test is performed by placing a vibrating tuning fork against the patient's mastoid bone and ask the patient to tell you when the sound is no longer heard. Time this interval of bone conduction with a watch, noting the number of seconds. Quickly position the still vibrating tines 1-2 cm from the auditory canal, and again ask the patient to tell you when the sound is no longer heard. Continue timing the interval of sound due to air conduction heard by the patient. Compare the number of seconds sound is heard by bone conduction versus air conduction; air conducted sound should be heard twice as long as bone conducted sound (e.g., if bone-conducted sound is heard for 15 seconds, air-conducted sound should be heard for 30 seconds).