Finite-element simulation study of directional microphones

Authors

  • Mads Jakob Herring Jensen Widex A/S, Ny Vestergaardsvej 25, DK-3500 Værløse, Denmark

Abstract

In modern hearing aids, the performance of directional microphone systems is typically dependent on both the acoustics around the hearing aid and on the signal processing algorithms. The sound pressure at the microphone inlets depends on the position of the microphones in the hearing-aid shell, the shapes of the inlets, and on the precise position of the hearing aid on the head of the user. In the present work, the directional characteristics of a speci c hearing aid are modelled in free eld as well as on a head in free eld. The results are then compared to measured data on a manikin head. A nite-element model is used for simulating the acoustic eld around the hearing aid. The model calculates the sound pressure at the two microphones as a function of frequency and plane wave incidence angle. The two microphone signals then serve as the inputs to a directional signal processing algorithm. The model enables systematic studies of both the free- eld directional characteristics and the true (real world) characteristics of the hearing aid on a head. The model may be used in the early design phase of new hearing aids. Furthermore, it may be used for optimizing the performance of directional noise reduction algorithms for speci c hearing-aid geometries.

References

Fahy, F. J. (1995). “The Vibro-Acoustic Reciprocity Principle and Applications to Noise Control,” Acustica 81, 545-558.

Fels, J. (2008). From Children to Adults: How Binaural Cues and Ear Canal Impedances Grow, PhD thesis (Institute of Technical Acoustics, RWTH Aachen University, Logos Verlag Berlin, ISBN: 978-3-8325-1855-4).

Fels, J., Buthmann, P., and Vorländer, M. (2004). “Head-Related Transfer Functions of Children,” Acta Acustica united with Acustica 90, 918-927.

Additional Files

Published

2009-12-15

How to Cite

Jensen, M. J. H. (2009). Finite-element simulation study of directional microphones. Proceedings of the International Symposium on Auditory and Audiological Research, 2, 473–480. Retrieved from https://proceedings.isaar.eu/index.php/isaarproc/article/view/2009-48

Issue

Vol. 2 (2009): Binaural Processing and Spatial Hearing

Section

2009/4. Recent concepts in binaural cochlear-implant and hearing-aid processing

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