Vol 37, No 3 (2023)

The review presents current methods used for researches of the auditory distance perception. The monaural and binaural cues of stationary and moving sources localization are considered. The role of binaural hearing in estimating the distance to a sound source is discussed in detail. The involvement of localization cues in absolute and relative distance estimation is described. The advantages and limitations of different experimental practices for forming virtual sound images are discussed. The special section discusses approaches to the creation of moving sound images. The results of auditory distance estimations obtained by different methods for stationary and moving sound sources are summarized. The review includes the results of the authors' own studies and a description of promising experimental and applied approaches of this research field.

As is known, the main indicators of the stable functioning of fusion mechanisms – the physiological basis of binocular perception – are the fusion reserves (FR), an accurate assessment of which is still problematic. To measure the FR, a small mismatch between the accommodation and vergence systems is introduced and gradually increasing to reach certain critical angles at which the fusion mechanisms cease to function, as judged by the subjective sensations of the subjects reporting the break of the binocular image into two monocular ones. The subjectivity of such assessments of FR, as well as poorly studied dependence of FR on the parameters of test objects and measurement procedures, make it difficult to determine standard values and to create databases on RF. To overcome these shortcomings inherent in traditional methods of measuring RF, at the end of the last century, attempts were made to use computer methods (Rozhkova et al., 1996 ab, 1998). This article presents the results of a critical evaluation of the computer method for measuring FR using the author’s interactive computer program FUZIYA (Bolshakov, Rozhkova, 2013), which provides for the generation of variable test images on a special display designed for the polarization method of separating the left and right channels of test object presentation. The purpose of this study was to evaluate the accuracy and reproducibility of the measurement results, as well as to test the effectiveness of the previously proposed method to programmatically provide objective control of the binocular image break. The data obtained confirm the prospects of the approach used and make it possible to clarify the specific forms of its rational application.

We aimed at demonstrating the direct physiological effects of octopamine on the auditory responses of the Johnston’s organ sensory neurons in Culex pipiens pipiens mosquitoes. Responses to acoustic stimulation were measured as the frequency-threshold curves and as an instantly recorded autoexcitation frequency before and after the injection of octopamine (or chlordimeform, an agonist of octopamine receptors). The autoexcitation frequency was assessed by including the auditory neurons into a positive feedback loop, when the amplified neuronal response was used to drive the stimulating loudspeaker. Our results indicate that: octopamine affects the properties of the auditory system both in male and female mosquitoes; in female mosquitoes, octopamine significantly reduces the sensitivity of auditory neurons below 90 Hz and produces little effect in the high-frequency range (100 Hz and above); in male mosquitoes, octopamine significantly raises the tuning frequency of the auditory system (ratio of tuning frequencies before and after the injection 1.32–1.55). There is a strong sexual dimorphism in the octopaminergic modulation of the mosquito auditory system. The observed physiological effects of octopamine, both in male and female mosquitoes, cannot be fully explained by the modulation of mechanical stiffness of the antenna and must include the changes in frequency tuning of the auditory neurons.

Frequency resolving power (FRP) of hearing was measured in listeners 30 to 82 years old as a maximal resolved ripple density (ripples/oct) of rippled-spectrum signals. The rippled-spectrum signal should be distinguished either from another rippled signal with different positions of ripples on the frequency scale or from a “flat”-spectrum signal with no spectral ripples. Signals had either 2-oct wide frequency band centered at 1, 2, or 4 kHz, or had a wide frequency band 0.125–8 kHz. Listeners older than 60 had substantially increased tonal thresholds (haring loss). If the listener should distinguish a rippled test signal from a rippled reference signal, FRP correlated with the tonal threshold: the higher threshold, the lower FRP. For all the signals, the trend of the dependence was from –0.04 to –0.07 ripples/oct·dB. It is suggested that in this case, the test and reference signals were discriminated by the spectral mechanism and depended on the interrelation between the ripple density and acuteness of the frequency-tuned filters. If the listener should distinguish the ripple test signal from a flat reference signal, the FRP dependence on tonal threshold was not statistically significant for 2-oct-wide signals on condition that the signal level was above threshold. Or the wide-band signal, the FRP dependence on tonal threshold was statistically significant with a trend of –1.23 ripples/oct·dB. It is suggested that in this case, the test and reference signal were discriminated by the temporal-processing mechanism and depended on the perceived frequency range.