SPEAKING CLEARLY FOR THE HARD-OF-HEARING .4. FURTHER-STUDIES OF THE ROLE OF SPEAKING RATE

The contribution of reduced speaking rate to the intelligibility of '' clear'' speech (Picheny, Durlach, & Braida, 1985) was evaluated by adj usting the durations of speech segments (a) via nonuniform signal time -scaling, (b) by deleting and inserting pauses, and (c) by eliciting m aterials from a professional speaker at a wide range of speaking rates . Key words in clearly spoken nonsense sentences were substantially mo re intelligible than those spoken conversationally (15 points) when pr esented in quiet for listeners with sensorineural impairments and when presented in a noise background to listeners with normal hearing. Rep eated presentation of conversational materials also improved scores (6 points). However, degradations introduced by segment-by-segment time- scaling rendered this time-scaling technique problematic as a means of converting speaking styles. Scores for key words excised from these m aterials and presented in isolation generally exhibited the same trend s as in sentence contexts. Manipulation of pause structure reduced sco res both when additional pauses were introduced into conversational se ntences and when pauses were deleted from clear sentences. Key-word sc ores for materials produced by a professional talker were inversely co rrelated with speaking rate, but conversational rate scores did not ap proach those of clear speech for other talkers. In all experiments, li steners with normal hearing exposed to flat-spectrum background noise performed similarly to listeners with hearing loss.