In an attempt to distinguish normal from abnormal eustachian tube function, two groups of adults with nonintact tympanic membranes were tested. Six subjects had traumatic perforations of the tympanic membrane and a negative otologic histroy while five subjects had perforations as a sequela of otitis media. The subjects were tested with two methods: the middle ear inflation-deflation technique and a newly introduced forced-response technique. The comparison of the two groups revealed marked differences between normal subjects and patients with middle ear disease in active tubal dilation mechanisms and biomechanics of the eustachian tube. The forced-response test appeared to be a better method to determine the degree of actual tubal function.