Radiotherapy, and radiotherapy combined with chemotherapy, are common treatments for many head and neck cancers. However, these treatments can sometimes cause hearing loss or tinnitus (ringing in the ears), which can have a major effect on day‑to‑day life.

This study aims to better understand why these hearing problems happen and which parts of the ear are most affected. To do this, patients will have a range of detailed hearing tests both before and after treatment. These tests look at how well the tiny hair cells and nerves in the ear are working.

Researchers will then compare the hearing test results with the amount of radiation received by different parts of the ear. They will use advanced computer techniques to pinpoint which specific ear structures are most sensitive to radiation.

The goal is to use this information to:

• Set safer limits on how much radiation these delicate structures receive

• Reduce the risk of hearing loss in future patients

• Help doctors make better decisions about balancing effective cancer treatment with protecting hearing

What the study aims to find out

1. How radiotherapy to the head, neck, or brain affects hearing, including the tiny hair cells and nerves that allow us to hear.

2. Whether chemotherapy (especially cisplatin) combined with radiotherapy causes more damage to hearing than radiotherapy alone.

3. How different levels of radiation to specific parts of the ear relate to changes in hearing, using advanced computer analysis.

4. Which part of the ear is most linked to difficulties hearing speech in noisy environments.

5. Which hearing test is the best at detecting early damage and could be used in the future to identify problems sooner.

6. Confirm these findings in a separate group of patients to make sure the results are reliable.

Patients on this study will require extra auditory (hearing) tests prior to starting radiotherapy and afterwards.