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how do we hear? how do we smell?
Our ears pick up sound which travels in invisible waves through the air. Sound occurs when a moving or vibrating object causes the air around it to move.

Sound waves travel down the ear canal and hit the eardrum in the middle ear. This causes the eardrum to vibrate. Three tiny bones in our middle ear link the vibrating eardrum to the cochlea in the inner ear.

The cochlea is filled with liquid that carries the vibrations to thousands of tiny hair cells sitting on a membrane that stretches the length of the cochlea. The hair cells on the membrane fire off tiny electrical signals. These electrical signals travel up the cochlea nerves of the auditory pathway to the brain. All this happens in a fraction of a second.


Our nose is a huge cavity built to smell, moisten, and filter the air you breathe. When you breathe in, the tiny hairs, called cilia, act like a broom and filter everything trying to get into your nose; from dust particles to bugs.

The air passes through the nasal cavity and though a thick layer of mucous to the olfactory bulb. The smells are recognized here because each smell molecule fits into a nerve cell like a puzzle piece. The cells then send signals to the brain via the olfactory nerve. The brain then interprets those molecules as the sweet flowers, or the curdling milk that you've held up to your nose.

Humans can detect over 10,000 different smells. The olfactory nerve picks up the scents from the air you breathe and translate them into nerve impulses or messages that are then sent to the olfactory bulb located in the front of the brain.


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