Effects of vocal-motor interference on vocal pitch imitation.

The act of singing involves perceptual processing of pitch as well as vocal motor planning. One mechanism that may underlie this type of sensorimotor processing is auditory imagery. Prior research showed that less accurate singers, who report less vivid auditory imagery, engage in more preparatory subvocal movements than more accurate singers. The current research addressed the degree to which motor processing is causally involved in the preparatory auditory imagery that is associated with accurate vocal pitch matching. On each trial, participants were presented with a novel four-note target melody, then imagined the melody, and finally sang the melody aloud. During the auditory imagery period of the trials, participants either simply imagined the target melody (control) or imagined the melody while simultaneously engaged in one of the following secondary tasks: silently repeating the syllables /bɑtah/ (articulatory interference), continually droning a low quiet hum (phonatory interference), or exhaling continuously (phonatory suppression). Phonatory interference significantly disrupted vocal pitch matching relative to performance in the control task. Furthermore, the degree of phonatory disruption was related to participants' overall singing accuracy, such that less accurate singers were more disrupted by phonatory interference than more accurate singers. This suggests that less accurate singers rely on subvocalization to prepare for imitation, whereas more accurate singers may be able to rely on mental models of the actions needed to imitate pitch when subvocalization is prevented.