# A person is sitting in a quiet room when a loud sound is made behind them. Explain how the ear detects this sound and converts it into a nerve impulse that travels to the brain.

> Pearson Edexcel A-Level Biology A (9BI0) — 4.4 Vision and hearing · Explain · 5 marks

## Mark scheme (5 marks)

1. Sound waves cause the eardrum (tympanic membrane) to vibrate
2. The vibrations are passed through the three ossicles (malleus, incus, stapes) / the three small bones in the middle ear
3. The ossicles transmit vibrations to the oval window, which causes fluid in the cochlea to vibrate / move
4. Hair cells (sensory cells) in the cochlea detect the vibrations in the fluid and are stimulated
5. Stimulated hair cells generate / send a nerve impulse along the auditory nerve to the brain

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-person-is-sitting-in-a-554fcf08) · Published by Druglandscape Ltd.