Relative onset times of voicing and visible articulation are potential cues for lipreaders to recognize nasal/stop consonants. For bilabials, a phototransistor behind the teeth and an external microphone indicated mouth opening and voice onset, respectively. Average voice leads for ten adults were: /ma/, +66 msec; /ba/, −1 msec; /pa/, −8 msec (/ma‐ba/ boundary, +28 msec; /ba‐pa/ boundary, −18 msec). To test relative voice/mouth onset as aperceptualcue. we produced synthetic syllables: the face substitute was an oscilloscope pattern, forming a mouth shape for 250, 400. or 550 msec; the voice substitute was a vowel‐like buzz delivered through a hand‐held vibrator. Buzz accompanied mouth opening with lead times of +200 to −200 msec (40 msec steps), and ended simultaneously with mouth closure. Normal‐hearing observers labeled each combination “ma” “ba.” or “pa.” Practiced lipreaders with knowledge of the onset cue subdivided the continuum with boundaries at +82 msec (ma‐ba) and −87 msec (ba‐pa). Because articulatory and perceptual boundaries are not coincident, this combined‐mode cue appears insufficient unless performance can be improved through training.