How directional microphones affect speech recognition, listening effort and localisation for listeners with moderate-to-severe hearing loss

Abstract

Objective: The purpose of this study was to evaluate the effects of directional microphone use on laboratory measures of sentence recognition, listening effort and localisation. An additional purpose of this study was to evaluate the effects of asymmetric directional microphone use on the same laboratory measures. Design: Three hearing aid conditions were evaluated: (1) bilateral omnidirectional microphones, (2) bilateral directional microphones and (3) asymmetric microphones (directional microphone for only one hearing aid). Sentence recognition performance was evaluated using a connected speech test. Listening effort was evaluated using a dual-task paradigm with a response time-based secondary task requiring word categorisation. Localisation was examined using a complex task requiring localisation and recall of speech originating from one of four loudspeakers in the horizontal plane (−60°, −45°, +45°, +60°). Study sample: Eighteen adults (M = 61.8 years) with symmetrical, moderate-to-severe hearing loss participated. Results: Performance on each task was analysed separately using a repeated measures analysis of variance. Results revealed directional benefits for sentence recognition and listening effort, but microphone setting did not affect localisation. Performance was equivalent with symmetric and asymmetric directional configurations. Conclusions: Bilateral and asymmetric directional microphone configurations equally improved sentence recognition and listening effort; neither affected localisation or recall.