The harmonic-to-noise ratio applied to dog barks.

Dog barks are typically a mixture of regular components and irregular (noisy) components. The regular part of the signal is given by a series of harmonics and is most probably due to regular vibrations of the vocal folds, whereas noise refers to any nonharmonic (irregular) energy in the spectrum of the bark signal. The noise components might be due to chaotic vibrations of the vocal-fold tissue or due to turbulence of the air. The ratio of harmonic to nonharmonic energy in dog barks is quantified by applying the harmonics-to-noise ratio (HNR). Barks of a single dog breed were recorded in the same behavioral context. Two groups of dogs were considered: a group of ten healthy dogs (the normal sample), and a group of ten unhealthy dogs, i.e., dogs treated in a veterinary clinic (the clinic sample). Although the unhealthy dogs had no voice disease, differences in emotion or pain or impacts of surgery might have influenced their barks. The barks of the dogs were recorded for a period of 6 months. The HNR computation is based on the Fourier spectrum of a 50-ms section from the middle of the bark. A 10-point moving average curve of the spectrum on a logarithmic scale is considered as estimator of the noise level in the bark, and the maximum difference of the original spectrum and the moving average is defined as the HNR measure. It is shown that a reasonable ranking of the voices is achievable based on the measurement of the HNR. The HNR-based classification is found to be consistent with perceptual evaluation of the barks. In addition, a multiparametric approach confirms the classification based on the HNR. Hence, it may be concluded that the HNR might be useful as a novel parameter in bioacoustics for quantifying the noise within a signal.

Nonlinear phenomena in the natural howling of a dog-wolf mix.

It was reported to the first author that a female dog-wolf mix showed anomalously rough-sounding vocalization. Spectral analysis of recordings of the vocalization revealed frequency occurrences of subharmonics, biphonation (two independent pitches) and chaos. Since these nonlinear phenomena are currently widely discussed as integral to mammalian vocalization [Wilden et al., Bioacoustics 9, 171-196 (1988)] or as indicators of vocal pathologies [Herzel et al., J. Speech Hearing Res. 37, 1008-1019 (1994); Riede et al., Z. Sgtkde 62 Suppl: 198-203 (1997)], we sought to understand the production mechanism of the observed vocal instabilities. First the frequency of nonlinear phenomena in the calls was determined for the female and four additional individuals. It turned out that these phenomena appear, but much less frequently in the repertoire of the four other animals. The larynges of the female and two other individuals were dissected post mortem. There was no apparent asymmetry of the vocal folds but a slight asymmetry of the arytenoid cartilages. The most pronounced difference, however, was an upward extension of both vocal folds of the female. This feature is reminiscent of "vocal lips" (syn. "vocal membranes") in some primates and bats. Spectral analysis of the female's voice showed clear similarities with an intensively studied voice of a human who produces biphonation intentionally. Finally, the possible communicative relevance of nonlinear phenomena is discussed.

Coalition formation among male Barbary macaques (Macaca sylvanus).

A coalition is formed when one animal intervenes in an ongoing conflict between two parties to support one side. Since support of one party is also an act against the other party, coalitions are triadic interactions involving a supporter, a recipient, and a target. The purpose of this study was to test which of three possible theories explains coalition formation among male Barbary macaques: 1) Males support kin to enhance their indirect fitness (kin selection). 2) Males support nonkin to receive future reciprocal support (reciprocal altruism). 3) Males pursue self-interests and immediately benefit via nonkin support (cooperation). Coalition formation was investigated among 31 semi-free male Barbary macaques in the Salem Monkey Park, Germany during the mating season. The results show: 1) Males intervened more often in dyadic conflicts in which a related opponent was involved and supported related opponents more than unrelated opponents. Close kin supported each other more often than distant kin. 2) Some evidence for reciprocal support was found. However, reciprocity was probably a by-product of targeting the same individuals for dominance. 3) Coalition formation among nonkin is best interpreted as cooperation, based on self-interests. Male Barbary macaques seem to intervene more often to stabilize and less often to improve their rank. Although our data were limited, the results revealed that kin support, reciprocal support, and cooperative support were all involved in coalition formation among male Barbary macaques.

[Human ontogenesis from a behavioral biological viewpoint]. / Humanontogenese aus verhaltensbiologischer Sicht.

General aspects of the human ontogenesis are analyzed theoretically from the view point of behavioural biology. The functional integration of the three levels of individual development--actual genesis, ontogenesis, phylogenesis--leads the author to the term "hologenesis". Based on the concept of hologenesis developmental problems are discussed in terms of behavioural biology. In this context behaviour is defined as the organismic interaction with the environment on the basis on information of the hologenetic process. Behavioural data on fetal, neonatal, and postnatal life are discussed in relation to interaction with the peristatic milieu.

Mimicry and crypsis - a behavioural approach to classification.

Mimetic strategies are characterized by interference in information processes, whereby certain signalreceivers are deceived by a mimic. The function of mimetic behaviour as well as of other behavioural patterns which have evolved is to satisfy the needs of the environment. Therefore it would seem justified to classify the phenomena of mimicry and crypsis on the basis of the aims which mimics have. Furthermore, several ethological ideas and terms of the organism-environment-interrelationships (irrelevant and relevant environment; communicative and information environment) are investigated to find out whether they are suitable to characterize and define animal and plant imitations. There are at least three complexes of mimetic strategies:

Choice of side of resting position in Vulpes vulpes (L.).

In fifteen foxes held under laboratory conditions all behaviour data recorded were tested according to the foxes' resting positions and especially as to the direction in which the body lay curled up (to the right or the left). 29 055 single items of data could be extracted and processed statistically. All individuals taken together show a significant preference for the right direction in the resting position. If the data are separated according to sex the statistical significance is restricted to the males. The difference between males and females is significant. The analysis indicated individual differences; individual disposition with regard to preference for one side seems plausible. Statistical testing of the foxes by twos indicated variations correlated with the biosocial status. The dominance value is positively correlated with the tendency to prefer a resting position to the left. There are significant differences between two times of day (09.00-11.00; 17.00-19.00 h) and two times of year (December-March; June-August) with respect to the type of behaviour studied. These differences refer to mean values and variance.

Canid vocalizations.

The classification of acoustic signs is related to four aspects, the phonetic, the syntactic, the semantic, and the pragmatic. Canid vocalizations can be subdivided into 10 classes, which are described. The meaning and functions are considered in respect to releasing functions, control functions (in the cybernetic sense) and in relation to metabolism, reproduction and territory. Examples are given of age-specific sounds and of sound ontogeny. In addition, the metrics (entropies of information) are demonstrated in an example of sound sequence in the dog.

[Biological basis of behavior regulation]. / Biologische Grundlagen der Verhaltensregulation

A changing of the information is taken as basis for the behaviour of the organism. While the metabolism produces a connective relation with the environment, the changing of the information delivers an informational relation. The two processes are essential constituents of the organism as an open system for the maintenance and the increase of the negentropy. The informational connection with the environment is primarily non-communicative (the recipient performs the verification of the meaning of the signs with meaning). On the basis of the changing of information three environments may be differed: (1) the own environment (telereceptoric informations on the own body), (2) the informational environment and (3) the communicative environment (common alphabet). The most important determinants of the behavior which connect the organism with its informational environment are pretensions to space, time, metabolism and changing of form. In the communicative environment there may be pretensions to territory, sex, care and social ones. In organism the behaviour is above all determined by vigilance, emotion, motivation, memory (storage), selector (and receptor) as well as operator (and effector). The comparative behavioural sciences allow certain universal evidence on the basis of such parameters. Here also constituents of the human behaviour can be seized.