Real Ear Measurement - Why Is It Important?

In this video, Emma discusses Real Ear Measurement (REM) - what it is, why it's important for a hearing aid fitting, and how it's performed. REM is a crucial step of a hearing aid fitting, but can be often overlooked. Having REM performed can often improve hearing aid benefit as it allows for the hearing aid to be programmed for your individual ear shape and size. Value Hearing strongly advocates REM for all hearing aid fittings and as part of an ongoing hearing aid maintenance program.



The following is a transcript from the video above.

Hi there, welcome back to Value Hearings YouTube channel.

I'm Emma, I'm a clinical audiologist and in today's video I'm going to touch on the topic of Real Ear Measurement or REM, which is a topic that comes up a lot in forums. It comes up a lot on questions on our website and we hear it a lot from our clients.

What is it? And why do we need it?

The inspiration for this video came from just last week when I had a client tell me that they'd heard from another provider near my clinic that REM was no longer needed. Real Ear Measurement was out of date and we didn't need it anymore.

He wanted to know, because he'd been watching our YouTube videos, he'd been reading our website and also he's a big fan of Dr Cliff who's got the most successful audiology YouTube channel in the world, and he talks a lot an awful lot about Real Ear Measurement and how important it is.

Are REMS out of date?

This person wanted to know ‘well, why did they say it was out of date? Is it out of date? What's the story here?’. So we had a chat and I explained to him that no, it's definitely not out of date at all.

Perhaps what this audiologist is thinking is that years ago, one of the significant reasons for doing Real Ear Measurement, was to make sure the hearing aids were actually doing what they said they were doing on screen. And yes, the technology has improved so we've been able to trust that the hearing aids are doing what they say they're doing on screen more than ever.

But that's not really what it's about.

Real Ear Measurement, as the name suggests, is taking your ear into consideration when we're fitting the hearing aid. When we're actually fitting a hearing aid, we use these prescription formula there's quite a few to choose from.

The majority of audiologists use either what we call the NAL-NL1, or NL2 prescription formula, or the DSL version 5 formula, and then also a lot of them will use the proprietary prescription formulas from hearing aid manufacturers as well.

But all of them are pretty similar to the NAL-NL2. Their prescription formula is not necessarily better than the ones the hearing aid manufacturers are using, but they're the ones that have the most data behind them and the most evidence behind them, so that's generally globally, the prescription formula that's used.

That formula is used then to calculate, based on your audiogram, what kind of levels of gain you're going to need to get you up to a more normal hearing level.

Doing better than 'average'

Okay, so we're trying to get the sounds more audible and normal levels for you, but keep it nice and comfortable as well. When we do that, that calculation is based on the assumption that you have an average adult ear. The average adult ear is kind of a thing, but everyone's ears are so different, like one ear to the next on one person can be so dramatically different.

And the other thing that can be so different, is the impact of the hearing aid coupling -  whatever dome or mould we've chosen has on your ear canal acoustics. We've all got different lengths of ear canals, different widths, different curvatures, so the actual shape of the ear canal can vary a lot and this can actually even change over time.

Obviously, when we're fitting children, their ears are constantly changing, but even in the elderly we see some changes as well and then for us guys in between, the acoustics don't necessarily change that much, but like I said, our ears can be so unique.

Depending on what hearing aid we're using, if we change the dome size, the dome type or we go for an ear mould, or a dome, all the acoustics have changed again, so we really need to check that.

The Real Ear Measurement is us being able to use this amazing prescription formula that has had a lot of research go into it but apply it even more accurately for you and your ear.

The evidence shows it works

I guess the reason why I get really passionate about this, is that there is so much evidence to show that this works. 

This relates to better outcomes, this leads to happier clients, it even leads to less adjustment appointments, leads to less returns of hearing aids, less hearing aids ending up in the drawers.

So yes, you can put a hearing aid in and just pre-program it based on the software and the calculations that the hearing aid manufacturers made, and that person will most likely have an improvement, and will notice that their quality of life is better. But it will almost definitely not be as good as if we do a Real Ear Measurement, where we're actually incorporating their personal ear canal acoustics.

It is incredibly important.

You can't just take a hearing aid from one person's ear and put it in another person's ear and expect it to sound the same. The sound that leaves the hearing aid changes quite a lot before it reaches the eardrum and we need to measure that.

Another obvious thing about Real Ear Measurements, other than that they're very evidence-based, is that they're objective. Most of the rest of our testing, which is really important, is subjective. Mostly we do obviously do some speech-in-noise testing in the clinic. We use questionnaires to get feedback from our clients. We don't just fit them to prescription and send them out the door and say ‘this is what it's going to sound like’. 

We'll make sure that it's comfortable for them. Because everyone is a little bit different, the only way to objectively test that the hearing aid is in the target that we want it to make, is using this verification method of real ear measurement.

REMS are not just for new hearing aids

It's really important, even as the hearing aids age. You know you've got a one, two, three, four, five year old hearing aid... parts have changed, perhaps that person's hearing loss has changed a little bit.

We need to recheck that. We need to do the Real Ear Measurements so we know that all the components of the hearing aid are working as well as they could be. The Real Ear Measurement is really powerful tool in an older hearing aid to figure out if something isn't working quite right. You, as a client, can't always tell these changes because they can be so gradual.

It's really important we actually do an objective test to see ‘well are they reaching target? And if not, can we get them to reach target? And if not, why?’

How is the Real Ear Measurement actually performed?

Well, it varies from clinic to clinic, and even audiologist to audiologists as to what protocols they use. But generally what you'll find is they place a little probe tube in the ear when you do not have anything else in the ear.

That little probe tube acts like a little microphone and it becomes acoustically transparent once we calibrate it so it doesn't have an impact on the ear canal acoustics -  very, very clever stuff.

Then we're actually able to measure your personal ear canal acoustics without having any hearing aid in there. It's also really important that we make sure that probe tube is in the correct position so it needs to be in a very specific position, not too close, but not too far away from the eardrum, for us to get the best reading and fitting off the hearing aids.

Then we put the hearing aids in switched off and that gives us an idea of your occluded response so what kind of hearing loss are we giving you when it's switched off, then we can take that into account then we switch the hearing aids on.

We will usually just check what the automatic fit from the hearing aid manufacturer looks like and take a bit of a recording of that to see how close or how far it is away from the actual target we're trying to achieve.

Generally, we'll play average speech at 65 DB SPL and then we'll play very loud speech at 80 DB SPL and we'll play very soft speech at 50 DB SPL. That is us just trying to see how the hearing aid responds to the different levels and volumes of speech.

We will then try to match target as best as we can. We use the hearing aid software to manipulate the gain handles in order to match that target that's being generated by the prescription formula as close as possible.

Obviously we then ask you how you feel about that volume and the sound quality. We will potentially make adjustments based on your feedback but this is a good starting formula for us.

So there you go!

Thank you for watching

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