The effect of a linked bilateral noise reduction processing on speech in noise performance

Authors

  • Jorge Meija National Acoustic Laboratories, Sydney, Australia; The Hearing Cooperative Research Centre, The University of Melbourne, Australia
  • Gitte Keidser National Acoustic Laboratories, Sydney, Australia; The Hearing Cooperative Research Centre, The University of Melbourne, Australia
  • Harvey Dillon National Acoustic Laboratories, Sydney, Australia; The Hearing Cooperative Research Centre, The University of Melbourne, Australia
  • Cong-Van Nguyen National Acoustic Laboratories, Sydney, Australia; The Hearing Cooperative Research Centre, The University of Melbourne, Australia
  • Earl Johnson The USA Department of Veterans Affairs, East Tennessee State University

Abstract

Directional processing already provides tangible noise reduction benefits in hearing aids but further improvement is needed for hearing-impaired listeners to communicate as effectively as normal-hearing listeners in noisy environments. The objective of this study was to investigate if a binaurally linked beamformer could further improve the signal-to-noise ratio (SNR). Speech reception thresholds (SRT) and spatial perception were compared for bilaterally fitted cardioid microphones and two binaurally linked beamformer processing conditions; 1) a single audio stream output to the two ears, and 2) two audio stream outputs which preserved spatial cues. 10 normal-hearing and 22 hearing-impaired listeners were recruited for this study. The strategies were implemented on a real-time PC processing platform, wired to a pair of behind-the-ear devices via a sound interface. A speech-in-noise test was administered using the Bamford-Kowal-Bench (BKB) sentences targeting the SNR for which 75% correct keywords were identified in spatially separated multi-talker babble noise and room reverberation. The SNR level at which the listeners acquired 95% intelligibility from continues speech discourse material, using a male and a female talker, was also obtained. Sound amplification was provided according to NAL-NL2. Both beamformer conditions improved the SRTs relative to the conventional cardioids, but by a greater degree for the hearing-impaired listeners, and more convincingly at the higher SRTs.

References

Baptise, J. MAJ., (2004). “Adaptive noise reduction algorithms for speech intelligibility improvement in dual microphones hearing aids” Katholieke Universiteit Leuven, Belgium.

Bench, R. J., Doyle, J., Daly, N., Lind, C. (1979). “The BKB/A Speech-reading (lip- reading) test” Victoria: La Trobe University.

Blauert, J., (1997). “Spatial hearing-The psychophysics of human sound localisation”. The MIT Press, England.

Blauert, J., (2005). Communication acoustics, Springer-Verlag, The Netherlands. Brandstein, M., and Ward, D., (2001). Microphone arrays - Signal processing techniques and applications, Springer-Verlag, Germany.

Dillon, H. (2010). “Mild hearing loss is serious business” International Hearing Aid Research Conference, August 11-15, Lake

Kates, J. M., (2008). Digital hearing aids, Plural Publishing, Inc, CA USA.

Keidser, G. (1995). “Long-term spectra of a range of real-life noisy environments” Aust. J. Audiol., 17, 39-46.

Keidser, G., Ching, T., Dillon, H., Agung, K., Brew, C., Brewer, S., Fisher, M., Foster, L., Grant, F., and Storey, L. (2002). “The National Acoustic Laboratories’ (NAL) CDs of Speech and Noise for Hearing Aid Evaluation: Normative Data and Potential Applications”. Austr. & N.Z. J. Audiol. 24,16-35.

Keidser, G., Dillon, H., Flax, M., Ching, T., and Brewer, S. (2011). “The NAL-NL2 prescription procedure” Audiology Research 1:e24: 88-90.

Markides, A., (1997). Binaural hearing aids, Academic Press.

Mejia., J., Dillon, H., and Carlile, S. (2006) ”A method and system for enhancing the intelligibility of sounds” WO/2007/137364.

Mejia, J., and Dillon, H., (2010). “A system and method for producing a directional output signal” WIPO Patent Application WO/2010/051606

Pearsons, K. S., Bennett, R. L., and Fidell, S. (1977). “Speech levels in various noise environments” Washington, D.C., U.S. Environmental Protection Agency

Powers, T. A., and Hamacher, V., (2002). “A Three-microphone instrument is designed to extend benefits of directionality” The Hearing Journal, 55. No.10. October.

Soede, W., (1990) Improvement of speech intelligibility in noise, N.K.B. Offset bv, Bleiswijk., The Netherlands.

Additional Files

Published

2011-12-15

How to Cite

Meija, J., Keidser, G., Dillon, H., Nguyen, C.-V., & Johnson, E. (2011). The effect of a linked bilateral noise reduction processing on speech in noise performance. Proceedings of the International Symposium on Auditory and Audiological Research, 3, 401–408. Retrieved from https://proceedings.isaar.eu/index.php/isaarproc/article/view/2011-46

Issue

Section

2011/4. Recent concepts in hearing-instrument processing and fitting