FEATURES OF HEAD-RELATED TRANSFER FUNCTIONS DEFINING PERCEPTION OF MOVEMENT DIRECTION OF SOUND IMAGES IN VERTICAL MEDIAN PLANE

Simulation of sound movement is essential component of the works on creation of virtual acoustic space reality. Virtual auditory space techniques are necessary not only for the basic researches in the field of spatial hearing, but also for solving of many applied problems such as professional training of operators and medical rehabilitation of patients with hearing disorders. The problem of simulation of vertical sound movement on the basis of nonindividual head-related transfer functions is discussed in present report. Results of determination of the vertical movement direction (upward or downward) and the features of dynamic spectra of moving stimuli are compared. An attempt to develop the criteria for increase of the effectiveness of localization model using the nonindividualized head-related transfer functions is made. The obtained results suggest that the virtual signal features improving vertical localization are the regular shift of the first spectral notch and the gradual change of the signal amplitude. Modern spatial hearing studies usually based on the virtual auditory space technique, using socalled head-related transfer functions [1, 2]. Head-related transfer functions result from transformation of broadband sounds arriving to tympanic membrane from the free field. This transformation is