Sound source localization using hearing aids with microphones placed behind-the-ear, in-the-canal, and in-the-pinna

Abstract

Abstract

Objective: The effect of different commercial hearing aids on the ability to resolve front-back confusions and on sound localization in the frontal horizontal and vertical plane was studied. Design: Commercial hearing aids with a microphone placed in-the-ear-canal (ITC), behind-the-ear (BTE), and in-the-pinna (ITP) were evaluated in the frontal and full horizontal plane, and in the frontal vertical plane. Study Sample: A group of 13 hearing-impaired subjects evaluated the hearing aids. Nine normal-hearing listeners were used as a reference group. Results and Conclusions: Differences in sound localization in the front-back dimension were found for different hearing aids. A large inter-subject variability was found during the front-back and elevation experiments. With ITP or ITC microphones, almost all natural spectral information was preserved. One of the BTE hearing aids, which is equipped with a directional microphone configuration, generated a sufficient amount of spectral cues to allow front-back discrimination. No significant effect of hearing aids on elevation performance in the frontal vertical plane was observed. Hearing-impaired subjects reached the same performance with and without the different hearing aids. In the unaided condition, a frequency-specific audibility correction was applied. Some of the hearing-impaired listeners reached normal hearing performance with this correction.

Sumario

Objetivo: Se estudio el efecto de diferentes auxiliares auditivos sobre la habilidad para resolver confusiones en dirección antero-posterior y en la localización del sonido en los planos fronto-horizontal y vertical. Diseño: Se analizaron auxiliares auditivos comerciales que tienen un micrófono localizado dentro del canal auditivo (ITC) y en la oreja (ITP) en el plano frontal, el horizontal y en el plano fronto-vertical. Muestra: Un grupo de 13 sujetos hipoacúsicos evaluaron los auxiliares auditivos. Nueve sujetos normoacúsicos sirvieron como grupo de referencia. Resultados y conclusiones: Se encontraron diferencias en la localización del sonido en la dimensión fronto-posterior con varios auxiliares auditivos. Se encontró una gran variabilidad inter-sujeto en los experimentos de dirección antero-posterior y de elevación. Uno de los auxiliares auditivos tipo curveta que está equipado con un micrófono direccional generó una cantidad suficiente de claves espectrales para poder discriminar en el plano antero-posterior. No se observó un efecto significativo de los auxiliares auditivos en el desempeño por elevación en el plano vertical. Los sujetos hipoacúsicos alcanzaron el mismo desempeño con y sin los diferentes auxiliares auditivos. Cuando los usaban se aplicó una corrección de audibilidad específica en frecuencia. Algunos de lo sujetos hipoacúsicos alcanzaron un desempeño de audición normal con esta corrección.

Key Words::

• Localization
• Hearing aids
• Front-back
• Elevation
• Horizontal
• Binaural

Acknowledgements

The authors would like to thank the subjects for their tremendous listening efforts, and Ann-Sophie Tilleckaerts for her assistance during the measurements. Also, we would like to thank William Noble and both reviewers including Fred Wightman for their extensive review which led to a significant improvement of the manuscript. This research was partly funded by GN ReSound and the FWO (research foundation Flanders) VIRTAK project G.0334.06N. Although the study was funded by GN ReSound, the presented data and its interpretation is that of ExpORL, K.U.Leuven. Preliminary data analyses were presented at the NAG-DAGA International Conference on Acoustics, Rotterdam, The Netherlands, March 23 to 26, 2009.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and the writing of the paper.