Occurrence of nonlinear phenomena in Siberian and Neva Masquerade cats? vocalisation
Résumé
Cats speak by using complex combinations of body language, vocalization, and scent cues. Cats have been regarded for centuries as mysterious, solitary, unpredictable creatures, perhaps because humans have difficulty understanding what they're saying. One of the acoustic parameters where the information for another individual can be encoded are nonlinear phenomena (NLP). This term refers to a set of vocal features which are normative events in mammalian vocalisations, being directly traceable to the nonlinear nature of vocal folds dynamics. Nonlinear phenomena are now emerging as a common occurrence in mammals. Although NLP are widespread, very little is known about their function. It has been suggested that nonlinear phenomena increase the individual distinctiveness of vocalizers, boost the auditory salience and impact of vocalizations on listeners, or have no specific function but provide cues as to vocalizer fitness. The purpose of this work was to check whether the NLP occur in cats? communication, and whether individual features and situation influence them. Vocal recordings from 20 adult Siberian Cats and 10 Neva Masquerade cats were collected and used in a phonetic study in order to test some recording and analysis methods. Cats' responses to behavioural stimuli in two test situations were recorded: vocalization before serving food and isolation calls (closing the cat in a cage for 3 minutes). Vocalizations were detected and segmented, with voiced and unvoiced vocalizations being differentiated. The recordings were processed using PRAAT, Raven Pro and Audacity software. The vocalizations were analysed for subharmonics, biphonation, deterministic chaos, frequency jumps, bursts, non-tonal moments or any subset of these events.
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