Is the cochlea directly stimulated by vibrations reaching it through the medium of the solid bones of the cranium, or is hearing by bone conduction merely a modified form of air conduction?
It is generally assumed that vibrating bodies of sufficient intensity and frequency, such as tuning forks, when brought in close contact with the cranial bones are capable of exciting the organ of Corti via the solid medium and thus produce the sensation of sound; yet there is no experimental evidence to substantiate this general belief.
Kerrison,1 in discussing air conduction and bone conduction of sound, stated:
Sound is brought to the organ of hearing in two ways, (1) by air conduction, as when the vibrating body is at a variable distance from the ear, the sound waves being transmitted through the medium of the surrounding air; and (2) by bone conduction, as when the vibrating body
BECKER BM. HEARING BY BONE CONDUCTION. Arch Otolaryngol. 1932;16(3):364–369. doi:10.1001/archotol.1932.00630040374006