BIOACOUSTICSTable of Contents: Volume 9
BIOACOUSTICS
C. Doutrelant, T. Aubin, S. Hitier & M.M. Lambrechts (1998). Two distinct song populations of Blue Tit Parus caeruleus in the French Mediterranean. Bioacoustics 9(1): 1-16
Abstract
Blue tits, as many other species, show much geographic variation in their songs. In blue tits, songs that include a trill (series of rapidly repeated notes) are widespread on the European mainland, but have not been reported in North Africa or the Canary Islands. We studied song structure of two blue tit populations from the French Mediterranean that are exposed to large differences in local selection pressures (food, vegetation, social factors). Songs from populations on the European mainland and the island of Corsica differed much in syntax, tempo, frequency, and the incidence of trills. The observed population differences could potentially be caused by a combination of different factors, including biotic and abiotic habitat characteristics, body size, and cultural drift. We suggest that songs without trill are acoustically adapted for transmission in habitats where the local breeding density of great tits is low. In addition, we suggest that songs with trill may reject a character shift to minimise territorial interactions with great tits.
Keywords: blue tit, Parus caeruleus, dialect, regiolect, interspecific competition, song.
N. Mathevon (1998). Degraded temporal sound features as a function of distance and potential as cues for ranging in birds. Bioacoustics 9(1): 17-33
Abstract
An acoustic signal is altered by various processes during long-range propagation. Birds may use degraded sound features to assess the distance of the emitter. To know which temporal sound features are susceptible to be used by birds for ranging, we performed a study using natural and synthetic acoustic signals which had different temporal sound degraded characteristics, i.e amplitude and frequency modulations and sound-silence alternations.
Our data show that the degradation of some temporal features may give ranging information, especially in a forest environment. Indeed, in an open field, the assessment of an emitter's distance using sound temporal features may be rather difficult since there is no modification of sound/silence alternation, frequency-modulated notes are preserved, and fluctuations of amplitude are at random, except for high-pitched sounds. In contrast, forest birds may rely on different parameters for ranging, since in this environment duration of notes, degradation of frequency modulation as well as degradation of amplitude modulation of high-pitched notes are linked with propagation distance.
Keywords: sound propagation, acoustic communication, sound degradation, temporal features, birds, ranging
R. Jehle & A. Arak (1998). Graded call variation in the Asian cricket frog Rana nicobariensis. Bioacoustics 9(1): 35-48
Abstract
We describe the vocal repertoire of the Asian cricket frog Rana nicobariensis for the first time. Three structurally-distinct call types exist: advertisement calls, aggressive calls and encounter calls. Compound calls consisting of both advertisement and aggressive elements were also recorded. A remarkable feature of communication in this species is the highly variable advertisement call which shows a 20-fold variation in duration, comprising 1-25 notes. In natural choruses, the duration of the advertisement call is inversely related to the distance between a focal male and its closest calling neighbour. In playback experiments, males clearly responded to stimuli containing different numbers of notes by adjusting the number of notes emitted. However, they did not match the stimulus precisely, and were inhibited from calling by a stimulus consisting of a continuous train of notes. Different proportions of each call type were recorded during playbacks at different distances; aggressive and encounter calls were increasingly emitted at closer distances. Our results suggest that a graded communication system has evolved in Rana nicobariensis, in which the best call for a male to use at any moment depends on the type of calls being emitted by other males in the chorus.
Keywords: Rana nicobariensis, Malaysia, acoustic communication, graded call variation
T. Dabelsteen, P.K. McGregor, H.M. Lampe, N. Langmore & J. Holland (1998). Quiet song in song birds: an overlooked phenomenon. Bioacoustics 9(2): 89-105
Abstract
The theory of communication networks offers functional arguments for the evolution of unobtrusive signals in birds. The vulnerability of interacting conspecifics to predation and to eavesdropping by neighbours during both territorial disputes and courtship would select for short range signals such as the quiet songs of birds. In addition to suggesting contexts in which quiet songs should be used, we use our knowledge of the physics of sound transmission to make predictions about the physical structure of such songs relative to the well studied full songs. We present support for these predictions in six species where quiet singing has been observed.
Keywords: bird song, quiet singing, communication networks, sound transmission.
S. Bertram & L. Johnson (1998). An electronic technique for monitoring the temporal aspects of acoustic signals of captive organisms. Bioacoustics 9(2): 107-118
Abstract
We introduce an inexpensive electronic technique for monitoring the temporal aspects of any captive animal's acoustic signals. The electronic apparatus, attached to a data acquisition unit and personal computer, compares microphone output to a pre-set level and stores calling/non-calling data to disk. Total time calling and temporal signaling patterns of up to 256 individuals can be monitored for indefinite lengths of time. Sampling rate is adjustable, with a maximum rate of 6 samples/microphone/second. The capabilities of the system are illustrated with the field cricket Gryllus integer. Temporal aspects of acoustic signaling are discussed in terms of monitoring time scale and recognition of individual variation, energetics research, and hypothesis testing of the costs and benefit,: associated with mating success and predation.
Keywords: temporal, calling, patterns, electronic, technique
P.-C. Schon, B. Puppe & G. Manteuffel (1998). A sound analysis system based on LabVIEW applied to the analysis of suckling grunts of domestic pigs Sus scrofa. Bioacoustics 9(2): 119-133
Abstract
The paper gives an overview of the capacities of the software solutions for a sound analysis system based on the program development environment LabVIEW and shows some applications of the system by using suckling grunts of domestic pigs Sus scrofa as an example.
LabVIEW represents a versatile tool for the development of sound analysis software including sound processing and sound statistics. Particularly, the increasing need for flexible numerical processing of different acoustic parameters can be considered. The graphical object -oriented language allows programming without special experience because it uses terminology, icons and theories familiar to scientists and engineers. LabVIEW is available for Macintosh, Sun, HP-UX, Windows 95, Windows NT, Windows 3.1., and can also be used as a teaching tool to gain technical knowledge of signal analysis and signal processing.
Paralleled by behavioural observations, the bioacoustical studies of animals at various levels, including the incorporation of techniques that are used in animal communication, human speech recognition or in technical acoustics, are able to reveal the specific meaning of vocalisations. Based on the example of the analysis of suckling grunts of domestic pigs the impact of an application of the system developed in our group is demonstrated.Keywords: vocalisations, sound analysis, bioacoustics, LabVIEW, domestic pigs
L. May (1998). Individually distinctive corncrake Crex crex calls: a further study. Bioacoustics 9(2): 135-148
Abstract
Male cornflakes Crex crex produce repetitive calls the elements of which are composed of individual pulses. The inter-pulse intervals were measured for elements of calls from ten birds recorded on one to three nights. The abilities of discriminant analysis and two artificial neural nets to correctly attribute calls to birds across nights, using sets of vectors of inter-pulse intervals, were compared. Discriminant analysis correctly attributed all calls to the correct individual without error. One of the two neural nets incorrectly attributed less than 1% of calls. Using coded data the second neural net incorrectly attributed less than 6% of calls overall but the individual error rate varied between zero and more than 50%.
Keywords: corncrake, multivariate, discriminant analysis, neural network, classifier, threshold
I. Wilden, H. Herzel, G. Peters & G. Tembrock (1998). Subharmonics, biphonation and deterministic chaos in mammal vocalizations. Bioacoustics 9(3): 171-196
Abstract
To establish a framework for discussing mammalian vocalizations, relevant terminology and concepts from the theory of nonlinear dynamics are introduced. It is suggested that a variety of nonlinear phenomena including subharmonics, biphonation, and deterministic chaos are normally occurring phonatory events. The whole spectrum of these phenomena can be found in the repertoire of the African wild dog Lycaon pictus. In addition, examples of nonlinear phenomena in a wide range of other mammalian taxa will be presented. Moreover, some artifacts in sound spectrographic analysis are listed which may be misinterpreted as nonlinear phenomena.
Within the framework of nonlinear dynamics, a consistent terminology is proposed and our observations are related to laryngeal sound production mechanisms. Finally, some hypotheses concerning the communicative potential of the described phenomena are discussed.
Keywords: Mammal vocalization, nonlinear dynamics, subharmonics, biphonation, chaos
L.S. Durbin (1998). Individuality in the whistle call of the Asiatic Wild Dog Cuon alpinus. Bioacoustics 9(3): 197-206
Abstract
The Asiatic wild dog or dhole Cuon alpinus is a threatened social canid that uses a repetitive whistle call to maintain group contact in dense habitats. Spectrographic analysis revealed significant differences between the whistles of captive dholes, allowing callers to be reliably identified. The most important discriminatory characteristics were the period from the start of one syllable to the next, the fundamental frequency, and the maximum frequency. The individual distinctiveness of the whistle is discussed in terms of its functional significance and possible survey applications.
Keywords: dhole, Cuon alpinus, canid, vocalisations, individuality
A.P. Norman, L. Teagle & G. Jones (1998). A method for the synchronisation and control of ultrasound recording and sterophotogrammetry in the reconstruction of animal flight. Bioacoustics 9(3): 207-212
Abstract
We describe equipment that controls the operation of flash guns for use in stereophotogrammetry and enables recording or the playback of bat calls to be synchronized with the photographic data. This equipment can readily be built using standard components and is suitable for use in the field.
Keywords: stereophotogrammetry, ultrasound recording, flight, bat, moth
S.S. Boatright-Horowitz, C.A. Cheney and A.M. Simmons (1999). Atmospheric and underwater propagation of bullfrog vocalisations. Bioacoustics 9(4): 257-280
Abstract
Male bullfrogs vocalize while partially submerged in shallow freshwater ponds. This imposes two potential propagation pathways, atmospheric and underwater, on transmission of their communication sounds. Propagation of pure tones, amplitude modulated (AM) broadband noise and natural calls was measured in air and underwater at three bullfrog breeding sites. In air, propagation losses were consistent with spherical spreading. No excess attenuation was observed for any tone frequency at any site. Both temporal envelope modulations and spectral cues are available to conspecific receivers at biologically realistic distances. The bullfrog's advertisement call is thus well adapted for transmission in air at the air/water interface. Underwater signal propagation differed at the three sites, consistent with substrate effects. Tone propagation showed the high-pass frequency window characteristic of shallow water. Broadband signals underwent propagation losses greater than expected by cylindrical spreading. Modulations of the envelope of natural calls remained discernible at distances where frequency-dependent propagation losses distorted the shape of the spectrum. Measurements of the propagation of the advertisement call emitted by a chorusing frog at the air/water interface confirm that periodicity cues embedded in the envelope are available to receivers both in air and underwater. High frequency cues available underwater overlap the maximal hearing sensitivity of larval conspecifics (tadpoles).
Keywords: Sound transmission, amphibian, propagation, vocalization, atmospheric, shallow water, communication
P. Hansen (1999). Long term stability of song elements in the yellowhammer Emberiza citrinella. Bioacoustics 9(4): 281-295
Abstract
The songs of 175 yellowhammer Emberiza citrinella males were recorded in an area of 10 km2 in 1977-1981, 1983 and 1996. Each male had a repertoire of 1-3 song types (mean: 2.1), being categorized mainly by the first part of the song, which is a repetition of a sound pattern (the a-element). Comparisons of population repertoires of a-elements between years showed that a-elements had an annual survival rate of about 95%.
In a computer simulation all 373 a-elements from the study years (the summed male repertoires) were pooled (distributed among 80 a-element types). From this pool samples of a-elements were drawn, corresponding to the sample size of each study year, and the number of types per year and shared types between years were calculated. Both measures fitted well to the actual findings in the population.
Thus the recorded songs might have been drawn from a stable song type population, suggesting that yellowhammer song elements are transmitted culturally through a considerable number of generations.
The mechanisms which might be responsible for the slow degree of cultural evolution in yellowhammer songs are discussed.
Keywords: yellowhammer, Emberiza citrinella, song element, cultural evolution, computer simulation.
I.M. King (1999). Species-specific sounds in water bugs of the genus Micronecta. Part I, Sound Analysis. Bioacoustics 9(4): 297-323
Abstract
This is the first reported study of corixid water bugs examining whether all species of a genus in one locality can be distinguished by their sounds. More extensive analysis than has been reported for any corixids revealed that, although some species are difficult to distinguish morphologically, inter-species sound differences are very clear.
The sounds of all nine species of Micronecta in the study area near Melbourne, Australia were recorded. Male sounds were recorded in the laboratory, over a minimum water temperature range of 15 to 25°C. Females do not produce sounds. Signals consisted of groups of pulse-trains, except for one species with signals of usually one pulse-train. Signals were species-specific; pulse-train rate alone was sufficient to distinguish between species. There were also species differences in other signal parameters. Males also produced clicks (single pulse-trains) and low-amplitude sounds; there were some species differences in the latter. Similar signals occurred between only one pair of species, which were from different habitats (ponds and rivers). Pulse periods and pulse-train periods were negatively correlated with temperature, with curves of best fit being quadratic. Five species were also recorded in ponds; the sounds and effect of temperature were compared with laboratory recordings.
Keywords: Acoustic communication, species-specific sounds, Micronecta, water bugs, corixids.
H. C. Bennet-Clark (1999). Which Qs to choose: questions of quality in Bioacoustics? Bioacoustics 9(4): 351-359
Abstract
Two Q factors are in common use in bioacoustics: Q, the Quality Factor and Q10dB. The usage, definitions and separate application of these two terms can be traced back for more than 30 years. The two terms provide different measurements of the sharpness of tuning of e.g. acoustic systems. The two terms have been used in separate contexts and they measure different things. In view of the confusion that arises from the shared use of the letter Q, it is important that whichever Q is used is defined clearly in all publications.
Keywords: Q; Quality factor; sharpness of tuning; Q10dB; resonance.