For hearing aid noise reduction, babble is not just babble


  • Helen Connor Sørensen Global Audiology, GN ReSound A/S, Ballerup, Denmark
  • Charlotte T. Jespersen Global Audiology, GN ReSound A/S, Ballerup, Denmark


Most modern hearing aids provide single-microphone noise reduction without specifying how they work. The current study investigates how noise reduction is applied to babble noise in current premium hearing aids. Coupler gain measurements were performed in an acoustic test chamber. The signals used were standardized test signals, as well as babble noises compiled with different numbers of speakers (2, 4, 6, 8, and 10 speakers). The output of the hearing aid was measured with the noise reduction off and the strongest setting available. The gain reduction was calculated as the difference between the two settings. The results showed that, for an unmodulated test signal, the noise reduction algorithms applied quite different amounts of gain reduction across frequency. For the babble noise, some of the algorithms reduced gain very little, even for the 10-person babble. Other algorithms applied a graduated response, i.e., most gain reduction for 10-person babble, and the least amount of noise reduction for 2-person babble. Along with previous studies, this study highlights the need to have a standardized benchmarking procedure to define not only how noise reduction works in hearing aids but also which listening situations in which the noise reduction is active.


ANSI S3.42 (1992). American National Standard: Testing Hearing Aids with a Broad-Band Noise Signal. New York: American National Standards Institute.

Arehart, K., Souza, P., Kates, J., Lunner, T., and Pedersen, M.S. (2015). “Relationship among signal fidelity, hearing loss, and working memory for digital noise suppression,” Ear Hearing, 36, 505-516.

Bisgaard, N., Vlaming, M.S.M.G., and Dahlquist, M. (2010). “Standard audiograms for the IEC 60118-15 measurement procedure,” Trends Amplif., 14, 113-120.

Bentler, R. and Chiou, L.-K. (2009). “Digital noise reduction: An overview,” Trends Amplif., 10, 67-82.

Brons, I., Houben, R., and Dreschler, W.A. (2013). “Perceptual effects of noise reduction with respect to personal preference, speech intelligibility, and listening effort,” Ear. Hearing, 34, 29-41.

Brons, I., Houben, R., and Dreschler, W.A. (2014). “Effects of noise reduction on speech intelligibility, perceived listening effort, and personal preference in hearing-impaired listeners,” Trends Amplif., 18, 1-10.

Cox, R.M., Alexander, G.C., and Gilmore, C. (1987). “Development of the Connected Speech Test (CST),” Ear. Hearing, 8, 199S-126S.

Hoetink, A.E., Körössy, L., and Dreschler, W.A. (2009). “Classification of steady state gain reduction produced by amplitude modulation based noise reduction in digital hearing aids,” Int. J. Audiol., 48, 444-455.

Holube, I., Fredelake, S., and Vlamming, M. (2010). “Development and analysis of an international speech test signal (ISTS),” Int. J. Audiol., 49, 891-903.

Keidser, G., Dillon, H., Flax, M., Ching, T., and Brewer, C. (2011). “The NAL-NL2 prescription procedure,” Audiol. Res., 1S, e24.

Kochkin S. (2010). “MarkeTrak VIII: Consumer satisfaction with hearing aids is slowly increasing,” Hearing J., 63, 19-32.

Smeds, K., Bergman, N., Hertzman, S., and Nyman, T. (2010). “Noise reduction in modern hearing aids – long-term average gain measurements using speech,” in Proceedings of ISAAR 2009: Binaural Processing and Spatial Hearing. 2nd International Symposium on Auditory and Audiological Research. Elsinore, Denmark. Eds. J.M. Buchholz, T. Dau, J. Christensen-Dalsgaard, and T. Poulsen. ISBN: 87-990013-2-2 (The Danavox Jubilee Foundation, Copenhagen), pp. 289-298.




How to Cite

Sørensen, H. C., & Jespersen, C. T. (2015). For hearing aid noise reduction, babble is not just babble. Proceedings of the International Symposium on Auditory and Audiological Research, 5, 277–284. Retrieved from



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