What do the hearing test result categories mean?

Part of a noise assessment is to determine which people need to be included in a health surveillance programme which is an ongoing series of hearing tests for people exposed to high noise levels.

The hearing tests are categories according to criteria set out by the HSE in L108, and are:

Hearing test categories as defined in the HSE's L108.

What that means in English…

NIHL means possible noise induced hearing loss. That doesn’t mean it has been caused by work, it means caused by possible high noise exposures. That could be work, but as noise damage is permanent it could have been regular time in nightclubs 20 years ago, or a lot a headphone use, etc.

In the old days it was called Industrial Deafness but the ‘industrial’ was dropped as it implies a cause but as all noise has the same impact on hearing, whether it is a loud machine or music, then identifying possible noise damage cannot confirm a cause.

Category 1

Someone with normal hearing for their age. It doesn’t mean it is perfect as hearing is supposed to get worse with age. Someone who is 25 should have nigh-on perfect hearing to be Category 1, while someone who is 55 could have some fairly chunky reductions, but it is still normal for their age.

To be Category 1 there must be no signs of possible noise induced hearing loss (NIHL).

Category 2

This is where it starts to get a little trickier as Category 2 can be either:

• If their first test, someone who has some reductions in their hearing which are getting towards the lower end of what is acceptable for their age, but it is still a pass. No NIHL present.

• Or if their second or subsequent test, it can be someone who has good or even excellent hearing overall, but there are also some signs of noise damage present, but the testing is showing it to be stable and not deteriorating.

Category 3

There are three ways to end up as Category 3:

• Someone who has hearing which is weaker overall than it should be for their age.

• Someone who has otherwise good or even very good hearing, but they have signs of noise damage present which have not been identified before. If it is a first identification of the possible noise damage the HSE say they have to be Category 3 no matter how good their hearing overall.

• They have signs of noise damage which is getting worse compared to previous years.

Category 4

The HSE were really not helpful with their naming here as Category 4 is different to the others. The others are all a level of hearing against expectation for their age or where noise damage is present, but Category 4 means they have a significant deterioration compared to previous years. Category 4 is therefore a rate of change, not a level of hearing.

Someone can be Category 4 but still have excellent hearing, just that it was even better last time.