Bioacoustics

Published by Taylor & Francis
Print ISSN: 0952-4622
Publications
Previous research on inter-individual variation in the calls of corvids has largely been restricted to single call types, such as alarm or contact calls, and has rarely considered the effects of age on call structure. This study explores structural variation in a contextually diverse set of "caw" calls of the American crow (Corvus brachyrhynchos), including alarm, foraging recruitment and territorial calls, and searches for structural features that may be associated with behavioural context and caller sex, age, and identity. Automated pitch detection algorithms are used to generate 23 pitch-related and spectral parameters for a collection of caws from 18 wild, marked crows. Using principal component analysis and mixed models, we identify independent axes of acoustic variation associated with behavioural context and with caller sex, respectively. We also have moderate success predicting caller sex and identity from call structure. However, we do not find significant acoustic variation with respect to caller age.
 
Examined a new acoustic signal in Drosophila simulans (SI) and D. melanogaster (ME). It is a rejection signal (RS) produced by adult males and young males and females in response to the courting behavior of mature males who emit pulse songs (i.e., love song; [LS]). The RSs produced by adult males or by young animals do not differ significantly. They are emitted by neither virgin nor fecundated adult ME females but a few times by virgin adult SI females. The RS (like the LS) is a multipulse signal but intervals between pulses are about twice those of LS, around 90 ms for SI and 80 ms for ME. They are very irregular, as is the distribution of energy along the bandwidth mainly between 300 and 800 Hz for SI and 200 and 600 Hz for ME. The RS seems to be linked to the flicking behavior produced by both wings, while the LS always corresponds to the so-called wing vibration. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Measured sound propagation in a shallow sloping-bottomed freshwater pond. The frequency responses of the pond had a highpass characteristic with a sharp cut-off frequency. Cut-off frequency of the response was inversely related to the depth of water at the shallowest transducer. The relationship between cut-off frequency and depth was significantly different from that expected for propagation in a channel with either a rigid or pressure release bottom. Thus, the physical constraints of this shallow-water environment on acoustic communication by aquatic animals are much greater than those measured in terrestrial environments. These constraints are discussed relative to selection for behavioral adaptations of acoustically signaling aquatic animals and are compared to similar adaptations found in terrestrial systems. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
When studying the acoustic signals of animals, it is often necessary to obtain the precise time structure of the frequency. It is also useful to extract the envelope of a signal or to modify a signal to obtain its frequency modulated part. This can be achieved digitally using the analytic signal concept.We deal here with the method. Definition and computation are described, its application is discussed and the performances are compared to those of sonagraph and zero- crossing methods. This paper presents a method enabling precise AM and FM analysis of different animal vocalisations. The method has also been used for the purpose of synthesis by extracting the frequency modulated part of a signal. It is found to be a powerful means of modifying some parameters of a natural signal without altering other features.
 
Developed and field-tested a passive acoustic detector that collects data on sound production by sonic fish. The detector was deployed to measure the timing of sound production by male damselfish. Sound production rates were higher during the reproductive season (April) than during the non-reproductive season (October). The highest rates of sound production occurred on the day before and day of egg-laying. Sound production rates decreased during brood care, and increased again after hatching. The correlation of sound-production rate with the spawning cycle provided a reliable acoustic signal that was monitored by the detector. This new technology provides a capability for obtaining detailed measurements of reproductive activity over long time periods. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Detailed descriptions of the acoustic signals of European cicadas are available only for a few species. In this paper the acoustic signals and biomechanics of the timbals in nine species of cicadas from Portugal have been examined. Those species are Cicada barbara lusitanica (Boulard, 1982), C. orni (Linnaeus, 1758), Tettigetta argentata (Olivier, 1790), T. atra (Gomez-Menor, 1957), T. estrellae (Boulard, 1982), T. josei (Boulard, 1982), Tibicina quadrisignata (Hagen, 1855), Tympanistalna gastrica (Stal, 1854), and one unidentified species of Tettigetta. A qualitative and quantitative description of the sound is given in the time domain and the frequency domain. An acoustic male-to-male interaction signal that ceases the courtship was identified in C. barbara lusitanica. Some evolutionary aspects related to the biomechanics of the timbals and to the sounds produced are discussed.
 
Two sets of experiments studied song production and recognition in 3 species of grasshoppers: Chorthippus dorsatus (CDO), Ch. dichrous (CDI), and Ch. loratus (CLO). The songs of males contain pulsed syllables produced during synchronous movements of the hindlegs (Part A) and ongoing noise produced during alternating movements of the hindlegs (Part B). The ability of females to discriminate between songs by the males was examined. Results reveal that Part A predominated in songs of CLO and Part B in CDI and in CDO both parts contributed equally, female stridulation of all the species was similar to male stridulation, females preferred the conspecific signals over heterospecific ones, and long copulations were observed between CLO females and CDO males. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
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. Recordings were made over 12 days of dholes kept in 2 adjacent enclosures at a wild animal park. Spectrographic analysis of digitized recordings 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. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Compared several features of the chatter call of 2 races of black-billed magpies, the nominate, European race Pica pica pica and the North American race P. p. hudsonia and the yellow-billed magpie P. nuttalli. The chatter calls of the North American species were much more similar to each other than either was to the European magpie. This information, together with the recently determined similarities in the behavior and social organization of the 2 North American species, suggests that the phylogenetic affinities of these species are closer than is implied by their taxonomic status. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Outlines the special problems encountered in the analysis of nonperiodic frequency modulation signals by an instrument such as the sound spectrograph, which is constrained by the uncertainty principle. Thus, to increase accuracy of measurement in one dimension, accuracy of measurement in the other dimension must be sacrificed. Although this trade-off is unavoidable, inherent in the measurement of frequency there is an intermediate, optimal setting of spectrographic bandwidth, equal to the square root of the average rate of change of the measured signal. This optimal bandwidth permits the most accurate measurement of the instantaneous frequency. Investigators analyzing the microstructure of animal vocal signals therefore should choose their analyzer bandwidths to match the signals under study. Examples are presented with bird calls and songs. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Seasonal changes of parameters of full song were studied in a free-living population of chaffinches during 1 entire reproductive period. Approximately 7,000 strophes sung by 14 male chaffinches were recorded and analyzed by sonography and an oscillographic method. While the general pattern of song strophes (i.e., characteristics of elements, number and arrangement of phrases, and final flourishes) remained constant throughout the reproductive period, full song varied with respect to the repetition rate of the strophes, number of strophe types used, intensity of singing, duration of strophes, and percentage of incomplete strophes sung. These changes are discussed as results of learning processes, social interactions in the population, and endogenous mechanisms activating memorized information. (German abstract) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Recorded echolocation and ultrasonic social signals of a gleaning bat. Ss used nearly linearly modulated echolocation signals of high frequency with a weak 2nd harmonic. The orientational signals from patrolling bats were about 2.4 msec in duration and occurred at a repetition rate of about 18 Hz. The signals used by bats as they approached the screen were of shorter duration and occurred at higher rates. Social signals were characterized by their longer durations, lower frequencies, and curvilinear sweeps. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Nuttall's white-crowned sparrow ( Zonotrichia leucophrys nuttalli) and the Puget Sound white-crowned sparrow ( Z. i. pugetensis) intergrade through a zone of hybridization in northern California. The songs of the 2 subspecies differ in the sequence of syllable types and in the phonology of the complex syllables. A playback experiment was conducted with males of both subspecies in the field and with females of both subspecies in the laboratory to determine their response to the 2 subspecies songs. Males of both subspecies were more responsive to their own subspecies song than to that of the other subspecies. Females of both subspecies gave more sexual displays when played a song of their own subspecies than when played that of the other subspecies. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Demonstrated that incomplete song strophes in 16 free-living territorial Chaffinch males can be induced by different experimental as well as natural stimulus situations. They included replay of species-specific song, approaching of human beings, and aggressive encounters with conspecific males. While the 1st poststimulus song strophe was shortest, the following ones gradually attained their full number of elements again. The strength of this reaction differed with regard to different stimuli. Incomplete song output may be a useful device for measuring a bird's internal state. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
"Pure tones" are a distinctive acoustic feature of many birdsongs. Research suggests that such sounds result from coordinated interaction between the syrinx and a vocal filter, as demonstrated by emergence of harmonic overtones when a bird sings in helium. The present study used field playback experiments to compare responses of 30 male swamp sparrows to normal songs and those same songs recorded in helium. Responses were measured to pure tone songs that had been shifted upward in frequency to match the average spectra of those songs with added harmonics. Ss were significantly more responsive to playback of normal songs than to helium songs with added harmonics or to frequency-shifted pure tone songs. Songs with harmonics retained a high degree of salience, however. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Discusses the development and social functions of signature whistles in bottlenose dolphins. Dolphins recognize these whistles of animals with which they share a social bond. Signature whistles develop within the first few months of life and are stable for a lifetime. Vocal learning appears to play a role in their development as the signature whistles of most female dolphins and about half of male dolphins differ from those of their mothers. Some dolphin calves born in captivity develop a signature whistle that matches either man-made whistles or those of an unrelated dolphin. Dolphins retain the ability as adults to imitate the whistles of animals with which they share strong individual-specific social relationships, bonds that may change throughout their lifetime. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Explored the complexity of the advertising song in the male pied flycatcher and its variability within and between breeding seasons by qualitative and quantitative analyses of its structure. Songs were recorded from 117 males in central Norway in 1 or more of the 3 stages of the breeding season: before pairing, during nest building, and in the laying/brooding stage. When the males became mated their song changed in a number of ways. From 1 yr to the next the song of the male pied flycatchers became more versatile, the number of unique figures increased, and there was a tendency toward increasing repertoire size. New song figure types and song types appeared between years in individual males of any age. This may indicate that song learning continues into adulthood, or that subsets of early memorized songs are used in different years. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Analyzed the structure of the complex, multisyllabic warble song of the budgerigar Melopsittacus undulatus, a small flock-living parakeet. Eight male budgerigars from 3 different social groups and 1 female were recorded. 42 syllable classes were identified in the warble songs, ranging from simple clicks to multinote, frequency-modulated, musical-sounding syllables. Males shared a significantly greater percentage of their warble syllable-class repertoire with males in the same social group than with males in different groups. One male budgerigar preferentially imitated the syllables and temporal pattern of the abnormal warble of his cagemate (a male bird that had been reared in acoustic and social isolation) rather than the normal warble of other male budgerigars. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
There is a need to improve the assessment of causes and consequences of vocal behaviour. The lack of descriptions of the context of call or song production comes from the complexity of its definition. The context is composed of numerous physical and social parameters and therefore its analysis should be multi-dimensional. Classical approaches involve a relatively subjective data reduction. This is due to a pre-selection of the parameters which may be potentially involved, as the analysis becomes rapidly complicated when the number of factors increases. This paper describes a helpful method that allows a much wider range of potential parameters to be explored and displayed visually. The parameters selected for subsequent analysis are those indicated by the display as most relevant and are therefore not arbitrary. We applied this method to observations of events (external or internal to the group) or behaviours (including postures) preceding and following call production. Calls of Campbell's monkeys Cercopithecus campbelli present call types composed of several stereotyped sub-types, raising the question of whether or not such variations have a functional meaning for animals. We present three examples of the application of this method to describe in detail the context of production of a given call type, to detect specific temporal sequences of production and to discriminate between structurally close sub-types. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Classified the acoustically complex predator-elicited calls of the Florida scrub jay by dichotomous sorting. Vocalizations were tape-recorded during natural and experimental encounters between scrub jays and several types of live and mounted predators. Six continuous, independent variables of frequency and duration were measured in 539 randomly selected calls. Principal components analysis (PCA) was used to identify the variables that contributed the most variation to a given data set. Hierarchical cluster analysis was used to confirm the PCA-based approach and to explore unresolved variation in heterogeneous categories. These steps produced specific criteria to classify 12 call types and subtypes that included several inflected types that rose and fell in frequency, steep and low calls that only rose in frequency over time, and flat call types that did not change in frequency over time. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
Examined aspects of the acoustical structure of vocalizations of timber wolf pups. Audio and video recordings were obtained from birth through the 1st 6 postnatal wks, after which time the pups emerged from the den. The audio recordings were analyzed spectrographically and the vocalizations were classified according to gross spectral type, duration, presence and rate of frequency modulation, and spectral bandwidth. Joint differences in at least 2 dimensions were necessary to classify vocalizations. The most common sounds, present as early as Day 1, were harmonically structured, with fundamental frequencies that decreased with age. Other vocalizations, which were rare and resembled recognizable adult sound types, were not apparent until after the 2nd postnatal wk. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
 
The acoustic field consists of oscillating particles causing pressure fluctuations. Many aquatic organisms can detect the particle acceleration in the acoustic field and are therefore sometimes more susceptible to this component of the sound field rather than to the acoustic pressure (Kalmijn 1988). In this study, the particle acceleration generated by various boat types is measured using two hydrophones.
 
Spectrograms visualise the time-frequency content of a signal. They are commonly used to analyse animal vocalisations. Here, we analyse how far we can deduce the mechanical origin of sound generation and modulation from the spectrogram. We investigate the relationship between simple mathematical events such as transients, harmonics, amplitude- and frequency modulation and the resulting structures in spectrograms. This approach yields not only convenient statistical description, but also aids in formulating hypotheses about the underlying mathematical mechanisms. We then discuss to what extent it is possible to invert our analysis and relate structures in spectrograms back to the underlying mathematical and mechanical events using two exemplary approaches: (a) we analyse the spectrogram of a vocalisation of the Bearded Vulture and postulate hypotheses on the mathematical origin of the signal. Furthermore, we synthesise the signal using the simple mathematical principles presented earlier; (b) we use a simple mechanical model to generate sounds and relate experimentally observed mechanical events to characteristics of the spectrogram. We conclude that although knowledge of sound producing systems increases the explanatory power of a spectrogram, a spectrogram per se cannot present unambiguous evidence about the underlying mechanical origin of the sound signal.
 
Vocal complexity is an important concept for investigating the role and evolution of animal communication and sociality. However, no one definition of ‘complexity’ appears to be appropriate for all uses. Repertoire size has been used to quantify complexity in many bird and some mammalian studies, but is impractical in cases where vocalizations are highly diverse, and repertoire size is essentially non-limited at realistic sample sizes. Some researchers have used information-theoretic measures such as Shannon entropy, to describe vocal complexity, but these techniques are descriptive only, as they do not address hypotheses of the cognitive mechanisms behind vocal signal generation. In addition, it can be shown that simple measures of entropy, in particular, do not capture syntactic structure. In this work, I demonstrate the use of an alternative information-theoretic measure, the Markov entropy rate, which quantifies the diversity of transitions in a vocal sequence, and thus is capable of distinguishing sequences with syntactic structure from those generated by random, statistically independent processes. I use artificial sequences generated from different stochastic mechanisms, as well as real data from the vocalizations of the rock hyrax Procavia capensis, to show how different complexity metrics scale differently with sample size. I show that entropy rate provides a good measure of complexity for Markov processes and converges faster than repertoire size estimates, such as the Lempel–Ziv metric. The commonly used Shannon entropy performs poorly in quantifying complexity.
 
The vocal development of cranes (Gruidae) has attracted scientific interest due to a special stage, so-called voice breaking. During voice breaking, chicks produce both adult low-frequency and juvenile high-frequency vocalizations. The triggers that affect voice breaking are unknown. For the first time, we study the vocal development of the Demoiselle Crane (Anthropoides virgo). We describe the age and possible drivers of the onset of voice breaking. We analyse the calls of 21 Demoiselle Crane chicks, and compare them with the calls of six adult birds, noting the day when adult low-frequency calls are first recorded as the day when voice breaking begins. The age of voice breaking onset does not depend on hatching date, clutch order or chick body mass. Thus, there is no correlation between body growth and the onset of voice breaking for individual Demoiselle Crane chicks. However, there is a strong relationship between body mass and voice breaking among different crane species. Demoiselle Cranes stop intense body growth at the age of 2 months and start voice breaking at 70 ± 46 days. By way of comparison, Red-crowned Cranes finish the period of intense body growth at the age of 7 months and start voice breaking at 211 ± 60 days. Thus, we show that the Demoiselle Crane has a sudden vocal development, similar to other crane species, and we suggest that the end of intense body growth is the trigger for the onset of voice breaking in cranes.
 
During the last few decades, whale watching has expanded into a billion-dollar industry covering more than 87 countries worldwide. Concern has arisen that this nearly exponential growth may have negative consequences for marine mammals. Various studies have documented short-term effects of cetacean tourism. Recent studies that provide evidence for long-term detrimental effects of whale watching has led the International Whaling Commission to acknowledge that there might be direct fitness reductions associated with this industry (International Whaling Commission 2006). It is likely that at least part of the negative effects can be attributed to increased noise levels. This study sought to quantify the noise levels of two small vessels that are representative for whale-watching and research boats in order to estimate the masking impact on acoustic communication range in two delphinid species commonly approached by whale watchers and researchers.
 
Cetacean-watch tourism targets specific communities of animals that are repeatedly sought out for prolonged close-up encounters. There are concerns over the potential for detrimental consequences of this industry on targeted animals. A lack of detailed information gathered over suitable temporal scales has previously precluded impact assessments of biological relevance. However, emergent research indicates that cetacean-watch activities can cause biologically significant impacts. This was recently acknowledged by the International Whaling Commission's Scientific Committee (2006): "[t]here is new compelling evidence that the fitness of individual odontocetes repeatedly exposed to whale-watching vessel traffic can be compromised and that this can lead to population-level effects".
 
In this paper, modern time-series analysis methods are applied to the detection of possible nonlinear and chaotic features of gadfly petrel (Pterodroma sp.) sounds. Some of the recordings contain a considerable amount of noise due to wing flapping and wind. Poor signal-to-noise ratio usually impedes the chaos analysis, and thus noise-reduction methods play a significant role in the analysis. The results of two different tests are presented. First, the nonlinearity of the petrel vocalizations is tested using an information theoretic method –linear and nonlinear redundancies. Secondly, the local Lyapunov exponents are utilized as an indication of possible chaotic dynamics in the signal production system.
 
The trunk-like nose of the saiga antelope Saiga tatarica is a striking example of an exaggerated trait, assumed to having evolved as a dust filter for inhaled air. In addition, it functions to elongate the vocal tract in harem saiga males for producing low-formant calls that serve as a cue to body size for conspecifics. This study applies the source–filter theory to the acoustics of nasal, oral and nasal-and-oral calls that were recorded from a captive herd of 24 mother and 32 neonate saigas within the first 10 days postpartum. Anatomical measurements of the nasal and oral vocal tracts of two specimens (one per age class) helped to establish the settings for the analysis of formants. In both mother and young, the lower formants of nasal calls/call parts were in agreement with the source–filter theory, which suggests lower formants for the longer nasal vocal tract than for the shorter oral vocal tract. Similar fundamental frequencies of the nasal and oral parts of nasal-and-oral calls were also in agreement with the source–filter theory, which postulates the independence of source and filter. However, the fundamental frequency was higher in oral than in nasal calls, probably due to the higher emotional arousal during the production of oral calls. We discuss production mechanisms and the ontogeny of formant patterns of oral and nasal calls among bovid and cervid species with and without a trunk-like nose.
 
Psychoacoustic laboratory studies with live dolphins require considerable resources and are essential for assessing the validity of our models. Computerized numerical modelling methods are a reasonable approach to simulate the vibroacoustic functions of the dolphin biosonar apparatus. In order to validate this approach, we chose a vibroacoustic finite element model to simulate sound production and sound beam formation in the bottlenose dolphin (Tursiops truncatus), based on computed tomography scans from live and postmortem dolphins. The right and left dorsal bursae were assumed to be potential sound sources. The simulations confirm several hypotheses: (1) the shape of the skull plays a role in the formation of the sound transmission beam; (2) the melon appears to concentrate the acoustic energy by a factor of four in the transmitted beam; (3) focusing the sound beam apparently occurs in a series of stages that include contributions from the skull, nasal diverticula, melon and connective tissue structures. An unexpected result is that adjustments to the focus and direction of the sound beam can result from small (millimetre scale) changes in the relative position of the anterior and posterior bursae within each sound generation complex. Comparing our results with those from dolphin psychoacoustic experiments establishes validation of our vibroacoustic model. The potential for varied effects from anthropogenic sound also emphasizes the importance of developing vibroacoustic modelling. These numerical modelling tools complement experimental data for determining exposure thresholds and may allow us to simulate exposure levels, from moderate to extreme, without impacting live animals. http://www.tandfonline.com/eprint/PJmP74kHgiIwkMXjuKuU/full
 
The aim of this paper is to investigate the extent of seismic exploration on a global scale and how this is changing. This is explored by splitting the available data from 1994 to 2004 into 8 regions. The data are difficult to interpret because of their varying quality. We conclude that future reporting should be standardised, mandatory and transparent throughout the industry to aid our understanding of the extent of seismic surveys globally and therefore the potential impact on marine fauna.
 
Acoustic signals are used in diverse social contexts by frogs and serve as relevant tools for studies on evolution, description and identification of species. Here, we described the advertisement, aggressive and release calls of Rhinella sebbeni, a poorly known toad from the Rhinella margaritifera species group. The description of the vocal repertoire of R. sebbeni was based on eight males from the municipality of Terezópolis de Goiás, State of Goiás, Brazil. Calling activity of R. sebbeni is crepuscular and calls consist of nonharmonic pulsed notes. The advertisement call classified as type II, had an average duration of 0.299 s and dominant frequency of 1,266 Hz. Aggressive call duration was 0.288 s and dominant frequency of 1,292 Hz. Finally, the release call duration was 0.021 s and dominant frequency 979 Hz. We found that advertisement call of R. sebbeni and its calling activity were similar to those of other species in the R. margaritifera group. We argued that release calls are useful for identification in this taxonomically complex group. We also emphasize the importance of acoustic and natural history data to help clarify the taxonomic status of species belonging to groups such as R. margaritifera.
 
In this study, we examined the temporal variation in calling activity of a field cricket, Acanthogryllus asiaticus on a diel and seasonal scale. We also examined the acoustic structure of calls produced in the context of mating, namely, long distance mating call (LDMC), courtship call and post copulatory call. Finally, we examined the allometric relationship between sound-producing structures and body morphometry and tested whether peak frequency of LDMC was indicative of male body size. Our findings suggest that calling activity of A. asiaticus peaked between 2100 and 2400 h on a diel scale and between March and May (summer) on a seasonal scale. The three calls were acoustically distinct and stereotypic with the courtship and post copulatory calls being composed of two chirp-types each. This study presents the first description of post copulatory calls of a field cricket. Morphometric analyses revealed that both inter-tooth distance and teeth width varied along the file length, however, number of teeth and file length were not correlated. Harp area was correlated with body size and peak frequency was significantly negatively correlated with harp area. This implies that the peak frequency can potentially be an indicator of body size in this species.
 
Top-cited authors
Thierry Aubin
  • French National Centre for Scientific Research
Jérôme Sueur
  • Muséum National d'Histoire Naturelle
Torben Dabelsteen
  • University of Copenhagen
Gustav Peters
  • Zoological Research Museum Alexander Koenig
Hanspeter Herzel
  • Humboldt-Universität zu Berlin