Inner speech captures the perception of external speech.

Talking silently to ourselves occupies much of our mental lives, yet the mechanisms underlying this experience remain unclear. The following experiments provide behavioral evidence that the auditory content of inner speech is provided by corollary discharge. Corollary discharge is the motor system's prediction of the sensory consequences of its actions. This prediction can bias perception of other sensations, pushing percepts to match with prediction. The two experiments below show this bias induced by inner speech, demonstrating that inner speech causes external sounds to be heard as similar to the imagined speech, and that this bias operates on subphonemic content.