DESCRIPTION: The probe, to be designed for insertion in the external ear canal, would consist of two-single mode fibers, conducting light from a laser, a bundle of glass fibers carrying the interference image from a semi-transparent screen to the photodiode array, a pressurizer tube, a clear channel for acoustic stimulation and lenses to focus the light reflected from the tympanic membrane upon the semi-transparent screen, creating the interference image in conjunction with the reference beam.