Postural Control of the Vocal Tract Affects Auditory Speech Perception

Many researchers have proposed that sensorimotor information about the dynamic production of speech gestures can supplement the auditory perception of speech. Here we show that information about postural, nonspeech control of the vocal tract-such as breathing through the nose or mouth-also affects speech perception. Experimental participants breathed either through the nose or the mouth while identifying categories of speech sounds differing in nasal versus oral airflow. Participants showed an increased tendency to hear speech sounds as having nasal articulation when breathing through the nose, relative to when breathing through the mouth. These results suggest that postural information about the state of the vocal tract, like the motor configuration of the speech articulators while breathing, can modulate the perceptual processing of speech sounds.