Multiband compression and contrast-enhancing frequency shaping in hearing aids

A hearing-aid amplification scheme that uses a formant-tracking algorithm and time-varying filter to produce improved contrast enhancement between formants is presented. The combination of contrast-enhancing frequency shaping (CEFS) amplification and multiband compression in a single frequency-domain filterbank implementation is also studied. CEFS compensates for the broadened tuning curves and elevated thresholds of an impaired ear by adjusting the relative amplitudes of the formats without distorting the spectral envelope between the formats. The new multiband-CEFS (M-CEFS) algorithm utilizes a formant tracker to direct the gain-frequency response of a time-varying filter.