Vol 38, No 2 (2024)

One of the main functions of sensory systems is the implementation of intraspecific communication, which often occurs through the exchange of communication calls. It is quite natural that the hypothesis arises that the radiation and reception of these signals should be coordinated. There is usually a certain similarity in the characteristics of specific communication sounds and the receiving devices of an auditory analyzer. However, the degree of such correspondence in the neural structures of the brain remains a subject of debate. The review examines studies aimed at solving the issue of specialized encoding of such signals in the brains of various terrestrial vertebrates, ranging from tailless amphibians to primates. For decades, researchers have been searching for neurons in the direct auditory pathway that could serve as detectors of communication signals. However, an analysis of the extensive literature does not reveal the existence of any clearly defined area of the direct auditory pathway that would be specialized for analyzing this category of sounds. It seems that the functional significance of the neurons of this pathway consists of highlighting many features of the temporal flow within the entire perceived spectral composition of sound. This process is carried out on the trained synaptic connections in the process of permanent evolution, determined by the sensory environment. Dynamically organized ensembles of neurons can be formed in the central parts of the direct auditory pathway, synchronously reacting to the action of a certain sound. It is precisely such ensembles that can be considered as output structures of an auditory analyzer, which can determine the perception and the corresponding motor reactions.

The peripheral photoreceptor system of adult insects and insect larvae of hemimetabolous insects consists of a pair of compound facet eyes and several simple chamber eyes, the ocelli. The origin of the ocelli is attributed to the simple eyes of crustacean larvae; the ocelli, along with the compound eyes, present the basic plan of the photosensitive system of insects. The evolution of these light-sensitive organs is closely related to flight, allowing to maintain the position of the body in relation to the horizon, they have high sensitivity and fast signal processing, which is critical for small animals easily carried away by air currents. In low light conditions, ocelli increase in size and in some cases also increase light sensitivity through light-reflecting tapetum, loss of polarization sensitivity and color separation. When light intensity is reduced below a critical level, such as in cave dwellers, ocelli disappear. In actively moving diurnal insects, ocelli can acquire polarization sensitivity, features of object vision, and several, mostly two, spectral types of photoreceptors. The high speed of the ocellar visual system is ensured by a small number of synaptic connections projecting to motor circuits.

Psychophysical methods were used to study the features of identifying the gender of a speaker based on voice characteristics under conditions of speech-like interference and stimulation through headphones. We used a set of speech signals and multi-talker noise from experiments in a free sound field – a spatial scene (Andreeva et al., 2019). The set included 8 disyllabic words spoken by 4 speakers: 2 male and 2 female voices with average fundamental frequencies of 117, 139, 208 and 234 Hz. Multi-talker noise represented the result of mixing all audio files (8 words * 4 speakers). The signal-to-noise ratio was 1:1, which subjectively corresponded to the maximum noise level in the spatial scene (SNR = –14 dB). Adult subjects from 17 to 57 years old (n = 42) participated in the experiments. Additionally, 3 age subgroups were identified: 18.6±1.5 years (n = 27); 28±4.1 years (n = 7); 46±5.4 years (n = 8). All subjects had normal hearing. The results of the study and their comparison with the data of mentioned work confirmed the importance of voice characteristics for the auditory analysis of complex spatial (free sound field) and non-spatial (headphones) scenes, and also demonstrated the role of mechanisms of the masking and binaural perception, in particular, the high-frequency mechanism of spatial hearing. A relation the perceptual assessment of the gender by voice in noise and the age of the subjects and the gender of the speakers (male/female voice) was also found. The results are of practical importance for the organization of hearing-speech training, early detection of speech hearing interference immunity impairment, as well as the development of noise-resistant systems for automatic speaker verification and hearing aid technologies.

An approach to a projectively invariant description of a family of ovals (o) in scenes where the figure o is given in a composition with an external point, P, fixed in its plane is considered, and in cases where o has hidden symmetries (central or axial), the position of P is not specified in the form of an additional condition defining the scene, but can be calculated through the symmetry parameters. The invariant description, as a general universal method for numerical processing of compositions like “o + ext-P”, is proposed to be implemented in the form of Wurf mappings.The method uses the apparatus of dual pairs (DP) and wurf functions,previously developed and described by us, which are a product of decomposition of statements of the reciprocity theorem proposed by J. Plьcker to describe the properties of quadratic curves (conics).Illustrated examples of special cases of the “o + ext-P”composition are considered and discussed, actually completing the topic of studying the scenes like “an oval and a linear element of the plane”, which are classified according to the types of symmetry of o.