This letter reports a study designed to measure the benefits of voicing in the recognition of concurrent syllables. The target and distracter syllables were either voiced or whispered, producing four combinations of vocal contrast. Results show that listeners use voicing whenever it is present either to detect a target syllable or to reject a distracter. When the predictable effects of audibility were taken into account, limited evidence remained for the harmonic cancellation mechanism thought to make rejecting distracter syllables more effective than enhancing target syllables.