Jack Bennett, International Clinical Trainer at the Interacoustics Academy, describes how to perform Real Ear Aided Response (REAR) measurements and how to interpret and adjust the hearing aid frequency response. He also covers the other responsibilities of the clinician during a hearing aid fitting appointment, including fine tuning, counselling, hearing aid orientation and arranging follow ups.
If you prefer reading, find the transcript below.
Okay, so now that we've performed our calibrate for open fit, we can move on to verify the hearing aids in the ear canal. So I've now switched on the hearing aids, and I can move into the REAR 65 test in my protocol. You'll see there's lots of information on this screen. And this is one of the key benefits of using a real ear aided response (REAR) protocol. It means that we're actually measuring in dB SPL, so we can display other information on the screen at the same time.
So first of all, we've got 0 dB HL, that's these crosses here. And these have been converted into dB SPL. We then have this next line here; the shaded area shows the patient's threshold again converted from dB HL to dB SPL. Next is the target defined by the prescription that we're using, and at the top the ULLs, so that shaded area shows the uncomfortable loudness level for the patient, giving us a really nice portion in the middle the dynamic range, the usable hearing of our patient.
So we want to make sure obviously, that we match the hearing aid as closely as possible to the target but remaining within this white area in the middle.
So Dennis, if you're happy for me to perform the measurement, we'll do our first measurement, and I'll explain what we've got on the screen. So all you need to do is keep nice and quiet and nice and still. And it will take about 12 seconds to run the measurement. Here we go.
Okay, so that's our first measurement that we've taken. So the red shows the right here, and the blue shows the left. So this is showing the response of the hearing aid and the absolute responses have altered the mixing of the signal in the ear canal as well. We can use the Delta Values at the bottom to help us define how far away from target we are.
So these negative values show that we're below target on the right-hand side across all frequencies. And on the left-hand side, we're very close to target in some of these frequencies. But again, we're still below target in the high frequencies.
So the next step is to make some adjustments to the hearing aids to bring them as close as possible to those thresholds. And then we'll run another measurement. We'll show you that we've got you closer to that target. So we run our first measurement at 65. Use the Delta Values to assess how far away from target we were. Then made some adjustments in the hearing aid fitting software.
I'm now ready to actually run my second measurement. So we can see if we're now closer to target. So Dennis exactly the same again, nice, and still and quiet. And I'll just run the measurement now.
Okay, so we can see we're now a lot closer to target, I'm going to use a few tools just to assess the quality of the fitting, and I'll discuss those now. So the Delta Values can show us that we're very close to target in all of the key frequencies, we are below target in at 8k on both sides.
But as you can see, the target is actually below the threshold of the patient. That's perfectly reasonable. It's something that's defined by the prescription. It's because those frequencies won't necessarily lead to higher speech intelligibility. So in these kinds of fittings, we're not trying to get the patient to hear every single sound.
Over on the right-hand side of the screen, I can show a bit more information. And for each curve that we've measured, we can see an SII (Speech Intelligibility Index), that's the percentage of speech sounds that the patient is now able to hear. It's a good way of defining the quality of the fitting alongside the target match.
If you're finding it a little bit difficult to see all of the different traces on the graph, you can actually change that color. It's very simple to do this, it's a right click on the curve, you want to change the color off, change curve color. Now you can see that second measurement on the right has turned green and it's made it easier for me to review, which was first in which was second.
So I'm happy with that 65 sort of the average speech level. So now I'm going to run a soft speech level just to see that we were still matching target in those levels as well. And then we can also review them all on the same screen in the combined view. So I'll press my next test in the protocol. And again, Dennis, you'll hear the same woman speaking saying the same thing, but this time she'll be quiet. So just checking that the quieter speech is still matching to target. Here we go.
Okay, so again, we can, we can review the results, we can look at the Delta Values to inform whether we need to make any changes. And we can make use of all the compression in the hearing aids to make these changes without affecting any of the other input levels. Looking at that, I actually think we're very close to target and we can move on to the louder stimulus first before making any other global adjustments.
So Dennis, this time, the speech will be a lot louder. And if it is uncomfortable at any point, please let me know. But I'm quite confident that it will be below that level that you will find uncomfortable. So here we go, here's the louder presentation.
Okay, so again, using the Delta Values to help me assess the quality of these runs. I think on the left-hand side, there's a couple of frequencies we could move and adjust. So I'll go to my hearing aid fitting software, make some adjustments, and then the run that measurement again.
To speed up the process of returning to the hearing aid fitting software, I can use on top mode, which is this button here. When I press this button, you'll see a smaller version of the graph. And I can have the hearing aid fitting software in the background as well. So I can make my adjustments and then run the next measurement from this part of the software here. When I want to return to the Affinity Suite, then just press the X and it will automatically bring up the software as I need it to be.
There is an option in this protocol to run a much louder presentation, a warble tone at 90 dB. This is recommended in some protocols just to make sure that the very loudest sounds won't be uncomfortable to the patient. It's worth reviewing whether that's relevant for every single patient, and in the particular room that you're in, you may find it uncomfortable yourself.
Okay, so I've now adjusted for all three input levels. And then I've also made fine tuning adjustments based on our patient's preferences. Having done that, I then rerun all of those measurements again, to especially to check that the 65 dB input level wasn't adversely affected by all of those fine-tuning adjustments.
As a final sort of quality control measure. I'm just going to review all of those traces at the same time by pressing the combined screen view like this. And I'm quite happy that this is a suitable and reasonable match the target so I can save these results and then move all the equipment from the patient.
And then most importantly, perform otoscopy to make sure that everything is in the condition that we found it in the beginning of the appointment. To save that I've got two options. I can either press save a new session or save and exit. I'll press Save and Exit now. So that's everything you need to know to perform a real ear measurement and hearing verification with the Affinity Compact.
It may be tempting to think that the REM process and the hearing aid fitting finishes here with a hearing aid that is matched to target perfectly. However, the fitting appointment is not finished at this stage. We still have a few more stages and steps to perform. After we've completed the aided measurements and we've matched a target.
We then need to make fine tuning adjustments based on the patient's preference to the sound. We also need to ensure they're oriented to the hearing aids correctly, that they know how to use them. And then of course, we need to arrange the follow up and the next steps with our patient. Never forgetting counseling throughout this entire process.
So let's look at fine tuning adjustments. If we've made a perfect match to target and then we have a conversation with our patient, we may find that depending on where they are in their rehabilitation, that they're not satisfied with the sound, or they may have some comments on the way that the hearing aids sound. Here are some common comments that you may get.
It may be scratchy or tinny. These are normally due to high frequency components. And especially for someone with a high frequency hearing loss - they're not used to hearing the high frequency components of the sound.
You may also have the patients complaining about the sound of their own voice. Assuming that you've eliminated the occlusion effect already, any complaints about the patient's own voice are likely due to excess low frequency amplification.
The patient might also just complain that the sound is generally too loud, or they might talk about an echoing sound at this stage. Just be cognizant of any feedback or any leaking of the amplified sound as they may actually be hearing a true echo.
The temptation with these is just to turn the hearing aid down to eliminate any of the complaints or the comments, and then intend to turn it up later on in the hearing aid fitting journey. However, there are tools that you can use to ensure the frequency shaping of the fitting is maintained.
Some manufacturer software will allow you to adapt what's called an adaptation manager, or perhaps their acclimatization manager, something like this. This is where the higher frequency components of the hearing aid response are turned down. And there are certain levels that you can set this to.
You can also make sure the hearing aid automatically turns up over time as the patient's been wearing it, ensuring that they automatically return to that perfect fitting, but helping them get used to the new sounds over a longer period of time.
So let's look at orientation. The first thing of course, is that we need to teach the patient how to insert the hearing aids correctly. So this is ensuring that the receivers or any of the components of the hearing aids are in the correct position inside the ears, and that they are secure and not going to fall out.
We also need to make sure that the patient understands the controls and the buttons on the hearing aids. You may have set a volume control or multiple programs for different listening situations. And the patient needs to understand how to control these different programs and volume controls. They also need to know about the audible indicators which tell them which program they're in or what volume that they are listening at.
We also need to make sure the patient understands how to clean and maintain their hearing aids. Clean and well-maintained hearing aids will work better and last longer. Next, we need to make sure they understand how to charge the batteries or change the batteries on their hearing aids. And they need to know how to do this safely and effectively.
Finally, we need to arrange any of the connectivity that is essential for the patient to use their hearing aids. This could be connecting to mobile phones, or television streamers, or remote microphones, any devices that you're using to effectively manage the patient's hearing loss.
And then the final stage that we actually need to undergo is to arrange a follow up and the next steps with the patient's rehabilitation. Hearing aid fittings do not finish at the first fitting appointment. You may arrange telephone follow ups or remote care appointments with your patient, or you may choose to bring them back into your clinic. You should arrange these things with your patient based on your clinic's needs and your patient's needs.
So I've said that counseling is essential throughout the entire fitting process. But what does counseling actually look like? It could be referring your patient back to any questionnaires that you've been using throughout your assessment and rehabilitation of the patient, such as the COSI.
You may also need to readdress or speak about the patient's motivation for actually wearing the hearing aids. It's essential to ensure that the motivation that brought them to you in the first place is maintained throughout the entire fitting process. As this motivation is what they're going to judge the quality of the fitting on further down the line.
Never forget about the patient’s communication partners. They need to know how to speak to people that they will be talking to on a regular basis about their hearing loss. Or ideally, whoever's the most important communication partner should actually be involved in some of the counseling throughout the entire process so that they truly understand your patient’s hearing loss and what they can do to help as well.
It's always worth referring to and teaching a patient about their hearing loss. Helping them understand that a hearing aid is not actually fixing the hearing loss but supporting the hearing that they do have. And finally, you should be looking at the expectations of your patient. What are they expecting from the hearing aids and ensuring that that aligns with what the hearing aids can actually do for them?