Signal-Processing Strategy for Restoration of Cross-Channel Suppression in Hearing-Impaired Listeners

Abstract

Because frequency components interact nonlinearly with each other inside the cochlea, the loudness growth of tones is relatively simple in comparison to the loudness growth of complex sounds. The term suppression refers to a reduction in the response growth of one tone in the presence of a second tone. Suppression is a salient feature of normal cochlear processing and contributes to psychophysical masking. Suppression is evident in many measurements of cochlear function in subjects with normal hearing, including distortion-product otoacoustic emissions (DPOAEs). Suppression is also evident, to a lesser extent, in subjects with mild-to-moderate hearing loss. This paper describes a hearing-aid signal-processing strategy that aims to restore both loudness growth and two-tone suppression in hearing-impaired listeners. The prescription of gain for this strategy is based on measurements of loudness by a method known as categorical loudness scaling. The proposed signal-processing strategy reproduces measured DPOAE suppression tuning curves and generalizes to any number of frequency components. The restoration of both normal suppression and normal loudness has the potential to improve hearing-aid performance and user satisfaction.

Multi-tone suppression of distortion-product otoacoustic emissions in humans

“…Although DPOAE generation mechanisms may be more complex theoretically compared to SFOAEs, DPOAEs were favored for this study because (1) we have experience measuring DPOAE suppression in previous studies (e.g., Gorga et al, 2008;Gorga et al, 2011a,b;Gruhlke et al, 2012;Birkholz et al, 2012) and (2) the study was motivated by a recent paper by Rasetshwane et al (2014) describing a signal-processing algorithm inspired by DPOAE suppression data that assumes an additive-intensity model.…”

“…Rasetshwane et al (2014) used data from Gorga et al (2008) and Gorga et al (2011b) to develop a signalprocessing algorithm for hearing aids that aims to restore, among other things, normal suppression, which presumably would be beneficial to individuals with hearing loss because they lack normal cochlear suppression (Abdala and Fitzgerald, 2003;Gorga et al, 2003;Birkholz et al, 2012;Gruhlke et al, 2012). In order to generalize the suppressive effect of a single suppressor tone to the case when there are multiple frequency components, Rasetshwane et al (2014) assumed that suppressive effects were additive in terms of variables that represented the relative intensities of different frequency components. We adopted a similar approach in this study by defining a quantity based on Eq.…”

Influence of suppression on restoration of spectral loudness summation in listeners with hearing loss

“…Brief descriptions of the signal processing and gain prescription algorithms are provided below. Please see Rasetshwane et al (2014b) for a more detailed description of the SHA.…”

“…We previously described a hearing-aid signal-processing algorithm that mimics the effects of normal cochlear suppression, which we referred to as the suppression hearing aid (SHA) (Rasetshwane et al, 2014b). The suppressive influence of one frequency on another frequency in the SHA is based on measurements of distortion-product otoacoustic emission (DPOAE) suppression tuning curves in humans with NH (Gorga et al, 2011a).…”

Self-Fitting Algorithm for Digital Hearing Aid Based on Interactive Evolutionary Computation and Expert System

“…Furthermore, hearing rehabilitation is expected to face more severe challenges due to the ageing of the global population [2,3]. Currently, the use of hearing aids is one of the most effective means of hearing rehabilitation [4]. However, even in developed countries, only one in five people has hearing aids [5].…”