Signal processing to improve intelligibility in the presence of noice for persons with a ski-slope hearing impairment

A two-band compression system was designed to improve the intelligibility of speech in noise for persons suffering from sensori-neural hearing impairment. Experiments were carried out at 0 and +6 dB signal-to-noise (S/N) ratio with expansion below compression threshold. Six subjects had mean discrimination scores at S/N of 6 dB of 46, 77, and 87 percent with unprocessed speech (present heating aid), compression but linear below threshold, and compression with expansion below threshold, respectively. At the 0 dB S/N test score means were 21, 61 and 69 percent, respectively.