The gammachirp auditory filter and its application to speech perception

Abstract

We review the gammachirp (GC) auditory filter and its use in speech perception research. The GC was originally developed to explain the asymmetric, auditory filter shapes derived in notchednoise (NN) masking studies, and the strongly compressive input-output function observed in the mammalian cochlea. This compressive GC was fitted to a very large collection of notched-noise (NN) masking thresholds measured with a wide range of stimulus levels and center frequencies. The fit showed how the GC auditory filter could explain NN masking throughout the domain of human hearing with a relatively small number of parameters, only one of which was level dependent. Subsequently, a dynamic, compressive GC filterbank (dcGC-FB) was developed to simulate timedomain cochlear processing. This dcGC-FB has been used to cancel the peripheral compression of normal hearing and thereby simulate the most common forms of hearing loss. This simulator allows normal hearing listeners to experience the difficulties of hearing impaired listeners. It has been used in training courses for speech-language-hearing therapists and psychoacoustic experiments. The dcGC-FB has also been used for modeling speaker size perception and predicting speech intelligibility with GEDI (the gammachirp envelope distortion index).

Hearing impairment simulator based on auditory excitation pattern playback: WHIS

“…The background of cGC developed from the original gammachirp was reviewed by [15]. The absolute frequency response of a cGC [23], |G CC (f )|, can be formulated as follows: Here When the peak frequency of a pGC is f p1 and the sound pressure level at the pGC output is estimated as P gcp on a dB scale, the center frequency of HP-AF, the center frequency of HP-AF, f r2 , is associated with f p1 to introduce the level dependency of a cGC.…”

“…For example, HeLPS v2 [12] is commercially available and includes the simulation of loudness recruitment. We also developed another type of HL simulator [13]- [15], which is referred to as the Wakayama-University Hearing Impairment Simulator (WHIS), which is based on a dynamic compressive gammachirp filterbank (GCFB) [16]. The gammachirp filter in GCFB is a time-domain filter, unlike the roex filter, that accounts for the NN masking thresholds fairly well [17], [18].…”

Hearing Impairment Simulator Based on Auditory Excitation Pattern Playback: WHIS

“…The background of cGC developed from the original gammachirp was reviewed by [15]. The absolute frequency response of a cGC [23], |G CC (f )|, can be formulated as follows:…”

“…For example, HeLPS v2 [12] is a commercially available simulator that includes the simulation of loudness recruitment. We have also developed another type of HL simulator [13], [14], [15], which is referred to as the Wakayama-University Hearing Impairment Simulator (WHIS), which is based on a dynamic compressive gammachirp filterbank (GCFB) [16]. The gammachirp filter used in the GCFB is a time-domain filter, unlike the roex filter, that accounts for the NN masking thresholds fairly well [17], [18].…”

“…The value for an individual HI listener can be somewhat in the middle and frequency dependent. The parameter α is referred to as ''compression health'' as in the previous WHIS [15] although the definition and value are slightly different.…”