FIRST RESULTS OF ANALYSIS OF SOUND-TRANSM ISSION THROUGH THE RECONSTRUCTED MIDDLE-EAR WITH AN INNER-EAR HYDROPHONE

The acoustic result following reconstruction of the middle ear is ofte n dissapointing and unpredictable. Apart from biologic factors, this i s due to insufficient knowledge of the mechanism of sound transmission through the operated middle ear. Therefore, temporal bone experiments with simulated middle ear operations were set up to investigate the s ound transmission following different surgical procedures, different p rosthesis' designs, materials, etc. We developed a tiny hydrophone whi ch has a frequency range from 100 Hz to 10 kHz in order to measure the sound pressure in the cochlear fluid. By comparing the sound pressure in the inner ear with the sound pressure at the drum membrane, we wer e able to analyze the transfer function of the manipulated middle ear. First results with different reconstruction techniques, prosthesis' d esigns and attachments demonstrated the usefulness of this measuring t echnique for the development of acoustically better middle ear reconst ructions.