Most modern hearing-aids include different types of speech enhancement algorithms. Yet, decreased speech intelligibility in background noise is a common complaint of most hearing impaired even when speech enhancements algorithms are functional. Generally, the hearing-aid industry chose those algorithms that were proven to be most adequate to normal hearing subjects. However, it is not clear that an algorithm that is beneficial to normal hearing will increase the intelligibility of the hearing impaired as well, and vice-versa.
We have recently developed a single-channel speech enhancement technique that is based on an ear model comprising outer-hair cell functionality. The algorithm was evaluated in systematic speech intelligibility test of Hebrew words. Hearing impaired subjects, who used either a hearing –aid or a cochlear implant, demonstrated a significant improvement in their performance with the algorithm. On the other hand, normal hearing subjects demonstrated no improvement in their performance on the same task. We, therefore, suggest that speech enhancement algorithms for the hearing-impaired should be different from those that are beneficial to normal hearing subjects.