Middle Ear Transfer Function for Sound Conduction Study of Middle Ear Implants: A New Method.

Human temporal bone specimens are used in experiments to measure the sound transfer function of the middle ear. This standard method for the development of middle ear implants requires temporal bones that possess appropriate mechanical properties and structural stability and are free from pathological conditions. A laser Doppler vibrometer is commonly employed to measure the vibration of the stapes footplate. These experiments are typically conducted in the middle ear by leaving the inner ear intact, exposing the stapes footplate through the tympanic cavity, and directing the laser beam onto the footplate. However, previous studies have shown that the influence of inner ear impedance on the middle ear transfer function cannot be ignored, and any surgical manipulation may cause a change in inner ear pressure, resulting in instability in the middle ear transfer function. Therefore, this study aims to eliminate the influence of the inner ear and to establish a new experimental method in human temporal bone specimens that is more suitable for the study of sound conduction in middle ear implants. As a result, a range for middle ear transfer function was developed, which serves as a reference for assessing the conformity of temporal bone specimens to experimental standards, and the stability of this range was demonstrated under experimental conditions.