# A student is investigating how the human ear processes sound. Explain how sound waves entering the outer ear are eventually converted into electrical impulses that the brain interprets as sound.

> OCR A-Level Physics B: Advancing Physics (H557) — 5.3 Astrophysics and cosmology · Explain · 5 marks

> The human ear is a complex sensory organ. Sound travels as a longitudinal wave through air, entering the outer ear and travelling through several structures before a signal reaches the brain.

## Mark scheme (5 marks)

1. Sound waves travel down the ear canal as a pressure wave / compressions and rarefactions
2. The pressure waves cause the eardrum to vibrate at the same frequency as the incoming sound
3. The small bones (hammer, anvil and stirrup) vibrate at the same frequency and amplify the sound waves
4. Vibrations are transferred to fluid in the cochlea, causing small hairs to move, with each hair sensitive to a different frequency
5. The hair sensitive to the incoming frequency triggers an electrical impulse via a nerve cell, which the brain interprets 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-fab0b392) · Published by Druglandscape Ltd.