[Perception by teenagers and adults of the changed by amplitude sound sequences used in models of movement of the sound source].

The ability to evaluate direction of amplitude changes of sound stimuli was studied in adults and in the 11-12- and 15-16-year old teenagers. The stimuli representing sequences of fragments of the tone of 1 kHz, whose amplitude is changing with time, are used as model of approach and withdrawal of the sound sources. The 11-12-year old teenagers at estimation of direction of amplitude changes were shown to make the significantly higher number of errors as compared with two other examined groups, including those in repeated experiments. The structure of errors - the ratio of the portion of errors at estimation of increasing and decreasing by amplitude stimulus - turned out to be different in teenagers and in adults. The question is discussed about the effect of unspecific activation of the large hemisphere cortex in teenagers on processes if taking solution about the complex sound stimulus, including a possibility estimation of approach and withdrawal of the sound source.

[Tendencies in auditory physiology].

Main tendencies in studying of human and animals auditory system with psychoacoustical and electrophysiologycal methods are considered. Concerning psychoacoustical studies some basic data are presented as well as contemporary tendencies in hearing physiology in analysis of the intensity, frequency, temporal characteristics of the sound signals and data related to such phenomena as masking and adaptation. Data concerning directional hearing are presented in detail as a basis of auditory virtual reality. In electrophysiological studies of the auditory system detailed analysis of mapping in auditory centers and mechanisms concerning localization of unmoved and moving auditory stimuli was performed. Special attempt was paid to consider the reflection of different types of auditory signals in human evoked potentials.

[Dependence of the mouse inferior colliculus neurons activity on position and direction of movement of the spectral contrast]. / Aktivnost' neironov zadnego kholma myshi v zavisimosti ot polozheniia i napravleniia peremeshcheniia spektral'nogo kontrasta.

Response variability of the single neurons of the inferior colliculus of mouse (Mus musculus) to series of noise bands and of notch noises with regular 1/12 octave steps of the band/notch center frequency and width of noise band/notch 1/3 octave, was studied. Neurons with strong inhibitory influence in excitatory response area (inhibitory-dominated) show low impulse activity when noise band exceeded excitatory response area. Spectral contrasts crossing the center of excitatory response area (at CF or nearly CF) were found to be the most efficient stimuli for such neurons. Neuron responses to spectral contrasts derived both from noise band and noise notch were identical. Approaching of inhibitory and excitatory inputs is expected to sharpen the auditory neurons frequency tuning to position of spectral contrasts, similar to neuronal processing in visual system. Neuron selectivity to the direction of spectral contrasts movement was determined in neuron response differences when the noise band or notch shifted from excitatory area to inhibitory areas as compared with shift in the opposite direction. Functional role of contrast mechanism for sound localization on the base spectral cues related to external ear transfer characteristics is discussed.

[Sensitivity of the neurons in the auditory inferior colliculus of mice to the direction of the shift of broadband spectral notch noise]. / Izbiratel'nost' neironov slukhovogo otdela srednego mozga myshi k napravleniiu peremeshcheniia spektral'nykh vyrezok v shirokopolostnom shume.

Series of a notch noise with regular shifts of the notch center frequency: one--from low frequencies to high frequencies and the other--from high frequencies to the low, were synthesized. The notch noise series imitated sound source vertical moving. Single neuron's responses of inferior colliculus of the house mouse (Mus musculus) to the notch-noises altered with notch central frequency varying through excitatory and inhibitory frequency response areas in neurones' receptive fields. The neural responses alteration to the notch noise varying depended on the bandwidth of notch. Disinhibition in inhibitory side band could be higher if the notch overlying the inhibitory areas followed the notch overlying the excitatory areas. The data obtained make it possible to consider the excitatory and inhibitory interaction as a mechanism of neural sensitivity to the notch moving direction. Neurones' response set could provide information about sound source moving over auditory space.

[Auditory analysis of the sound source approaching and withdrawing: psychoacoustic and neurophysiological correlates]. / Slukhovaia otsenka priblizheniia i udaleniia istochnika zvuka: psikhoakusticheskie i élektrofizicheskie korreliaty.

The findings seemed to be based on direction and velocity of modelling the radial sound source shifting in free acoustic field. The threshold and the optimal parameters of the acoustic model imitating the approaching and withdrawing of the sound source shifting in silence and under conditions of noise, were established. A correlation between peak-to-peak amplitudes of the N1-P2 components of auditory EPs and the imitated direction of the sound shifting, was shown. The role of different left and right hemispheres' areas in perception of the radial sound source was analysed. The detector features of the central auditory neurones were shown as a possible mechanism of estimating the sound source approaching and withdrawal.

[Modeling the frontal closing and departure of sound source]. / Modelirovanie frontal'nogo priblizheniia i udaleniia zvukovogo istochnika.

Software modeling frontal back and forth movements of a sound allowed determination of the best combinations in which changes in amplitude and frequency of sound pulses sequence invoke distinct sensations of approaching or departing sound factually generated at one and the same spot no matter the distance from the listener.

[Characteristics of the response area of mouse inferior colliculus neurons within the critical band]. / Kharakteristika oblasti otveta neironov zadnego kholma myshi v predelakh kriticheskoi polosy.

The inferior colliculus neurons which characteristic frequencies are in the range of 17-25 kHz, corresponding in mice to the width of psychophysical critical band with central frequency of 20 kHz, revealed all types of rate/level functions traditional to the auditory system neurons: monotonic, plateau and non-monotonic. Simultaneous presentation of two tones provide the following effects in the neuron response area: threshold sensitivity shift to high intensities; the reduction of intensity range within the neuron frequency response area; the increase of neurons selectivity to the stimulus frequency parameters, cause not only restriction of response exhibitory area, but threshold decrease on the CF stimulus. The finding suggest a coexistence of two inhibitory systems, one of which provides the stability of auditory system's frequency selectivity in the wide intensity range and the other regulating perception of signal intensity within neuron frequency area.