Observation of the vibration of the human ear drum using ultrasonic pulse doppler method has previously been reported elsewhere at our department. The present study includes, besides the human study, observetion of the guinea pig ear drum vibration under general anaesthesia and controlled respiration with tracheostomy. We were able to detect fine vibration of both the human and the guinea pig ear drum being responded to various sound stimuli by using the same ultrasonic pulse doppler apparatus with a fine probe, 1mm in diameter. We would like to emphasize the advantage of this method applying to the audiological investigation.
