Electrophysiological evidence for a general auditory prediction deficit in adults who stutter.

We previously found that stuttering individuals do not show the typical auditory modulation observed during speech planning in nonstuttering individuals. In this follow-up study, we further elucidate this difference by investigating whether stuttering speakers' atypical auditory modulation is observed only when sensory predictions are based on movement planning or also when predictable auditory input is not a consequence of one's own actions. We recorded 10 stuttering and 10 nonstuttering adults' auditory evoked potentials in response to random probe tones delivered while anticipating either speaking aloud or hearing one's own speech played back and in a control condition without auditory input (besides probe tones). N1 amplitude of nonstuttering speakers was reduced prior to both speaking and hearing versus the control condition. Stuttering speakers, however, showed no N1 amplitude reduction in either the speaking or hearing condition as compared with control. Thus, findings suggest that stuttering speakers have general auditory prediction difficulties.