The influence of bistable auditory feedback on speech motor control.

The precision of speech production is strongly influenced by the auditory feedback of our voice. Studies have demonstrated that when speakers receive perturbed auditory feedback, they spontaneously change their articulation to reduce the difference between the intended sound and what was heard. For controlling the accuracy of vowel and consonant production, this corrective behavior reflects the intended sound's category represented in the mind. This in turn suggests that sounds that are not represented as a category would be controlled differently. The current study investigated the effect of linguistic status on controlling the production of a sound. Participants used an apparatus to produce a bistable sound, which could be heard either as a vowel or an acoustic buzz depending on the instructions. During the production of the target sound, their auditory feedback was perturbed and the change in acoustics in response to the perturbation was measured. The results showed that the group producing a linguistic target exhibited an error-reducing behavior similar to what was reported in natural vowel production, whereas the group producing a non-linguistic acoustic target exhibited an error-amplifying behavior, even when the majority in this group had noticed the perturbation and consciously tried to counteract it. Our findings indicate that access to a stable representation differentiates the perceptual organization of auditory feedback, and consequently changes how the production of the sound is controlled.