Vestibular evoked myogenic responses to amplitude modulated sounds.

Auditory steady state responses (ASSR) allow objective assessment of hearing thresholds. At high stimulation levels artifactual responses have been reported in subjects with severe to profound deafness. Relatively large amplitude 'steady state' responses to amplitude modulated tones were measured from the Sternocleidomastoid muscle at 500 Hz. Response thresholds were similar to those of vestibular evoked myogenic potentials and scaled with neck muscle tension. 'Steady-state' myogenic responses showed broad tuning to modulation frequency. Reduced amplitude responses were measured at the inion indicating volume conduction from the SCM. While dependant on neck tension, such responses are a potential source of artifacts when recording ASSR.