosexual
encounters adult voles emit ultrasonic calls during a range of behaviours
as it had been found in several other rodents. For example, male mice
of different strains are known to emit 70 kHz - ultrasonic vocalizations
as part of their courtship behaviour and rats, emit 50 kHz pulses.
In Microtus agrestis, the nature of the calls varies particularly
in the amount of frequency modulations. The frequency ranges from 20 kHz
to 80 kHz with an average at 35-40 kHz, the male seems to be the main
emitter.
In heterosexual encounters between sexually naïve animals both sexes call,
but calling appears to be modified by sexual and parental experience,
as sexually experienced males emit longer and wider calls than sexually
naïve males, and sexually experienced females do not emit any ultrasonic
pulses when presented with an anaesthetised male (also sexually experienced)
as sexually naïve female do. The environment in which the animals meet
also effects ultrasound emission: the calls emitted by pairs in the male's
home cage were longer and of broader-bandwidth than those emitted in the
home cage of the female. The effect, on the emission of ultrasonic pulses,
of sexual and parental experience as well as the effect of different environments
will be illustrated. The relationship between calls and the different
types of behaviour and the effect of these calls on the recipients are
currently being investigated.
Analysis of ultrasound
using AVISOFT-sonagraph software.
Raimund Specht
Haupstr. 52, D-13158 Berlin,
Germany
Email: Raimund.Specht@t-online.de
There are two methods of ultrasound
acquisition and analysis with PC's:
The first and most straightforward solution is a special data acquisition
board with a sampling frequency high enough to capture the entire bandwidth
of the signals to be analysed. This requires to take the computer into
the field if you have to do field research. The best choice would be a
PCMCIA data acquisition card for portable notebook PC's. Unfortunately
the devices available on the market still have limited sampling frequencies
of approximately 100 kHz. This allows a usable bandwidth of less than
50kHz which is not sufficient for all kinds of ultrasound. The data streams
generated by these data acquisition boards can be stored on hard-disk
and can then be read by the Avisoft-SONAGRAPH software using one of its
user-defined import formats.
The alternative method is the usage of a digital time-expansion bat-detector
to transform the ultrasound into low frequency sound which can be processed
by conventional audio equipment. These transformed sounds can be stored
on standard tape recorders and can be transferred into the computer using
a common sound-card. In this case the transformed ultrasound is treated
like any other audio signal. In order to get the original scaling of waveforms,
spectra and sonagram displays the time-expansion factor used on the bat-detector
can be specified in the Avisoft-SONAGRAPH software.
Conventional bat-detectors using heterodyne or frequency division technology
are not suited for spectral analysis on a computer. These devices could
only be used to get an idea of the time structure of the signals.
Ultrasound acquisition
and analysis. Comparison of current methods.
Pavan G.1,2, Manghi M.1
1 - Centro Interdisciplinare
di Bioacustica e Ricerche Ambientali, Università degli Studi di Pavia
Via Taramelli 24, 27100 Pavia, Italia. Email: webcib@ipv512.unipv.it
2 - Dipartimento di Urbanistica, Istituto Universitario di Architettura
di Venezia, Italia
Instrumentation recorders
designed to record ultrasounds are very expensive and not well suited
for field use; thus, cheaper devices to detect and possibly record ultrasound
were developed for field research, mainly to study echolocation in bats.
These are called bat detectors. Basically they employ three methods for
making ultrasounds more manageable: heterodyne conversion, frequency count-down,
and time-expansion. Only the last method allow the complete recording
of all the features of the ultrasonic signals. It is based on the digital
recording with a high enough sampling rate (typically ranging among 300
and 400 ksamples/sec) and on the subsequent playback at a reduced sample
rate to fall ultrasonic frequencies within the range of conventional audio
recorders.
This procedure doesn't allow long recordings. Better suited to long recordings
is the digital acquisition on a PC and several acquisition boards on the
market allow for this.
We developed a PC based Digital Signal Processing Workstation (DSPW),
based on a Microstar DAP 2400E/6 acquisition board, to allow recording
and playback of acoustic signals up to 150 kHz with a resolution of 12
bits (72 dB dynamic range). The actually available Pentium CPUs allow,
together with highly optimized custom made software, to analyze and display
spectrograms in real-time up to 150 kHz while performing hard-disk recording
and other data analysis and logging tasks. A sharp anti-aliasing filter
is required to prevent aliasing.
When sampling at 312.5 ks/sec a 2 GB hard disk allows the continuous recording
of up to 56 minutes.
This instrumentation is very useful in laboratory experiments to monitor
the ultrasonic activities of the research subjects and to optimize the
instrumental setup (minimization of noise sources, microphone placement).
Also it allows to immediately evaluate the results of an experiment instead
of waiting for later analyses on the recordings.
Special analysis procedures allow to log data in real-time (onset, offset,
freq. tracking) and to produce reports about the monitored signals.
Real-time spectrographic
analysis with Sound Blaster sound boards.
Gianni Pavan1,3, Ethan Brodsky2
1 - Centro Interdisciplinare
di Bioacustica e Ricerche Ambientali, Università degli Studi di Pavia
Via Taramelli 24, 27100 Pavia, Italia. Email: webcib@ipv512.unipv.it
2 - 4010 Cherokee Dr., Madison, WI 53711, USA
3 - Dipartimento di Urbanistica, Istituto Universitario di Architettura
di Venezia, Italia
Spectrographic display of
animal sounds has been widely used since the first analogical analysis
instruments were developed for military acoustic research. However, until
recently, the high cost of the specialized hardware necessary for this
type of analysis made it inaccessible to most researchers. The recent
development of digital signal processing techniques and high-speed hardware
at relatively low-cost has made the real-time visualization of acoustic
signals an every-day invaluable tool for bioacoustic research and education.
A new version of the DSPW software already described in previous reports
has now been developed to use CreativeTM Sound Blaster and compatible boards. The software strictly
requires 16 bit sound boards (Sound Blaster 16, Sound Blaster 32 and true
compatibles, including those based on the Vibra 16 chipset); it is DOS
based and uses a high DMA channel (4-7) to perform continuous gap-free
transfer of samples from the board to the computer memory. Since several
notebooks now incorporate Sound Blaster compatible sound devices, this
software opens new perspectives in field applications.
The software is a powerful display and analysis tools. Depending on the
CPU speed (a Pentium is recommended), overlap and zero-padding can be
performed in real-time to get smooth time-frequencies plots up to 44.1
ks/sec. Both spectrogram and cepstrogram can be computed in real-time.
Three basic real-time display modes are available: horizontal display
with envelope (wrap around or scrolling display), four strips scrolling
display, vertical scrolling display.
Even if cheap sound boards seem to be adequate for music and games, some
problems are still to be solved when analyzing sounds: signal to noise
ratio, bit resolution, frequency response, anti-aliasing filters, available
sampling frequencies (most boards allow sampling rates ranging from 5
ks/s to 44.1 ks/s) and sampling frequency accuracy change depending on
the sound board model. Thus, a great care must be used when using digitizing
devices which are not designed for great accuracy. Before to start using
a particular sound device, a series of tests must be made. For this purpose,
a collection of freeware utilities have been developed by Philip van Baren
to check the real performances of Sound Blaster boards.
A freeware version of the real-time software will be soon available on
the net.
Web references
G.Pavan, http://www.unipv.it/webcib/
E.Brodsky, http://www.pobox.com/~ebrodsky/
P.vanBaren, http://bul.eecs.umich.edu/~phillipv/signal/
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