The production of emotional prosody in varying severities of apraxia of speech

By S.M. Van Putten, J.P. Walker

One mild subject with apraxia of speech (AOS), one moderate AOS subject and one control subject were asked to produce utterances with different emotional intent in two different experiments. One experiment elicited sentences with emotional intent through a repetition task, and the other through a reading task. Acoustic analyses of the sentences produced suggest that neither the mild nor moderate AOS subjects were able to produce acoustic characteristics in their voice to distinguish between the different emotions. The control subject was able to use variations in fundamental frequency (FO), duration and intensity to express happy and sad emotion. The sentences produced in the first two experiments were played for naïve listeners in two additional experiments. Naïve listeners were asked to judge the emotional intent of the sentences using acoustic cues only. Naïve listeners were able to identify the emotional differences of the control speaker but could not distinguish between the emotional utterances of the mild or moderate AOS speakers. Comparisons between each AOS subject’s elicited and spontaneous sentences indicated that the moderate AOS subject was able to produce some acoustic variations to signal emotion, similar to normal speakers. These findings suggest that the AOS subjects may convey emotion non-verbally.