Preserving spatial perception in reverberant environments using direct-sound driven dynamic range compression

Abstract

Fast-acting hearing-aid compression typically distort the auditory cues involved in the spatial perception of sounds in rooms, due to the enhancement of low-level reverberant energy portions of the sound relative to the direct sound. The present study investigated the benefit of a novel direct-sound driven compression scheme that adaptively selects appropriate time constants to preserve the listener’s spatial impression. Specifically, fast-acting compression was maintained for time-frequency (T-F) units dominated by the direct sound while the compressor was linearized via longer time constants for T-F units dominated by reverberation. This novel compression scheme was evaluated with normal-hearing listeners who indicated their perceived location and distribution of virtualized speech in the horizontal plane. The results confirmed that both independent compression at each ear and linked compression across ears resulted in more diffuse and broader, sometimes internalized, sound images as well as image splits. In contrast, the novel linked direct-sound driven compressor provided the listeners with a similar spatial perception obtained with linear processing that served as a reference. Independent direct-sound driven compression created a sense of movement of the sound between the two ears, suggesting that preserving the interaural level differences via linked compression is advantageous with the proposed direct-driven compression scheme.