Click picture for film

Estimation of middle-ear parameters using vibration otoacoustic emissions

Mechanical parameters of the middle ear are estimated from  forward and reverse transfer functions as measured at the umbo. The forward transfer function derives from the velocity of the umbo in response to sound pressure in the ear canal. The reverse transfer function derives from otoacoustic emissions measured as umbo velocity and as sound pressure. In effect, for the reverse transfer function, the stimulus source derives from the otoacoustic emissions originating in the cochlea driving the middle ear in reverse. The umbo velocity emissions were measured with a custom-built laserinterferometer (Dalhoff et al., 2007) with a displacement sensitivity of a fraction of a nanometer. Commercially available devices still do not have the required sensitivity for measuring umbo vibration emissions in humans. The concept of the parameter estimation procedure is outlined in the film and the details are given in  Dalhoff et al. (2011).
Power point presentation and film by A.W. Gummer.