Using objective methods of formal analysis revealed fundamental similarity of audio signals of several types of apes and monkeys, i.e. chimpanzees, rhesus monkey, baboon, siamang (gibbon) with manifestations of emotions in human speech.
It is shown that the developed system (based on the principle of the relative crossfrequency amplitude-variable encoding) of formal parameters for assessing emotions in human speech is well applied as an experimental procedure for objective evaluation and interpretation of beeps monkeys (in accordance with the system of human emotions). This is confirmed by corresponding formal assessments with observations of animal behaviour in different situations.
The proposed anthropomorphic method of analysis of audio signals animals is based on four-dimensional spherical model of human emotions and principles of information encoding in the nervous system. The proposed model can serve as a common classification system for emotional phenomena that combines both physiological concepts of brain mechanisms of emotional control, and psychological well-known classification based on diverse experimental data. It also quantitatively explains all possible nuances and soft emotion mutual transitions, with representing each specific emotion as a linear combination of the selected basic physiological parameters. Positive agreement between the parameters of the speech signal in not only humans but also monkeys with psychophysiological parameters confirm the theoretical issues of the principles of encoding information in the nervous system and efficiency of the proposed anthropomorphic approach to the development of technical systems, in particular methods for speech signal processing. On the other hand, the coincidence of the detected pattern confirms the previously identified psychophysiological parameters, which further substantiate preference (compared with others described in the scientific papers) reveals in a classification system of emotions in terms of both the dimension and orientation of the axes in relation to the model space.
On the whole, the results suggest that the emotional regulation system is very old and preserved in humans without change throughout history and co-existing with the system of feeling expression and also with the independent speech sound system. Furthermore, it is shown that in the majority of the surveyed types of apes and monkeys (chimpanzees, rhesus monkey and baboon), the entire repertoire of sound signals is reduced to the above mentioned emotional regulation. However, we that some types of apes and monkeys, e.g. siamang (gibbon), are able to diverse their repertoire of sound signals and create additional channels of sound signals in a relatively free frequency domain, so as not to interfere with the system of signals shared with other types of apes and monkeys (and also humans). Apparently, this additional sound system is based on the same encoding principle as the general emotional system.