Voice fundamental frequency as an auditory supplement to the speechreading of sentences

Recognition of words in conversational sentences of known topic was measured in nine normally hearing subjects by speechreading alone and by speechreading supplemented with auditory presentation of the output of an electroglottograph. Mean word recognition probability rose from 30% to 77% with the addition of the acoustic signal. When this signal was filtered to remove possible high-frequency spectral cues, the supplemented score fell, but only by a marginally significant 7 percentage points, supporting the conclusion that voice fundamental frequency was the principal source of enhancement. Enhancement occurred for all subjects, regardless of speechreading competence.