Hendrik Husstedt1, Wiebke Hilgerdenaar1,2, Marlitt Frenz1, Florian Denk 1, Jürgen Tchorz3, Simone Wollermann1
1German Institute of Hearing Aids, Lübeck, Germany
2Universität zu Lübeck, Lübeck, Germany
3Technische Hochschule Lübeck, Lübeck, Germany
Hearing aid users often report that short, impulse-like noise signals with high sound pressure levels such as slamming of a door or rattle of dishes are particularly annoying. Although the risk of presenting excessive sound levels is covered by the output limiter of hearing aids, features such as a general noise reduction or the automatic gain control are supposed to have no effect on those impulse signals. Therefore, some hearing aids provide an impulse (or transient) noise reduction that should reduce loud and short noise signals without impairing the desired signals, e.g., speech. In this work, we performed a technical evaluation of the impulse noise reduction of commercially available hearing aids of six different manufacturers. For this purpose, we made anechoic recordings of a set of impulse noises, presented them to the hearing aids attached to a head and torso simulator (KEMAR), and determined the C-weighted peak sound pressure levels at the output of the hearing aids. The hearing aids were fitted to a hearing loss of type N3 (according to IEC 60118-15), and the binaural coupling was activated. Various hearing aid configurations were considered where the general noise reduction, the automatic gain control, the output limiter, and the impulse noise reduction were activated or deactivated. Moreover, the impulse noises were presented in quiet, and within a speech pause of the international speech test signal (ISTS). These results give deep insights into the performance of the impulse noise reduction in hearing aids of multiple manufacturers, for different impulse noises, in quiet and within speech, and the interaction with other hearing aid features.