“…Hyrax song complexity is not thought to contain contextual information beyond male fitness (Koren & Geffen ; Demartsev et al . ), although this assumption is currently untested. In contrast, dolphin signature whistles are known to be individually distinctive whistles that can be identified by the unique pattern of frequency modulations (Janik, Sayigh & Wells ).…”
n-gram models, repeat distribution, and edit distance), and data generated by different stochastic 30 processes (entropy rate and n-grams). However, the string edit (Levenshtein) distance performed 31 consistently and significantly better than all other tested metrics (including entropy, Markov 32 chains, n-grams, mutual information) for all empirical datasets, despite being less commonly used 33 in the field of animal acoustic communication.
“…Hyrax song complexity is not thought to contain contextual information beyond male fitness (Koren & Geffen ; Demartsev et al . ), although this assumption is currently untested. In contrast, dolphin signature whistles are known to be individually distinctive whistles that can be identified by the unique pattern of frequency modulations (Janik, Sayigh & Wells ).…”
n-gram models, repeat distribution, and edit distance), and data generated by different stochastic 30 processes (entropy rate and n-grams). However, the string edit (Levenshtein) distance performed 31 consistently and significantly better than all other tested metrics (including entropy, Markov 32 chains, n-grams, mutual information) for all empirical datasets, despite being less commonly used 33 in the field of animal acoustic communication.
“…; Demartsev et al. ). Wild rock hyraxes were trapped using live box traps (Tomahawk Live Trap Co, USA) baited with cabbage and kohlrabi.…”
Section: Methodsmentioning
confidence: 97%
“…) that function as a quality advertisement signal (Koren and Geffen ; Demartsev et al. ). Male songs presented a conceptual challenge in determining the relevant classification unit.…”
Section: Methodsmentioning
confidence: 99%
“…The songs are composed of three distinguishable vocal elements that are arranged in up to 90 singing bouts, separated by a silent interval of ∼1 s (Demartsev et al. ). Previous analyses have considered songs both as single units (Ilany et al.…”
The efficiency of informational transfer is one of the key aspects of any communication system. The informational coding economy of human languages is often demonstrated by their almost universal fit to Zipf's “Law of Brevity,” expressing negative relationship between word length and its usage frequency. Animal vocal systems, however, provided mixed results in their adherence to this relationship, potentially due to conflicting evolutionary pressures related to differences in signaling range and communicational needs. To examine this potential parallel between human and animal vocal communication, and also to explore how divergent, sex‐specific, communicational settings affect signaling efficiency within a species, we examined the complete vocal repertoire of rock hyraxes (Procavia capensis). As male and female hyraxes differ in their sociality levels and male hyraxes vocal repertoire is dominated by sexual advertisement songs, we hypothesized that sex‐specific vocal repertoires could be subjected to different signaling optimization pressures. Our results show that the sexes differ in repertoire size, call usage, and adherence to coding efficiency principles. Interestingly, the classic call length/call usage relationship is not consistently found in rock hyraxes. Rather, a negative relationship between call amplitude and call usage is found, suggesting that the efficiency of the vocal repertoire is driven by call amplitude rather than duration. We hypothesize that, in contrast to human speech that is mainly intended for short distance, the need for frequent long‐range signaling shapes an animal's vocal repertoire efficiency according to the cost of call amplitude rather than call length. However, call duration may be a secondary factor affecting signaling efficiency, in cases where amplitude is under specific selection pressures, such as sexual selection.
“…Signallers are attuned to the state of their audience and attempt to time their performance to periods of increased listener attention 27 . Moreover, males increase the overall rhythm and complexity of their songs in the presence of an alert audience 20 . Until now, the analysis of hyrax songs has been based on discrete measures of spectral parameters or on the composition of the different vocal elements within a song.Figure 1( a ) Proposed musical notation of male song corresponding to the parts represented in the spectrogram.…”
The study of animal vocal signals can either focus on the properties of distinct vocal elements or address the signal as a whole. Although some attention has been given to the continuous progression patterns of bird songs, such patterns in mammalian vocalisations have been largely overlooked. We examined temporal changes in structural and acoustic parameters in male rock hyrax songs. We found a gradual increase in call frequency and amplitude towards the song ending, as well as an abrupt increase in bout syntactic complexity, peaking in the last quintile of a song. In musical terms, such a pattern can be described as a crescendo (amplitude increase) with a terminal climax. In Western music, crescendos are used to maintain attention and direct the listeners towards a memorable highpoint of the musical piece. This structure may have an analogous function in animal communication, recruiting audience attention towards the climactic and potentially most informative part of the signal. Our playback experiments revealed that hyrax males tend to reply more to songs with a climactic ending, indicating that this progression pattern is important for hyrax communication. We suggest that animal vocal communication research can benefit from adding musical concepts to the analysis toolbox.
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