# A student is investigating how the human ear detects different sounds. Explain how sound waves travelling through the ear canal are converted into electrical impulses that the brain can interpret as sound.

> OCR A-Level Physics B: Advancing Physics (H557) — 5.1 Thermal physics · Explain · 5 marks

> The human ear is a remarkable organ capable of detecting sounds across a wide range of frequencies. Sound enters the outer ear as a longitudinal wave, creating alternating compressions and rarefactions that travel through the ear canal before being processed by several structures inside the ear.

## Mark scheme (5 marks)

1. Sound waves cause the eardrum to vibrate at the same frequency as the incoming sound wave
2. The small bones (hammer, anvil and stirrup) vibrate at the same frequency and amplify the sound waves
3. The vibrations are transferred to fluid in the cochlea
4. Small hairs lining the cochlea move in response to the fluid movement, with each hair sensitive to a different frequency
5. The movement of a hair triggers an electrical impulse in the attached nerve cell, which is sent to the brain and interpreted as sound

## Key terms

- [electrical impulse](https://www.gradenine.co.uk/glossary/electrical-impulse)

## Related

- [Revision notes for OCR A-Level Physics B: Advancing Physics (H557)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-investigating-how-the-adfa18de) · Published by Druglandscape Ltd.