Effects of delayed auditory feedback on speech kinematics in fluent speakers.

The effects of delayed auditory feedback on behavioral responses and speech kinematics were investigated. Participants were 10 men (M age = 22.2 yr., SD = 3.7) and 10 women (M age = 20.5 yr., SD = 2.2). Participants were required to repeat shorter (6 syllables) and longer (11 syllables) non-words in a reading task. Speech errors, lip movement variability, and movement duration of labial trajectories under delayed feedback were compared to effects under gated speech feedback and a control or synchronous auditory feedback condition. Repeated-measures analysis indicated a lower percent of correct productions, higher variability, and slower duration of lip movements in the delayed feedback condition compared to the gated feedback and control conditions. Implications for auditory feedback of movement control in continuous speech and for theories of delayed auditory feedback that attribute a role to movements are discussed.