A trial of designing phoneme-enhancing and noise-suppressing directive hearing aid with the aim of auditory support for presbyacusic listeners

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We propose an adaptive digital filter which enhances transition of formants and band noise in consonants, so as to improve the articulation scores. The details are presented below.First, for enhancement of the formant transition of consonants, we beforehand generated band-pass filters whose characteristics of frequency match the human auditory filters. Sound signals were encoded by the sampling frequency and interval which were fit for acoustic features of consonants. Spectrum loci was estimated by selective linear predictive coding in order to select the band-pass filters which cover the band width of the local peaks of spectrum. The articulation test to enhanced consonants was carried out, which became evident that the editted consonants which have enhanced formant peaks improved the articulation.Second, a new algorithm was proposed to detect the consonants which have band noise as an acoustic feature, such as a fricative sound. Sound signals were separated into four band-pass filters, from which each amplitudes were calculated as acoustic cues for the detection. As a result, the fricative consonants were detected with three trigger outputs from the band-pass filters.