Effects of opening and resealing the cochlea on the mechanical response in the isolated temporal bone preparation.

The isolated temporal bone preparation has been used previously for studying the micromechanical behaviour of the cochlea. Mechanical tuning curves have been obtained from several cells and structures within the hearing organ. In order to obtain access to the apical turns the bony shell of the cochlea has to be opened. To study how the opening affects the mechanical response of the cochlea, experiments were performed in which the cochlea was opened and then sealed with a glass window. Responses were measured from the same identified cells in the opened and in the sealed cochlea. The opening of the cochlea reduced the vibration amplitude mainly at frequencies below 300 Hz. Below the mechanical resonance frequency the slope of the tuning curve became steeper. The shape was not affected appreciably above the resonance frequency. The relative vibration amplitude of different cells remained unchanged by opening and closing the cochlea.