Effects of signal processing on intelligibility of speech in noise for persons with sensorineural hearing loss.

A person with sensorineural hearing loss accompanied by recruitment has difficulty in understanding amplified speech, especially when speech is in the presence o competition. Two groups of subjects with sensorineural hearing loss with recruitment were tested at +6 and at O dB signal-to-noise (S/N) ratio at preferred levels for unprocessed speech and for speech processed through a two-band compression/equalization of circuit. In addition, unprocessed key word identification scores were compared to those from use of a hearing aid and of a one-band compression/equalization circuit. Processing a two-band compression/equalization circuit improved key word identification scores dramatically for both groups of subjects. The range of improvement for both groups was from 6 to 74%, mean 37.4%, for the S/N ratio of O dB. Subjects who achieved higher scores had high scores for unprocessed tests and had less recruitment present throughout the frequency range. Scores from one-band compression/equalization were compared to those from unprocessed scores; there were no significant differences in key word identification. Design characteristics and an excellent rationale for using two-band compression/equalization are generated by the data of this study.