AVHs occur in both normal and psychotic populations. DI model claims AVHs result from disrupted internalization of inner speech. RE model claims AVHs result from inner speech re-expanding into dialogue under stress and cognitive challenge. Both models derive from Vygotsky's theory of inner speech development. Normal inner speech is abbreviated relative to external speech. Normal inner speech undergoes semantic transformations. AVHs emerge when inner speech produces inappropriately expanded inner dialogue. Expanded dialogue causes subjects to perceive voices as alien. Models account for social-developmental evidence on AVHs. Models generate testable predictions for future research.