Pinnae (singular, pinna) are the ear flaps you can sec on the side of your head, and they are simply collecting funnels for sounds.
A little way inside your head, sounds hit a thin, tight wall of skin, called the eardrum, making it vibrate.
When the eardrum vibrates, it shakes three little bones called ossicles. These are the smallest bones in the body.
The three ossicle bones are the malleus (hammer), the incus (anvil) and the stapes (stirrup).
When the ossicles vibrate, they rattle a tiny membrane called the oval window, intensifying the vibration.
The oval window is 30 times smaller in area than the eardrum.
Beyond the oval window is the cochlea – a winding collection of three, liquidfilled tubes, which looks a bit like a snail shell.
In the middle tube of the cochlea there is a flap which covers row upon row of tiny hairs. This is called the organ of Corti.
When sounds make the eardrum vibrate, the ossicles tap on the oval window, making pressure waves shoot through the liquid in the cochlea and wash over the flap of the organ of Corti, waving it up and down.
When the organ of Corti waves, it tugs on the tiny hairs under the flap. These send signals to the brain via the auditory nerve, and you hear a sound.