An Acoustical Assessment of the Music Memory in Commercially Available Hearing Aids

Abstract

Hearing aids amplify speech-input signals using nonlinear amplification (i.e., wide dynamic range compression). When WDRC is used to process a music-input signal, listener’s report a negative aided listening experience. To circumvent this negative experience, hearing aids allow for music-input stimuli to be processed using a modified frequency-gain response, known as a memory or program. The music memory, in general, processes the input signal using a linear-like frequency-gain response, elevated output, or both. Increasing gain and output, we conjecture, has the potential to place the wearer at-risk (i.e., ≥85 Leq dBA) for Hearing-aid-induced hearing loss (HAIHL). We assessed the potential of this risk in two experiments. In Experiment I, 2-cc coupler gain was determined in three commercially available receiver-in-the ear/receiver-in-the-canal (RITE/RIC) hearing aids. Coupler gain responses were determined for a composite signal presented at 65 and 100 dB SPL for the WDRC memory and music memory, and for different degrees of occlusion. Results from this experiment were reported qualitatively. In Experiment II, the same three devices were fit on an acoustical manikin. Recordings of 10 musical passages were obtained for the same two memories, adjusted for the degree of occlusion at three presentation levels (i.e., 85-, 94-, and 103-dB SPL). Analyses of the recordings revealed that two devices programed in the music mode exceeded the at-risk threshold at presentation levels of 94- and 103-dB SPL. In addition, the same two devices programmed in WDRC exceeded the at-risk threshold at a presentation level of 103-dB SPL. Implications and future directions are discussed.