The effects of clear speech on crossmodal speech perception

Abstract

Six talkers were videotaped while they spoke a list of sentences twice: first while using conversational speech and then while using clear speech. The recorded stimuli were randomized (across talkers and type of utterances) and presented to three groups of subjects. Each group observed the stimuli under one of three experimental conditions: audio-only (A); visual-only (V); or, audio-visually (AV). For the two conditions in which the auditory signal was provided, a broadband noise was used to degrade the signal. The percent correct keyword recognition scores obtained from the subjects were used to determine the speech intelligibility of individual talkers. For each talker two speech intelligibility scores were obtained (in each sensory modality): one each for the tokens of conversational and clear speech. The results indicated that, in all sensory modalities, the talkers were more intelligible when they produced clear speech than when they used conversational speech.