Detecting Sound

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

1. The outer ear is called the pinna. It funnels the sound waves that the ear receives and sends them down the ear canal, which is part of the outer ear.

2. These sound waves travel through the ear canal and reach the eardrum, making it vibrate. Microphones contain a diaphragm, which works in a similar way to our eardrum, which is part of the middle ear.

  • Three small bones in the middle ear, known as the hammer, anvil and stirrup, are connected to the eardrum

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

4. Movement then begins to happen in the fluid inside the cochlea.

  • There are tiny hairs inside our cochlea that move in response to the movement of the fluid in the cochlea

5. These tiny hairs inside the cochlea convert the vibrations from sound waves into electrical signals.

6. The electrical signals are transported to the brain up the auditory nerve.

7. The brain translates the electrical signals to 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

A busy street has a noise level around 80 dB, which can cause hearing damage after prolonged exposure.

This is why workers exposed to loud noises for extended periods should wear ear protection.

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