1. How we hear
The Ear

2. Hearing Sound It has two functions: 1. Sense of hearing
From the Cochlea
2. Sense of balance
Three semicircular cancels filled with fluid
Vertigo: the sensation of spinning/ dizziness caused by the build up of fluid.

3. How the cochlea works
1. Eardrum: it vibrates in response to sound waves.
2. Three delicate bones transmit vibration from eardrum to cochlea.
3. Fluid in cochlea vibrates and creates waves that travels up the spiral.
4. Different parts of the spiral responds to different frequencies.
Narrow channel: short wavelengths
Large channel: long wavelengths
5. The nerves from the spiral then send to the brain.

4. Human range of hearing 20 Hz-20,000 Hz
We can not hear 50,000 Hz even if it was at 100 decibels!
Cats and dogs have a larger range because the design of their outer ears and mor sensitive inner ears

5. Hearing ability Hearing ability changes with time.
People gradually lose high frequency hearing with age.
Adults: can hear usually only up to 15,000 Hz
Children: up to 20,000 Hz

6. HEaring damage Caused by loud noise
The nerves signals that are sent to the brain are created by tiny hairs that shake when the fluid vibrates.
Loud sound can cause hairs to weaken or break off.
How can we protect our hearing?

7. hearing loss Are you aware that you may be losing your hearing?

8. Assignment:
Read the hand out and answer the questions on your own sheet of paper and turn in.
With your assigned partner, design a recording studio and EXPLAIN why you chose to design it that way.
Create a materials list for materials that Mrs. Branum should buy so you and your partner can build it!
Hint: Google recording studio design for help.