Detecting Sound

To explain how the human ear detects sound, we first have to look at the structure of the ear:

1. The outer part of the ear is called the pinna. It funnels sound waves into the ear canal, which is part of the middle ear.

2. These soundwaves travel through the ear canal and reach the eardrum, which is part of the inner ear. This makes the eardrum vibrate. Microphones contain a diaphragm, which works in a similar way to our eardrums.

  • Within the inner ear, there are three small bones: the hammer, the anvil and the stirrup

3. The three small bones pass the vibrations onto the next part of the ear, the cochlea (the snail-shaped structure).

4. The vibrations cause movement of the fluid inside the cochlea.

  • Inside the cochlea, tiny hairs detect the movement of the fluid

5. These hairs convert the movement from sound waves to electrical signals.

6. The electrical signals travel up the auditory nerve to the brain.

7. In the brain, these electrical signals are interpreted as sound, which we can recognise and understand.

Loudness

The loudness of sound is measured in decibels (dB)

An average conversation is usually around 60 dB

An average concert is around 115 dB

Keep in mind that an increase of 10 decibels means the sound is ten times louder.

Hearing Damage

Continuous exposure to sounds around 80 dB, such as on a busy street, can cause hearing damage. That’s why workers exposed to loud sounds for extended periods should wear ear protection.

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