This involves the delivery of pure sound frequencies by both air and bone conduction from 125 to 8000 hertz (cycles per second) at intensities from 0 to 110 decibels (dB). The threshold for sound perception is recorded and charted on a graph. It is possible to differentiate conductive hearing loss from sensorineural hearing loss. Furthermore, by measuring brain stem evoked response, it is possible to perform this test on individuals who cannot cooperate.