Middle ear reflex activity in the startle reaction.

By means of extratympanic phonometry, the middle ear muscular reflex activity in the startle reaction was measured in a control series, in patients with otosclerosis and in patients with operation cavaties without a functioning tensor tympani muscle. In comparison with the stapedius reflex, the startle reflex was found to be much more variable regarding latency, amplitude, and configuration. It was characterized by pronounced fatigue and a high alertness dependence. The period of latency was about 60 msec. It was possible to elicit a distinct startle reflex in operation cavities without a functioning tensor tympani muscle, probably because of contraction of the Eustachian tube muscles.