Multichannel adaptive noise reduction in digital hearing aids

We have developed a digital binaural hearing aid using Texas Instrument´s floating point TMS320C3X digital signal processing (DSP) chip. The device is referred to as the Digital Programmable Hearing Aid (DIPHA). It has the capability of being programmed to perform a variety of speech processing tasks and is in essence a digital hearing lens. It permits matching the processing strategy to an individual´s specific hearing loss. This paper deals with the adaptive noise reduction algorithm employed by DIPHA. Typically the audiologist/therapist selects a number of bandpass filters to design (in effect) a custom binaural equalizer for the hearing impaired subject and cascades the noise reduction algorithm with the equalizer. This paper explores the concept of performing the adaptive noise reduction in individual bands of the equalizer, a multichannel adaptive noise reduction strategy for the hearing impaired