Localization and externalization of speech through hearing aids with adaptive features

Abstract

Hearing aids with advanced digital signal processing features that analyze acoustic scenes can amplify wanted sounds (e.g., speech) while utilizing complex noise reduction features to attenuate unwanted sounds (e.g., noise). These adaptive features can be programmed to be more or less aggressive in order to prioritize listening comfort or speech detail. Importantly, these adaptive features may alter the interaural cues of relevant target talkers located in front of the listener, causing unwanted effects on spatial perception. Here, we explored these effects. Spondees were presented from 11 different loudspeakers (located between ±75° azimuth separated by 15°) in an anechoic chamber. Binaural recordings were obtained from the ear canals of a Bruel & Kjaer Head and Torso Simulator, which was fitted with Oticon More hearing aids. The recordings were then presented over headphones to listeners, who indicated the perceived direction and degree of externalization of the spondees. Several conditions were tested, which differed in the acoustics of the room (anechoic and simulated reverberation), the background (quiet and noise), and the hearing-aid coupling (unaided, open-fit, and occluded). Behavioral data will be compared to measured interaural cues in the corresponding binaural recordings.