Localization of sound sources. Theoretical foundations and results of experimental investigations

Auditory localization is one of the elements of spatial orientation systems. It helps to evaluate the surrounding environment on the basis of acoustic information. Directional hearing is important at the time of considerable development of mechanization and urbanization. It applies to all the people, but in particular to people with impaired hearing organs. This work consists of two basic parts. The first part, which has the form of a monograph, theoretical foundations of spatial hearing and a wide range of problems related to sound source localization have been presented. The second part is experimental in nature. It includes a description of the methodology and results of investigations aimed at defining the ability of directional hearing in people with normal hearing, women and men, aged
18-28. This is the first stage of investigations aimed at defining the localization abilities of hearing impaired people with no hearing aid or with hearing aids, cochlear implants or mixed implantation. Its main objective is to determine the usefulness of different types of acoustic signals in such investigations. Tonal signals, 1/3 octave band noise and amplitude modulated 1/3 octave band noise were applied, with frequencies of 500 Hz, 1000 Hz and 4000 Hz, at the signal level of 80 dB SPL. Application of noise signals was motivated by the desire to approximate signals that are more representative than tonal ones for the surrounding environment. Zakrzewski’s method for determining the angle of directional hearing acuity (ADHA) was used. Measurements were made in a free field in an anechoic chamber for eight azimuths defined in a horizontal plane. The results indicate considerable differences in the ADHA values for individual signals, in particular for the frequency of 4000 Hz.