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

Abstract

Fast-acting hearing-aid compression systems typically distort the auditory cues involved in the spatial perception of sounds in rooms by enhancing low-level reverberant energy portions of the sound relative to the direct sound. The present study investigated the benefit of a direct-sound driven compression system that adaptively selects appropriate time constants to preserve the listener's spatial impression. Specifically, fast-acting compression was maintained for time-frequency units dominated by the direct sound while the processing of the compressor was linearized for time-frequency units dominated by reverberation. This compression scheme was evaluated with normal-hearing listeners who indicated their perceived location and distribution of sound images in the horizontal plane for virtualized speech. The experimental results confirmed that both independent compression at each ear and linked compression across ears resulted in broader, sometimes internalized, sound images as well as image splits. In contrast, the linked direct-sound driven compression system provided the listeners with a spatial perception similar to that obtained with linear processing that served as the reference condition. The independent direct-sound driven compressor 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-sound driven compression scheme.

Sound Externalization: A Review of Recent Research

“…As a more multidimensional approach to evaluate spatial perception, Toole (1970) asked listeners for ratings of the direction and distance of externalized sources and for the percentage of the total sound that is located inside the head for internalized images. A related approach is to let listeners sketch sound source positions using a template that includes the head and some reference points in external space (e.g., Cubick et al., 2018 ; Hassager, May, et al., 2017 ; Hassager, Wiinberg, et al., 2017 ; Robinson & Xiang, 2013 ), although this approach has not been extended to include a quantification of the degree of externalization based on the sketches.…”

Context-dependent trading of binaural spatial cues in virtual reality

“…More specifically, factors such as microphone placement, disruption of pinna cues, and dynamic range compression haven been shown to contribute to difficulty localizing (e.g., Diedesch, 2016;Diedesch et al, 2018;Hassager et al, 2017). Hassager et al (2017) reported hearing aid processing can lead to auditory images that are broad, intracranial or split, which falls within the purview of the current study.…”

Modeling the effects of dynamic range compression on signals in noise

“…Of course, real hearing aids do not have access to the unmixed source signals, so a practical multisource compression system must perform source separation. Hassager et al (2017) used a single-microphone classification method to separate direct from reverberant signal components, helping to preserve spatial cues that can be distorted by DRC. May et al (2018) proposed a single-microphone separation system that applies fast-acting compression to speech components and slow-acting compression to noise components; listening experiments with an oracle separation algorithm improved both quality and intelligibility (Kowalewski et al, 2020).…”