Ocular and cervical vestibular evoked myogenic potentials elicited by air-conducted, low-frequency sound.

BACKGROUND Sound is not only detected by the cochlea, but also, at high intensities, by the vestibular system. Acoustic activation of the vestibular system can manifest itself in vestibular evoked myogenic potentials (VEMPs). In a clinical setting, VEMPs are usually evoked with rather high-frequency sound (500 Hz and higher), despite the fact that only a fraction of saccular and utricular hair cells in the striolar region is available for high-frequency stimulation. OBJECTIVE As a growing proportion of the population complains about low-frequency environmental noise, including reports on vestibular symptoms, the activation of the vestibular system by low-frequency sound deserves better understanding. METHODS We recorded growth functions of oVEMPs and cVEMPs evoked with air-conducted sound at 120 Hz and below. We estimated VEMP thresholds and tested whether phase changes of the stimulus carrier result in changes of VEMP amplitude and latency. RESULTS The VEMP response of the otholith organs to low-frequency sound is uniform and not tuned when corrected for middle ear attenuation by A-weighting the stimulus level. Different stimulus carrier phases result in phase-correlated changes of cVEMP latencies and amplitudes. CONCLUSIONS VEMPs can be evoked with rather low-frequency sound, but high thresholds suggest that they are unlikely to be triggered by environmental sounds.