# Explain why a person with a damaged ossicle chain may struggle to hear quiet sounds, even though their eardrum and cochlea are functioning normally.

> AQA A-Level Physics (7408) — 3.10.2 Physics of the Ear · Explain · 5 marks

> The ossicles are three small bones in the middle ear: the malleus, incus, and stapes. They transmit vibrations from the eardrum to the oval window of the cochlea.

## Mark scheme (5 marks)

1. The ossicles amplify vibrations / increase the force of vibrations transmitted from the eardrum to the oval window
2. The oval window has a smaller area than the eardrum, so pressure is increased (pressure = force / area)
3. If the ossicle chain is damaged, this amplification / pressure increase does not occur
4. Quiet sounds produce only small vibrations / small pressure changes, so without amplification the vibrations reaching the cochlea are too small to detect
5. The cochlea / hair cells therefore do not generate electrical signals to send to the brain, so the quiet sound is not perceived

## Key terms

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

## Related

- [Revision notes for AQA A-Level Physics (7408)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-a-person-with-a-854a4499) · Published by Druglandscape Ltd.