EFFECTS OF TEMPORAL SMEARING ON TEMPORAL RESOLUTION, FREQUENCY-SELECTIVITY, AND SPEECH-INTELLIGIBILITY

Envelopes of speech were smeared in 23 parallel frequency channels. Th e smeared speech was presented to normal-hearing listeners, and the ef fects of different smearing magnitudes on speech intelligibility were measured by obtaining speech recognition scores. It was demonstrated t heoretically and experimentally that the system consisting of the comp uter smearing and the auditory system had reduced temporal resolution but nearly normal frequency resolution. Speech intelligibility of the processed vowel-consonant nonsense syllables was tested for low- and h igh-pass filter conditions. The overall speech recognition scores as w ell as the recognition scores of the consonants grouped according to a rticulatory features were analyzed. The results indicated that smearin g with a narrow temporal window did not degrade speech. The larger equ ivalent rectangular durations (ERDs) of the resultant temporal window (RTW) of the combined system (temporal smearing plus auditory system) produced a small but significant reduction in speech intelligibility f or the low-pass filter condition. Scores for the RTWs>l6 ms were signi ficantly different from the score for the 7.7-ms RTW for the high-pass filter condition; but this effect was small and did not differ across articulatory features.