A hearing test in which a vibrating tuning fork is placed on the mastoid process (see EAR). When the subject can no longer hear the ringing, it is placed beside the ear. Unaffected individuals can then hear the noise once more, but in people with conductive DEAFNESS, air conduction does not persist after bone conduction has ceased. It can help to distinguish between nerve (sensorineural) and conduction deafness.