摘要:

The computer-aided analysis of acoustic signals of mammals is still a problem, as ofte (a) sound structures are complex, (b) vocal repertoires often comprise an enormou variety of vocalisations, (c) recordings are influenced by the acoustic conditions of th environment, and (d) the distance and spatial orientation of the sender to th microphone changes. In recent software packages for the analysis of acoustic signal procedures are integrated which allow the calculation of a variety of signal feature: However, these algorithms are often problematic under the conditions mentioned abovi In this paper, we present a multi-parametric approach which reduces these problem and which allows a quantitative and reproducible analysis of complex animi vocalisations. Our approach comprises the following aspects: (1) reduction of influence of recording conditions, (2) determination of different sound features and (3) calculatio of parameters to characterise these sound features. All calculations are done on the bas: of the digitised spectrograms. Special attention is given to the use of smoothin algorithms and dynamic thresholds in order to estimate sound features and to reduc influences resulting from recording conditions. The suitability of our approach has bee demonstrated successfully for vocalisations of different species.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753338

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A unique up-slurred call of the willow titParus montanus, renderedpuiorplui, was discovered at a locality in the birch alpine region of central Norway in the summer of 1987 when three neighbouring pairs shared this call. Up to 1996 inclusive an additional number of 19pui-calling individuals were found. Typically, these birds were either offspring of birds already uttering the call, or members of winter flocks in which the dominant adults possessed the call. The call is evidently acquired by learning and serves as an alternative alarm call. It is suggested that rudimentary pui-calls are a normal component in babbling series of young willow tits in general and that the development of these into full calls depends on appropriate tutors. It should be emphasized that the pui-call does not replace another call in the repertoire, but is an extra call adding to the repertoire. It is probably the first time that such a phenomenon has been reported in birds. The expectation that the call would spread in the population has so far proved wrong.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753339

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The voices of 8 hinds and their 7 offspring were analysed spectrographically. They were transformed into sonograms and the following parameters were measured: duration, fundamental frequency and frequency bands with high amplitudes. The animals emitted single calls or a series of sounds at irregular intervals. The single calls were monosyllabic and the series were homotypical sequences. The hind voices were deep and bleatlike, ranging in frequency from 70 to 3000 Hz. The fundamental frequency was 108.35 ± 15.21 Hz and the duration was 0.27 ±0.14 sec. There were 1 to 8 frequency bands with high amplitudes created. Differences between individual voices were found in all characteristics of vocalization tested. The variation between voices was a result of the combination of these characteristics. The most important factor seemed to be the pattern of main frequency bands with high amplitudes. The calf voices were high, whiny and tonal, ranging in frequency from 320 to 7000 Hz. The fundamental frequency was 736.97 ± 177.67 Hz and the duration was 0.26 ± 0.12 sec. They were similar to each other, and inter-individual variation was not very apparent. This suggests that while hinds can be recognized individually by voice, it is probably not possible to distinguish the calves by voice alone. This is in accordance with parallel findings, that hinds did not seem to recognise their own calfs voice.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753340

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Although much research has been done to describe the degradation of sound signals propagating in natural habitats, the directional cues of sound have so far been neglected. This paper describes a first approach to quantifying the degradation of directional cues in sound propagating parallel to the ground in a grassland habitat of orthopteran insects. A matched pair of probe microphones measured the sound amplitude and phase close to the ears of grasshopper carcasses for 12 evenly spaced directions of sound incidence. The degradation was found to increase with frequency and distance from the sound source and to decrease with distance from the ground. The acoustical data were used to predict how well animals with different auditory systems can determine the direction of the sender. At one position in the habitat, the predictions were compared with the pattern of phonotactic responses of live grasshoppers. Amplitude cues appear to degrade much faster with distance than phase cues. Animals exploiting phase cues may therefore maintain a reasonable directional hearing when the amplitude cues no longer make sense. The pressure-difference-receiver type of ears responds to phase differences, and these ears may be particularly suited to overcoming the degradation of directional cues. This suggests that the possession of such ears may be an adaptation not only to small body size (relative to wavelength), but also to the acoustic properties of the habitat.

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753341

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753342

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753343

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753344

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753345

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753346

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0952-4622    

DOI:10.1080/09524622.1997.9753347

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor