Auditory redundancy gains were assessed in two experiments using a simple reaction time task. In each trial an auditory stimulus was presented either to the left ear, to the right ear, or simultaneously to both ears. The physical difference between auditory stimuli presented to the two ears was systematically increased across experiments. No redundancy gains were observed when the stimuli were identical pure tones or pure tones of different frequencies (Exp. 1). A clear redundancy gain and evidence of coactivation was obtained, however, when one stimulus was a pure tone and the other was white noise (Exp. 2). Experiment 3 employed a 2-AFC localization task and provided evidence that dichotically presented pure tones of different frequencies are apparently integrated to a single percept whereas a pure tone and white noise are not fused. The results extend previous findings of redundancy gains and coactivation with visual and bimodal stimuli to the auditory modality. Furthermore, at least within this modality, the results indicate that redundancy gains do not emerge when redundant stimuli are integrated into a single percept.