Ear and Hearing

The Outer Ear

Sound energy spreads out from its sources. For a point source of sound, it spreads out according to the inverse square law. For a given sound intensity, a larger ear captures more of the wave and hence more sound energy.

The outer ear structures act as part of the ear's preamplifier to enhance the sensitivity of hearing.

The auditory canal acts as a closed tube resonator, enhancing sounds in the range 2-5 kiloHertz.

The Tympanic Membrane

The tympanic membrane or "eardrum" receives vibrations traveling up the auditory canal and transfers them through the tiny ossicles to the oval window, the port into the inner ear. The eardrum is some fifteen times larger than the oval window, giving an amplification of about fifteen compared to the oval window alone. You may reach information about the nearby structures of the ear by clicking on the item of interest on the illustration.