While the ear includes both an inner and outer area, the external portion actually goes by another name. Known as the pinna (and also auricle), this part of the body acts as an acoustic antenna and is made of ridged cartilage covered by skin. And, although its shape may look haphazard and random, the pinna’s structure of “hills” and “valleys” allow us to interpret the sounds of the world around us.
As the first in line to receive auditory stimuli, the pinna funnels sounds – like your favorite song on the radio or your friend calling your name – and sets a series of chain reactions in motion:
- Sound waves travel over the pinna into what’s called the external auditory canal, a short tube that leads to the tympanic membrane — a fancy name for what’s commonly known as the eardrum.
- The eardrum and attached bones are like a tiny kick drum that causes the middle ear to vibrate.
- These vibrations are conducted to the cochlea, a spiral-shaped part of the inner ear that looks similar to a snail’s shell.
- Then, the cochlea transforms sound into nerve impulses that travel to the brain!
These electrical signals represent a fascinating variety of sounds, like pitch. Did you know that low-pitched sounds in the eardrum vibrate slowly, while high-pitched sounds vibrate quickly? This means that a different signal is sent to the brain when you hear the bass in a song versus you’re excited friend calling to you.
If you step outside, what are some of the sounds you hear that you overlook in your day-to-day life?
Check out what else is going on this week in science!
