ABSTRACT
This chapter aims to quantify the effects of audibility on speech recognition by hearing-impaired listeners using the speech intelligibility index. It provides a desensitization factor that can be used to account for the less-than-optimal use of the audible signal by some hearing-impaired listeners. The chapter discusses the factor to frequency and temporal resolution abilities of the listeners. The speech stimuli were filtered sentences, and the psychoacoustic stimuli comprised probe tones at 0.35, 1, 2, and 4 kHz, and narrowband continuous noise, notched noise, and gated noise makers. A central issue in amplification for hearing-impaired listeners is to match the acoustic signal to the residual auditory area so that as much of the speech signal is made audible to the listener as possible. C. V Pavlovic reported that speech intelligibility of hearing-impaired listeners was comparable to that of a normal control group when the stimuli were presented in the frequency region in which the hearing-impaired listeners had near-normal thresholds.
