(PP1330) Localization with a Microphone and Receiver-in-the-Ear Hearing Aid Improves with Experience

Abstract: A microphone and a receiver-in-the-ear (M&RIE) module preserves users’ natural cues for spatial hearing compared to a traditional Receiver-in-the-ear (RIE) hearing aid with microphones placed behind the ear. This study investigated localization benefit with M&RIE over time. Ten hearing-impaired participants fitted with hearing aids combined with M&RIE receivers were followed. Localization performance was evaluated at fitting and repeated after 4 and 8 months of wear time. The results showed that users’ front-back localization with M&RIE improved significantly already after a 4-month adaptation period.

Summary: 

Introduction and objective
Spectral cues provided by the torso, head and pinna help in localizing sound. Today’s most popular hearing aid style, the Receiver-in-the-Ear (RIE), picks up sound via microphones located on the device worn behind the ear, which eliminates the natural way of hearing and thereby spatial hearing cues.

A M&RIE module preserves individual spectral cues by placing a microphone in the ear canal (Groth, 2020). This microphone placement has been shown to improve localization as measured by a significant reduction in front-back confusions relative to traditional RIE microphone placement (Jespersen et al., 2020).

The purpose of this study was to test whether localization benefit with M&RIE was affected by experience in wearing the hearing aid over time.

Methods
Ten adults with bilateral mild-to-moderate sloping sensorineural hearing loss participated in the study. Participants were fitted with hearing aids, M&RIE receivers and domes appropriate for their hearing loss. The participants were asked to use the hearing aids for a period of two years. Their localization performance was evaluated over 3 visits so far: at the fitting, after 4 months and again after 8 months usage of the hearing aids fitted with M&RIE receivers.

At the first visit, the participants performed the localization test for three different conditions: unaided, with the traditional RIE receivers (for benchmark testing) and with the M&RIE receivers. The test order of the conditions was counterbalanced across participants. The participants repeated the localization test after a 4-month and 8-month adaptation period using the hearing aids fitted with the M&RIE receivers.

Participants were seated in the middle of a twelve-loudspeaker setup separated by 30°. 250ms white noise bursts were played randomly from one of the loudspeakers. Participants responded by stating from which loudspeaker they perceived the stimulus was played. This procedure was repeated 5 times for each angle.

The average front-back error was calculated for each test condition. Statistical comparisons were performed between the M&RIE and the traditional RIE receiver at visit 1 prior to any adaptation to the M&RIE receiver as well as between the M&RIE at visit 1, and M&RIE after 4 months and 8 months of adaptation to the M&RIE receiver. The Tukey Honest Significant Difference statistical criterion was used for the comparisons.

Results & Conclusions
On average, the participants made fewer front-back localization errors with M&RIE than with the RIE receivers.

The participants demonstrated a significant improvement in performance on the front-back localization task already after 4 months of wear time with the M&RIE receivers (p< 0.01) compared to M&RIE at the fitting. The average front-back error decreased even further after using M&RIE for 8 months despite this decrease not being significant.

These results support that placing the microphones in and behind the ear helps the user localize and that this benefit in localization even improves with use time.

References
1. Groth J. An innovative RIE with microphone in the ear lets users “hear with their own ears”. ReSound white paper. 2020.

2. Jespersen C, Kirkwood B, Schindwolf I. M&RIE receiver preferred for sound quality and localization. ReSound white paper. 2020.