Use of DSP Techniques to Enhance the Performance of Hearing Aids in Noise
The major complaint of individuals with hearing impairment, regardless of whether they wear hearing aids, is the reduced ability to understand speech in a noisy environment. The engineering challenge is to provide audibility of speech in order to overcome the hearing loss and simultaneously reduce background noise, thereby enhancing the signal-to-noise ratio (SNR) for the hearing-impaired person. Digital signal processing (DSP) holds significant promise of precise and accurate compensation for hearing loss. The hearing loss for speech intelligibility in noise is measured as the SNR required for the listener to maintain understanding of conversational speech in the presence of noise. Treatment for SNR loss, or the impairment of processing ability in the presence of background noise, is an area of great potential for DSP applications in hearing aids. Techniques to improve speech understanding in noise include binaurally integrated amplification, directional microphone technology, and digital noise reduction algorithms.