Structure of the ear

Medical Physics | AQA A-Level Physics

The ear has three sections: outer ear, middle ear, and inner ear.
Outer ear: the pinnaThe visible, external part of the ear that funnels sound waves into the auditory canal. funnels sound waves into the auditory canalA tube about 25-30 mm long that channels sound from the pinna to the tympanic membrane. It acts as a closed-tube resonator, amplifying frequencies around 3000 Hz., a tube roughly 25-30 mm long. Sound waves travel down the canal and strike the tympanic membraneThe eardrum. A thin membrane that vibrates when sound waves hit it, converting sound energy into mechanical vibrations. (eardrum).
Middle ear: three small bones called the ossiclesThree tiny bones in the middle ear: the malleus (hammer), incus (anvil), and stapes (stirrup). They transmit and amplify vibrations from the eardrum to the oval window. (malleus, incus, stapes) transmit vibrations from the eardrum to the oval windowA membrane-covered opening between the middle and inner ear. The stapes pushes against it, transmitting amplified vibrations into the cochlea.. The ossicles amplify the pressure by roughly a factor of 20 because the eardrum has a much larger area than the oval window ($\text{pressure} = F/A$). The Eustachian tubeA tube connecting the middle ear to the throat. It equalises air pressure on both sides of the eardrum. equalises air pressure on both sides of the eardrum.
Inner ear: the cochleaA spiral-shaped, fluid-filled structure in the inner ear. The basilar membrane inside it vibrates at different positions for different frequencies, converting mechanical vibrations into electrical nerve signals. is a fluid-filled spiral. Inside it, the basilar membraneA membrane inside the cochlea that varies in width and stiffness along its length. Different positions resonate at different frequencies, allowing the ear to distinguish pitch. vibrates at different positions for different frequencies, converting mechanical energy into electrical nerve impulses. The round windowA membrane-covered opening in the cochlea that flexes outward when the oval window pushes fluid inward, allowing the fluid to move. flexes to allow the fluid to move. The semi-circular canals detect balance.