Intelligibility of speech and its relationship to the speech spectrum—French and Steinberg revisited

Abstract

Knowledge of the relationship between the speech spectrum and intelligibility of speech is a key factor in being able to maximize intelligibility for the hearing‐impaired listener and for the normal listener under such adverse conditions as bandwidth attenuation or masking by noise. The present experiment was designed to allow the speech spectrum to pass, binaurally, to a normal listener, with an optimally flat response of the electroacoustic system. A real‐time programmable digital filter was then used to allow only certain bandwidths of the spectrum to be heard by the listener. The bandwidth locations were chosen to include the formants of the talker's voice. The experimental results were then compared to the classic results of French and Steinberg. It was observed that high‐pass and low‐pass filter tests, generally, agreed with French and Steinberg's observations; however, it was also found that bandpass filter tests do not agree since comparison to the older experimental results is inappropriate. From these new results, a revised analytical procedure for intelligibility versus the speech spectrum is being developed.