ABSTRACT
BACKGROUND: The tensor tympani muscle is the largest muscle within the middle ear. Its voluntary contraction is a very unusual event. Only a few papers have documented its audiometric effects. OBJECTIVE: To report an unusual case of voluntary tensor tympani muscle contraction and describe its audiometric effects. CASE REPORT: A 27-year-old man, who presented complaining of voluntarily evoked bilateral tinnitus, was found to be able to voluntarily contract the tensor tympani muscle in both ears simultaneously. Audiograms were performed under conditions of rest and maximal contraction of the tensor tympani muscle. The most remarkable effects were conductive hearing loss at lower frequencies and an increase in middle-ear impedance. CONCLUSION: The importance of the tensor tympani muscle in middle-ear physiology remains unclear. It has been related to the attenuation of sounds produced during the mastication process. Voluntary control over the tensor tympani muscle is an extremely rare event. However, an understanding of the potential audiometric effects of its contraction could aid the diagnosis of hearing disorders.