What do the hearing test results categories mean?

Righty, how to explain this in a way that makes sense without making you run a very real risk of death by boredom...

All workplace audiometry tests are assigned one of four categories, with the definition of these categories and how to calculate them being given in L108 which is the source of the standards.

Audiometry standards are relative - they change

One important principle is that categories of audiometry result are relative and move, they are not fixed. What we mean by this is that when assessing someone's result the comparison is made against the expected standard of hearing for their age and gender, not against a fixed point. This is because hearing naturally deteriorates with age so there is no point comparing a bloke in his mid 40s to the ideal hearing standard of a woman in her early 20s. So, when calculating a category of result, the person's age and gender are both taken into account, and if there is a history of previous hearing tests available as well then that is also used for comparison.

This means that someone in their mid-40s could have a worse level of hearing than someone in their early 20s but have a better category of result because for their age, their hearing is good, whereas the 20 year old may have good hearing overall but for their age it should be better.

Categories of hearing test result for workplace audiometry

There are four fixed categories of result and all workplace hearing tests will be assigned one of these.  

Category 1

This is the 'everything is normal' result. It means that for the attendee's age, their hearing is normal. That doesn't automatically mean the hearing is excellent as if they are older then normal age-related losses will almost inevitably be present, but for their age it is where it should be. After their second test, Category 1 people are normally tested every three years.

Category 2

The best way to phrase this is 'normal-ish, but getting a bit low and towards the lower end of the normal range'. Category 2 means their hearing is still within the normal range for their age and gender but is skirting close to the lower limits of what is acceptable. It's a heads-up that care is needed. As with Category 1, no follow-up action is needed other than the ongoing retest programme, with the next test being due in about two years.

Category 3

This one means their hearing is below the expected standards for their age and gender - it is poorer than it should be. If there is no medical history supporting this loss, such as it being previously diagnosed or some other medical condition which impacts on hearing, then the recommendation is that this one is referred to a medical professional for further examination to try and determine the cause of the losses and if any treatments are available. It is important that Category 3 people wear hearing protection in high noise areas to stop any ongoing deterioration. 

Just to repeat the ‘it is all relative’ principle above, Category 3 doesn't necessarily mean their hearing is rubbish and that they are deaf, it means it is not as good as it should be for their age and gender.

This means Category 3 people do not have to be removed from high noise areas just because they are Category 3. Someone in their 20s may actually have very good hearing, just that it should be even better for their age.

Category 3 people are normally retested every year.

Category 4

This one is slightly different to the other three. The first three are all calculated by comparing the result against a reference standard for their age, but Category 4 is a calculation comparing the current result against a previous result for the attendee. It is a measure of rate of change and not a measure against a fixed standard.

This does complicate things a little as someone could be Category 4 because their hearing has deteriorated when compared against a previous hearing test, but their hearing could still actually be very good, it was just even better last time. It is important to remember therefore that Category 4 is an indication of change, not of level of hearing. It would have been handy if the HSE had given this a different name and not made it sound like part of the ‘1, 2 and 3’ level of hearing system!

As with Category 3, the standard is for referral unless there is something previously known which is causing the reduction and the retest period is one year.

One audiometry category only

In a hearing test, only one category of result is assigned to a person, which will be the lowest one they scored in an individual ear, so if someone is Category 1 in the left but Category 3 in the right, then their overall category will be 3.

Category saying ‘unilateral’

There is a sub-classification called ‘unilateral’. This means one ear is worse than the other, so you may see ‘Category 3u’ which means one ear was a Category 3, and the other ear was better.

If one ear is worse than the other, whichever is the lowest result will be the overall classification given for that hearing test.

Confusion caused by comparing audiometry results of different ages

It's worth clarifying again that all these categories of hearing test result are dependent on a person's age and gender. For all the lengths we go to to make sure the results are kept confidential, you can bet the mortgage that the first thing attendees will do is go back to their workplace and compare who got which category of result!

Confusion can then arise when someone with a Category 1 result has worse hearing than someone with a Category 2 or Category 3, then they get very head-scratchy and think something's gone wrong, but it hasn't.

Someone in say their 50s has a lot of leeway in the calculation for their result of where their hearing should be, taking natural losses over time and age into account. As the Category is based on how well they are performing for their age, the 50-odd year old could have good hearing for their age and be Category 1, but still have some quite big losses compared to a teenager. Someone in their 20s however could have small losses and be less good for their age than they should be, so come in as a Category 2 or even 3, but side by side their hearing could still be better than the person in their 50s. It is the impact of age which makes the difference.

This is one area where the explanation given to the attendee by the Technician is important rather than just saying ‘Computer says Category 3’ and using standard phrased based on the category.

We do not give written information on Categories of result

It is reasonably common to give a written instruction on what a category of result means but we do not and we chose to do this for a very specific reason. Over the years is has been exceedingly apparent that these bits of written information are largely rubbish as they are too generic and in the real world actually fit very few people.

For example, if you have a 25 year old woman who is Category 3 then her hearing may be excellent, while a 55 year old man with Category 3 hearing may be very poor. How you explain that result to each of those people is completely different even though their result is the same. With the woman a further small fall in hearing ability may be unnoticeable to her, while the chap’s hearing may be such that a similar amount of further deterioration means him crossing the threshold where he really starts to struggle to follow conversations and hear what people are saying. Both of them need specific advice on their hearing, but what the Category 3 means is slightly different to each of them.

Standard information sheets or letters are so generic as to be too bland for both and neither benefit. Always check what your provider is telling attendees - are they getting a standard pre-written statement based on category of result, or an explanation based on them individually and their unique circumstances?

We explain the result to the individual, detailing what it means for them specifically, and especially in relation to their unique hearing health and noise exposure history, both occupational and non-occupational.