We use the 256K, 512K, and 1024K forks, but the 512K fork is the best screening fork. The normal response is midline. In general, the patient perceives the sound in the ear with the better BC or greater conductive component. With a pure conductive hearing loss, the sound will be perceived louder in the poorer hearing ear. With a pure sensorineural hearing loss, the sound will be perceived in the better hearing ear.
Ambiguity develops when one ear has both conductive and sensorineural hearing loss.
The ABR, a measure of electrical activity in the central auditory pathway similar to the EEG, is useful for establishing hearing thresholds in infants and difficult to test patients. A series of clicks are presented to the tested ear which elicit synchronous firing from high frequency auditory fibers.