Pre-implant evaluation of speech and hearing

This paper describes an approach taken to predict, in advance of invasive surgery, whether a permanent cochlear prosthesis will serve as an aid to hearing in postlingually deaf adults. Nine subjects were implanted transtympanically with a temporary single-channel round window electrode. Over the course of one week a number of tests were conducted, including (1) the measurement of current thresholds over a range of frequencies for sine, square and biphasic pulse waveforms and minimum detectable gap between a pair of short bursts; (2) the discrimination of elementary speech features of live voice such as interruption, intonation, and stress placement; (3) the recognition of consonants, and (4) speech tracking. Eight subjects were able to appreciate changes in loudness, pitch, duration and temporal gap for frequencies below 1 kHz. All showed significant improvements over listening with high-power hearing aids in discriminating a variety of changes in elementary speech features. It was found that the recognition of consonants and speech tracking was heavily dependent on lipreading.