bone conduction auditory brainstem response bone conduction auditory brainstem response bone-conduction auditory brainstem response or bcabr is a type of auditory evoked response that records neural response from eeg with stimulus transmitted through bone conduction. bone conduction auditory brainstem responsepurposerecords neural response from eeg types of bone conduction vibration of the skull results in auditory sensation. this is a way to somewhat bypass the outer and middle ears to stimulate the cochlea. von bekesy is credited with the discovery that at the level of the cochlea, phase shifted bone-conduction signals cancel out air conduction signals. bone-conduction works because all of the bones of the skull are connected, including the temporal bone, which in turn stimulates the cochlea. barany (1938) and herzog & krainz (1926) were some of the first researchers to examine the different components of bone-conduction hearing. tonndorf (1968) found that there are three different forces that contribute to the forces needed to stimulate the cochlea: distortional, inertial (ossicular), and external canal (osseotympanic) distortional bone-conduction as vibrations compress the bones of the skull, pressure is put on the otic capsule and the membranous labyrinth. this then compresses the scala vestibule into the basilar membrane in the direction toward the scala tympani. a traveling wave is created similar to that created by air conduction signals. inertial bone-conduction the ossicles are suspended in the head and loosely coupled to the skull. when the head moves, the ossicles move out of phase with the head, but still follow the same cyclic motion. this causes the stapes to move in and out of the oval window. when vibrations come from the mastoid, inertial bone-conduction is greatest below 800 hz. putting the bone vibrator on the forehead instead of the mastoid does not significantly create this affect. osseotympanic bone-conduction this type of bone-conduction also involves low frequencies. as a bone vibrator vibrates the skull, the bone and cartilage of the external ear receives energy, most of which escapes the unoccluded ear. some of this energy hits the tympanic membrane and combines with inertial bone-conduction, stimulating the inner ear. an example of this occurs when you close your ears and speak- your voice appears to be much lower in frequency. bone-conduction abr