Generating 3-D auditory stimuli for the evaluation of spatial impression in musical instruments

Abstract

Spatial hearing plays an important, but not well understood, role in the perception of musical instruments and audio equipment. Psychophysical experiments are necessary to elucidate the processes which convey the spatial impression of sound sources. To this end, we propose a way to generate virtual stimuli for research on the spatial impression of musical instruments, specifically pianos. Our proposal, based on acoustical holography, takes a series of measurements over a dense grid and designs a virtual vibrating plate with the same directivity as the piano, as observed from the measuring grid. The number of active modes in the left-right and front-back directions of this virtual source can be controlled to reduce the radiation pattern complexity and generate a wide range of virtual stimuli. The resulting sound fields are rendered using binaural Ambisonics, using the position of the piano player as the spherical harmonic expansion center. The proposal was used in actual psychophysical experiments looking to shed light into the spatial impression of digital and acoustic pianos. The results show that the proposal does generate spatial sound signals which are consistently associated with different degrees of richness in the spatial impression.