How We Hear

When we detect sounds, or noise, our body is changing the energy in sound waves into nerve impulses which the brain interprets.  SOUND WAVES are produced when the air is mechanically disturbed.

Sound is measured by its:

• frequency - This is the pitch (high or low) of a sound -- the number of complete sound wave cycles each second.  High frequency noises are more damaging to hearing than low frequency noises.
• intensity - This is the loudness of a sound.   It's measured in decibels (dB).

When we hear a sound, this is what actually takes place:

1. SOUND WAVES enter the ear canal and cause the eardrum to vibrate.
2. VIBRATIONS pass through 3 connected bones in the middle ear
3. This motion SETS FLUID MOVING in the inner ear.
4. Moving fluid bends thousands of delicate hair-like cells which convert the vibrations into NERVE IMPULSES.
5. Nerve impulses are CARRIED to the brain by the auditory nerve
6. In the brain, these impulses are CONVERTED into what we "hear" as sound.

Now we will learn more about noise levels and their impact on our ability to hear.