On the representation of speaker information in human voices : an adaptation approach Apart from being carriers of speech human voices contain a wealth of social signals for instance about a speaker’s gender identity or age to name but a few. The present thesis is concerned with the way adaptation modifies the perception of gender and identity information from voices. Adaptation is a mechanism by which neural responses decrease after continuous or repetitive stimulation. It is revealed by transient perceptual aftereffects indicating contrastive coding of simple and complex stimulus properties. The three studies reported here investigate unimodal and crossmodal auditory voice aftereffects of adaptation to unfamiliar and personally familiar speakers. Specifically study I (Exp. 1) shows that adaptation to unfamiliar voices of female or male speakers biases the perception of voice gender away from the adapting gender: test voices as created by auditory morphing between male and female voices are perceived as more male following adaptation to female voices and vice versa. The voice gender aftereffect (VGAE) survived at least a few minutes and suggests the existence of voice detectors tuned to female and male voice quality. The absence of voice aftereffects following adaptation to names (Exp. 2) faces (Exp. 3) or sinusoidal tones matched to F0 of adaptor voices (Exp. 4) further suggests that the VGAE is due to habituation of high level auditory representations.