Acoustic responses of the human middle ear

Measurements on human cadaver ears are reported that describe sound transmi ssion through the middle ear. Four response variables were measured with ac oustic stimulation at the tympanic membrane: stapes velocity, middle-ear ca vity sound pressure, acoustic impedance at the tympanic membrane and acoust ic impedance of the middle-ear cavity. Measurements of stapes velocity at d ifferent locations on the stapes suggest that stapes motion is predominantl y 'piston-like', for frequencies up to at least 2000 Hz. The measurements a re generally consistent with constraints of existing models. The measuremen ts are used (1) to show how the cavity pressure and the impedance at the ty mpanic membrane are related, (2) to develop a measurement-based middle-ear cavity model, which shows that the middle-ear cavity has only small effects on the motion of the tympanic membrane and stapes in the normal earl altho ugh it may play a more prominent role in pathological ears, and (3) to show that inter-ear variations in the impedance at the tympanic membrane and th e stapes velocity are not well correlated. (C) 2000 Elsevier Science B.V. A ll rights reserved.