Stiedl, O., Bickmeyer, U. & Kalmring, K. (1991). Tooth impact rate alteration in the song of males of Ephippiger ephippiger Fiebig (1991). (Orthoptera, Tettigoniidae) and its consequences for phonotactic behaviour of females. Bioacoustics 3(1): 1-16
Abstract
The syllables of the calling songs of many bushcrickets (Orthoptera, Tettigoniidae) are formed of a series of discrete sound impulses. Bioacoustic investigations of E. ephippiger revealed that in some males the number of impulses per main syllable fall from about 50 impulses down to 10 impulses with increasing age of the male after the final moult. An influence of the altered signal on the frequency content of the acoustic signal could not be proved as far as averaged spectra are concerned. The geriatric effect on the syllable pattern is caused by mechanical attrition of the peaks of the teeth forming the pars stridens.
Two-choice experiments revealed that females can discriminate between songs with modified impulse repetition rate and songs with the normal impulse repetition rate. The inter-impulse intervals in the modified song vary from 0.8 ms up to 8.7 ms. Experiments with stimuli formed of natural impulses with a constant repetition rate proved that females are able to discriminate between these signals over a certain range. A stimulus that contains an inter-impulse interval similar to the species-specific one (1.87 ms on average) is preferred to stimuli with altered (~> ± l ms) inter-impulse interval when broadcast alternately. When the impulse repetition rate is only slightly altered (~ < ± l ms) the females cannot discriminate between these signals behaviourally.
Johnsen, R., Espmark, Y., Pedersen, H.C. & Steen, J.B. (1991). Characteristics of territorial and mating calls in willow ptarmigan Lagopus l. lagopus. Bioacoustics 3(1): 17-30
Abstract
During territorial behaviour and pair formation willow ptarmigan cocks and hens use several different calls. Cocks use mainly a “flight call” a “ground call” and three different “threat calls”. Hens give similar calls to cocks. It is suggested that the structure of the calls is well adapted to (1) transmit their possible infomation content over long distances, and (2) make localization easier for birds during the territorial display periods, which take place mainly in poor light at dusk and dawn. We also suggest that the cock and hen calls express different degrees of aggressiveness, and that hen calls, in addition to attracting cocks, function as territorial “keep out” signals to other hens.
Brillet, C. & Paillette, M. (1991). Acoustic signals of the nocturnal lizard Gekko gecko; analysis of the "long complex sequence". Bioacoustics 3(1): 33-44
Abstract
Four types of vocalizations of the nocturnal lizard Gekko gecko (the 'Tokay') are described. A bark of intimidation, distress calls, a short not very intense call, apparently related to sexual inter-action, and a long, complex sequence. This ‘long sequence’ is considered to be a territorial proclamation which also functions as a mating-call. It has been analysed in detail with special emphasis on the intra-individual variations. The mean duration of this sequence is 22.3 s, the intensity is 70 dB at lm and the maximum of energy is between 300 and 4000 Hz. This sequence is composed of three phases. The first one consists of several multipulse sounds called 'rattles', the second of hi-motifs which sound like a two syllable tok-kay, and the third, not always present, is a kind of ‘grumble’. The number of motifs and the occurrence of the third phase may vary but the duration of the motifs is relatively stable.
Richard, J.-P. (1991). Sound analysis and synthesis using an Amiga micro-computer. Bioacoustics 3(1): 45-60
Abstract
This note presents a program for analysis and synthesis of sounds designed to be used with an Amigo micro-computer. The user is in real-time control of the capture of the signal with reference to both time and amplitude parameters. Subsequently the chosen signal can be edited and analysed. Sonograms can be obtained at three resolutions, both in time and frequency. Measurements of time can be made on the signal, of frequency on the sonogram and of amplitude on sections. Three functions for the extraction of the fundamental are available. A synthetic sound may be obtained, either by modifying the amplitude and frequency modulation of an existing sound, or by creating a new sound by additive synthesis. All the commands can be selected by using a mouse, and the program is user-friendly.
Hurly, T.A., Weisman, R.G., Ratcliffe, L. & Johnsrude, I.S. (1991). Absolute and relative pitch production in the song of the white-throated sparrow (Zonotrichia albicollis). Bioacoustics 3(2): 81-91
Abstract
The songs of white-throated sparrows consist of 5 notes of very pure tonal quality. In ascending song, the pitch increases substantially from Note 1 to Note 2; whereas, in descending song, pitch decreases substantially from Note 2 to Note 3. Variability in the absolute pitch of each note is considerable among birds, but much less within individuals. Analysis of the major pitch changes in these songs shows that the pitch interval (ratio of the higher to the lower frequency), a measure of relative pitch constancy, predicts the frequency of the higher note in the pitch change more precisely than does the difference between the frequencies of the two notes, a measure of absolute pitch constancy. We conclude that white-throated sparrows produce relative rather than absolute pitch constancy during the major frequency changes in their songs and suggest that pitch interval may be an important cue in species recognition.
Forrest, T.G. & Green, D.M. (1991). Sexual selection and female choice in mole crickets (Scapteriscus: Gryllotalpidae): modelling the effects of intensity and male spacing. Bioacoustics 3(2): 93-109
Abstract
Attraction of flying mole crickets to individual males calling in an outdoor arena was influenced significantly by the relative intensity of the males calling in the arena. Louder males attracted more individuals than males whose calling songs were less intense. Making simple assumptions about the acoustic output from calling males and about the flight pattern and response of flying females, the differential attraction can be explained by a mathematical model. Computer simulation of the model was used to examine the importance of a male's intensity relative to others and the effect of distance between males on the attraction of females. The model and its relation to active female choice and passive attraction are discussed. The model makes predictions about differences in spacing behaviour of males that maximize attraction relative to other males.
Mable, B.K. & Bogart, J.P. (1991). Call analysis of triploid hybrids resulting from diploid-tetraploid species crosses of Hylid tree frogs. Bioacoustics 3(2): 111-119
Abstract
Calls produced by hybrids resulting from laboratory crosses of tetraploid Hyla versicolor females and either diploid Hyla chrysoscelis (type 1) or Hyla arborea (type II) males were induced through manipulation of environmental conditions. Type I hybrids produced trilled calls similar in note repetition to H. versicolor, but more similar in dominant frequency to H. chrysoscelis. Mean duration was shorter than in both parent calls. Type II hybrids produced calls which were longer in duration and lower in note repetition rate than H. versicolor, but shorter in duration and higher in note repetition rate than H. arborea. Dominant frequency of type II hybrids was lower than in H. arborea but not significantly different than in H. versicolor. Hybrid calls were not strictly intermediate, and may provide information regarding parental relationships.
Williams, J.M. & Slater, P.J.B. (1991). Computer analysis of bird sounds: a guide to current methods. Bioacoustics 3(2): 121-128
Abstract
Bioacoustics researchers can use a computer as a powerful tool to measure, classify, compare and synthesize sounds. Vocalisations on tape are commonly converted to a digital format suitable for a computer by using an analogue to digital converter and then a Fourier transformation. Alternatively, sonograms can be measured, for example by using a digitizing pad or an image analysis system. Correlations and indices of similarity have been used to compare sounds, but variations in both the time and frequency dimensions of a noise are a problem. A solution may be the use of pattern recognition methods such as elastic matching and time warping. These methods are briefly described and assessed.
Okanoya, K. & Dooling, R.J. (1991). Detection of species-specific calls in noise by zebra finches Poephila guttata and budgerigars Melopsittacus undulatus: time or frequency domain? Bioacoustics 3(3): 163-172
Abstract
Two zebra finches and two budgerigars were trained, by operant conditioning, to detect autogenous (self-generated) distance calls in the presence of masking noise. For both species, there were no differences in detection thresholds for normal calls compared to time-reversed calls. Thresholds for autogenous calls were also compared with thresholds of the other species of birds listening to the same call. When detecting a zebra finch call, budgerigars had slightly lower thresholds than that of the zebra finch. On the other hand, when detecting a budgerigar call, zebra finches showed significantly higher thresholds than the budgerigar. From these results, and from what is known about basic hearing capabilities in these species, we conclude that these birds are not using a mechanism which utilizes “matched'' or cross-correlational filtering. It is more likely that they are using “frequency-based'' filtering in detecting calls in noise.
Fonseca, P.J. (1991). Characteristics of the acoustic signals in nine species of cicadas (Homoptera, Cicadidae). Bioacoustics 3(3): 173-192
Abstract
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.
Dabelsteen, T. & Pedersen, S.B. (1991). A portable digital sound emitter for interactive playback of animal vocalizations. Bioacoustics 3(3): 193-206
Abstract
A new portable digital sound emitter (DSE) for normal and interactive playback of sound signals in the field and in the laboratory is described together with two examples of applications of the DSE in interactive field experiments. The DSE may be loaded with a broad spectrum of digitized sounds, e.g. artificial signals or natural animal vocalisations, and it is controlled via the keyboard of a portable PC running a dedicated program. This program, which can be tailored to support a vast number of different demands, enables the experimenter to start and stop the analog output from the DSE at any time and to choose freely between the available sounds and playback modes. The use of the DSE for interactive playback experiments therefore is only limited by the ability of the operator to perceive the vocalisations of the participating animal and to operate the keyboard of the PC.
Thielcke, G. & Krome, M. (1991). Chaffinches Fringilla coelebs do not learn song during autumn and early winter. Bioacoustics 3(3): 207-212
Abstract
According to the literature, young chaffinches learn conspecific song during the first ten months of their lives. We have shown here that under natural light conditions captive birds do not learn song in October and November and that only one out of ten males was able to learn in December/January. This gap in the ability to learn from first summer to the beginning of the second calendar year is not age-dependent but seems to be hormonally controlled.
Pailette, M., Ikeda, H. & Jallon, J.-M. (1991). A new acoustic signal of the fruit-flies Drosophila simulans and D. melanogaster. Bioacoustics 3(4): 247-254
Abstract
We found 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 behaviour of mature males who emit ‘pulse songs’ (i.e. love song: LS). It occurs most frequently in si, less in adults me except if the interacting males belong to different chemical morphs (i.e. temperate or equatorial population). There are no differences in the LS characteristics directed to various sexes and ages. The RSs produced by adult males or by young animals do not differ significantly either. 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 sound level of the RS is from 10 to 20 dB less than the LS. The RS seems to be linked to the ‘flicking’ behaviour produced by both wings, while the LS always corresponds to the so-called ‘wing vibration’.
Popp, J. & Ficken, M.S. (1991). Comparative analysis of acoustic structure of passerine and woodpecker nestling calls. Bioacoustics 3(4): 255-274
Abstract
We examined the acoustic structure of the calls of 71 species of nestling passerines (both suboscines and oscines) and 4 species of nestling woodpeckers. Calls varied greatly in general acoustic structure, frequency (pitch) and duration. Some phylogenetic trends occurred, e.g. calls of woodpeckers and suboscines tended to be simpler than those of most oscines. Body size was significantly correlated with both maximum and minimum frequency. Age-related changes occurred in some species but not others. The results suggest some phylogenetic and developmental constraints on call structure, but do not rule out the possibility that selection acts directly on nestling calls. However, the hypothesis that cavity-nesters would have more easily localizable calls than open-nesters because of lowered predation risk was not supported by our study, which showed no significant differences in any frequency or temporal measures of acoustic structure between cavity-nesters and open-nesters.
Coscia, E.M., Phillips, D.P. & Fentress, J.C. (1991). Spectral analysis of neonatal wolf Canis lupus vocalizations. Bioacoustics 3(4): 275-293
Abstract
Timber wolf Canis lupus pups vocalize within hours of birth. In this report we examine aspects of the acoustical structure of these vocalizations. We installed an unobtrusive monitoring system in a den excavated by a group of pack-reared timber wolves at the Dalhousie Animal Behavior Field Station in order to observe and record at close range the activities of a female wolf with her litter of pups. We obtained audio and video recordings from birth through the first six postnatal weeks, 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 two dimensions were necessary to classify vocalizations. The most common sounds, present as early as day one, 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 second postnatal week.
Elowson, A.M. & Hailman, J.P. (1991). Analysis of complex variation: dichotomous sorting of predator-elicited calls of the Florida scrub jay. Bioacoustics 3(4): 295-320
Abstract
The acoustically complex predator-elicited calls of the Florida scrub jay Aphelocoma c. coerulescens were classified operationally by a new procedure, dichotomous sorting. Vocalizations were tape-recorded in the field 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. Univariate frequency-of-occurrence histograms and bivariate scatter plots were used to locate distributional breaks or separations that established dichotomous subdivisions of the data set. The analytical steps were repeated on each subsequent subset of calls. Some variables that appeared graded by visual inspection were distinctly discontinuous and defined call types. Hierarchical Cluster Analysis (HCA) 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. The criteria can be applied much like a dichotomous key to classify other scrub jay call data sets, and the methodological strategy is widely applicable to acoustical communication systems in general.