Vestibulocollic reflex(VCR) which stabilizes head position in space is essential for adequate motor performance, maintaining balance and posture. Vestibulocollic reflex evoked by acoustic stimulation was measured by the averaged surface myoelectric signal of the sternocleidomastoid muscles. The sound stimulation(0.1 msec, 95 dB, 5 Hz click) through headphone was given to the ears bilaterally and electromyography were recorded from surface electrode over the sternocleidomastoid muscles and averaged simultaneously.

The P1 potential latency was 11.33±0.97 msec, N1 19.67±2.64msec, P2 25.91±3.26msec, N2 31.38±3.39msec and P3 40.44±3.64msec. The P1N1 potential amplitude was 45.26±20.82μV and N1P2 potential amplitude was 26.42±16.34μV. The P1 and N1 potentials were present in all subject, but P2, N2 and P3 potentials were present in most but not all subject.