A MEASUREMENT SYSTEM FOR EVALUATION OF TH E SOUND-TRANSMITTING PROPERTIES OF MIDDLE-EAR IMPLANTS

a measurement system was developed that permits objective comparisons of the sound conduction of middle ear implants. The im plants are fitt ed into a mechanical middle ear model which approximates the impedance s of the eardrum and the inner ear. A defined signal within the freque ncy range of 0-5 kHz is provided by a miniaturized loudspeaker at The input to the model and is measured by a probe microphone. Displacement of an artificial stapes footplate at the output of the model is measu red by a fiberoptic probe with a sensitivity of 5 nm. The transmission function is calculated as the quotient of the output and the input si gnal. This system can be used to evaluate the sound-transmitting prope rties of different middle ear implants excepting other influences, suc h as surgical techniques. This work details the measurement system and demonstrates basic influences on the sound-transmission of middle ear implants.