Gerald A. Studebaker
Robert L. Sherbecoe
Memphis Speech and Univ. of Memphis Hear. Center, 807 Jefferson Ave., Memphis, TN 38105
One finding of the early investigators at the Bell Telephone Laboratories was that the articulation index (AI) decreased when speech was amplified above normal conversational levels (French and Steinberg, 1947; Fletcher and Galt, 1950). Recent efforts to predict the performance of hearing-impaired subjects using hearing aids under real world conditions has produced a renewed interest in this phenomenon. A study will be described that attempts to quantify the effects of higher than normal speech and noise levels. Data for normal-hearing subjects revealed that raising the speech level from 65 to 100 dB SPL reduced the AI by about 0.003 units per dB and that this slope remained fairly constant for S/N ratios between -2 and +19 dB. Data on hearing-impaired subjects are currently being collected. Results for both subject groups will be compared with those obtained by Fletcher and his colleagues.