REM - Real Ear Measurement ... what is it?

Since I wrote about having trouble with the adjustment of a new aid, someone asked me if I have had REM done, they said it was Real Ear Measurement. I asked my audi and she didn’t feel it was necessary with the new type of aids, but said in the future she could try it. I’ve tried a search, but nothing comes up that explains it. What exactly is REM, how is it done and would it help with the newer aids or someone with my loss?

I am not in the industry, only a user of it so this may be a halfast answer, but REM involves placing a tiny microphone along side the hearing aid speaker in the ear canal so that the fitting computer can “hear” the output provided by the aid. What qualities of the aid output and the ears response to them the computer monitors, I have no clue. I have had it done in each fitting session.


I would sugest it. In a way measures the volume of your ear and gives the target for gain to the hearing aid. No matter new or old hearing aid. The problem is that needs some knowledge to be done correctly.

Needs to know which features to switch off from the hearing aid and so on…

I would reccoment it. You had the fitting without now you can have with and see if there is any difference…

Real ear measurement is done by measuring the output of the hearing aid between the loudspeaker of the aid and the eardrum. This is done by inserting a hollow tube which samples the sonic output of the aid inside the ear.

I’m not so sure about the accuracy of measuring the output of an aid using a thin tube nor am I sure how such a measurement could be of much use. If fitting a hearing aid was a simple matter of measuring hearing loss and then calculating the gain requirements of the user, then REM would be invaluable. The reality is that fitting a hearing aid entails more than measurements and calculations. I sure wish that this was not so - it’s a major reason for dissatisfaction with fittings.

I am a fitter. I do not go a day without using my Real-ear-machine. It is an invaluable tool for hearing fitting. The formulas used for calculation of hearing aid settings are based on “average” natural ear canal resonance. This natural resonance of the ear canal affects the way the ear naturally amplifies certain frequencies. While most people are close to the average almost everyone varies slightly (or greatly) from the average data. On top of this the way the hearing aid fits and the size of venting can significantly affect the end result of the output of the hearing aid. REM are the only way to get anywhere close to knowing what the client is hearing (until we can somehow tap into the neurons of the brain and literally hear what our clients are hearing there is no better option). Don’t get me wrong this is not the be all, end all of hearing aid fitting. It is still a requirement to communicate with the client and make personal adjustments based on subjective responses. The REM does allow us to start at a point much closer to an appropriate starting point for the client IMHO. I would probably say that I adjust the hearing aids away from the manufacturers formula in 95% of my fittings (not always by a great degree but I believe every little bit counts). As with any tool the better the user is educated and familiar with the operation the more effective the tool is. My current real-ear machine uses speech signals as a measurement (the client hears a sentence). This is also a very good way of receiving subjective response from a client at different output levels (soft, medium, loud, maximum). In my province (Canada) it is a legal requirement that REM be performed within 30 days of EVERY hearing instrument fitting.

If you said that REM allowed you to use the formula fit 50% of the time, I’d say it was a valuable tool. As it goes, a 5% fitting rate using the software and REM is not too impressive.

In a previous thread a HOH person was having serious difficulty with the professionals adjustments so I recommended a REM.

Generally REM is done with a tiny microphone that is inserted near the ear drum. Using a thin tube is not the most accurate sensing method because the tube itself may introduce peaks and dips depending on length, diameter, and termination.

REM takes a bit of time and calls for a bit of skill. Not every fitter wants to take the time. Ed

Not every fitter wants to take the time because REM hasn’t been proved to be of much benefit. My guess is that if it has, then everyone would be doing it. In the end, it almost always comes down to the skill and experience of the fitter.

I find this shocking and inexcusable. A apologize for my tone but this attitude is harmful to the public and I will explain why I feel so, and why you should too.

Not “every fitter” takes the time to do REM for 3 reason (all of them poor)

  1. It takes time
  2. the equipment is expensive
  3. they are either too lazy and/or ignorant of the benefit

Not one of those is a valid excuse given the evidence of benefit.

This is perhaps the MOST adversarial you will ever hear me but this attitude is harmful to the public as it is justification to not do your best. Its ok for people to have opinions and share them. Many issues have no right or wrong but when something is validated to the extent of REM and people advocate against it without valid argumentsthen I believe that is harmful to the public.

Clients deserve REM or failing that coupler measures with RECDs. Some form of verification is imperitive. Anything less is lazy and irresponsible IMO.

Lets me address some of these comments individually to further my point (and please know I do not mean this as a personal attack, I am attacking this point of view only)

False. Show me a reference that tells otherwise, leading governing bodies and research centers all over the world agree on the importance of REM, where you have ever read its “not of benefit” is beyond me

Here is a ref that reports otherwise, its was one of the first google hits and thus easy for everyone to obtain. I gladly dig up a mountain of more specific refs from journals if anyone prefers

The fact is there is so much evidence to back REM that its assumed at this point as gold standard. To illustrate that point I’ll quote Jerry Yantz

…My guess is that if it has, then everyone would be doing it. In the end, it almost always comes down to the skill and experience of the fitter.
Everyone should be doing it, period. The reasons they are not are already listed above.

Make no mistake, REM is not replacement for skill, experience, expertise and counselling, but the reverse is far from true. The assumption that skill or experience is a replacement for measurement translates to me into being stuck in old habits, lazy or failing to stay current. I use the “current” lightly here, REM is decades old already.

By this argument hearing aids are inaccurate seeing as their microphones channel sound though small tubes as well…come to think of it, many hearing aid receiver tubes do the same don’t they? Are you saying you have as little faith in hearing aids as you do in measuring them?

You ask how could a measurement of this nature be of use? It tells you what the hearing aid is doing! Without that you only have a best guess from the fitting software. It accounts for individual acousitical differences from one ear to another, I hope and pray you have never fit a child with hearing aids as the output in thier tiny ear canals would be shocking.

No one is saying that you should ONLY do REM, just that you do it. Your argument that a fitting is more than just measurements and calculations is not a justification to not do them. A hearing aid fitting is more than just an audiogram as well, that doesn’t mean we should skip that too!

REM (or verification by coupler measures + RECD) may well be the MOST important step after the audiogram, without it you are assuming you know the hearing aids output matches the sensory loss, targets or fitting software. Huge amounts of published resaerch show that these assumptions are invalid. That there are people skipping validation measures it is sad in my eyes, that there are people advocating against them shocking and harmful.

Your ears deserve some sort of verification to know what the hearing aid is doing, anything less is cutting corners. If you have not had it done and you wear hearing aids, you should. You dont have to follow it blindly but to ignore a tool that can give insight into how your hearing aid is working is folly.

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Drez, please give me a link that verifies the effectiveness of REM. Please read the material yourself before asking me to spend the time to read a link you provide. Personally, I disagree with you. I disagree with most of the things that hearing professionals want the public to believe. That’s just my opinion and I have a right to it. Mostly, I’m a practical guy but you can call me a public menace if you like.

I completey agree with you on this one. No REM, no sale. It does not take long and actually safes much more time in the long run if you get your fittings right first time, than trying to use youskill and experience" to try and sort issues out without really knowing exactly what the aids are doing in the ear.

You are certainly welcome to your opinion but myself, the research community and the audiological community at large disagree with you. I don’t know that I’d call you a public menace as I’m sure your not malicious, you very well may have good intentions but I do view your opinion as harmful. As I stated, I’m not attacking you, just this viewpoint.

I have read and evaluated the information on REM and that’s why I told you to do the same which I do not think you have done. In addition I provided you with evidence to back up my point and asked you to do the same to defend your point, which you failed to do. In fact you failed to address any of the rebuttals I provided other than to state that you disagree. None the less, I’ll humour you and provide you with more evidence:

If you read no other reference here, read this one. It summarizes the issue well without technical aspects of hard research.

Moving on in the chain of evidence, first I quote Harvey Dillon, lead researcher for the NAL group in Australia. The same group that developed the world leading fitting algorithm. When asked if real ear measures should be done and if so on every patient he replied:


If your in the US and you want something closer to home, next I will reference Michael Valente PhD, past editor in chief of Trends in Amplification and current editor for American Academy of Audiology.


Valente M, Roeser R, Horsford-Dunn H. (Eds). Audiology: Treatment (2nd Edition). Thieme Medical Publishers, New York, 2007. p93

I now quote the DSL group from the NCA at UWO in Canada, developing team of DSL i/o fitting algorithm, the second most established fitting algorithm.


And just for good measure lets include a reference from Brian Moore PhD so that we have representation from Europe as he is a well known leading researcher from Cambridge. The summary from this article states:

Aazh, H., & Moore, B. C. (2007). The value of routine real ear measurement of the gain of digital hearing aids. Journal of the American Academy of Audiology, 18(8), 653-664.

Its not just researchers that feel this way, teaching programs agree. Find below a quote from Galster & Galster (2010)

“At a recent teaching hearing aids conference at the University of Pittsburgh that drew representatives from more than 30 AuD programs, the clear consensus was that probe-mic measures were an essential part of the hearing aid curriculum”
Galster,J.A, Galster,E.A.(2010) Recording the real-ear aided response through a hearing instrument. Hearing Journal 63(2) 32-35.

That provides you with 4 strong referenced statements backing the efficacy of REM from 4 individual research teams, in 4 countries all leaders in their field. On top of that you have the consensus of the majority of teaching programs in the USA.

In the event that’s not good enough for you here is a quote from the American Academy of Audiology (AAA):


This is not just AAA either, major professional groups and regulatory bodies across the world advocate for REM by either recommending it or requiring it. Some of these groups include as mentioned AAA in the USA, BSA & BAA in the UK, CASLPO, CAA, BCASLPA and PHAC in Canada. Professional bodies are made up of leading professionals in the field and their opinions are made up of the collective options of their members and thus the field in general. Regulatory bodies are in place to protect the public and thus are advocating for the best practice on behalf of the patient. The collective opinions of these groups makes a strong statement for the use of REM even if the research was ignored.

Your turn, defend your point and provide me with evidence otherwise. This is a matter of consensus and its repeated time again that REM should be done and the reasons for not doing it are unjustified. REM should be done or that failing some other form of electroacoustic verification that takes into account individual differences between patients.

I totally agree with Drez. Some form of verification is necessary. I prefer to use real ear speech mapping as my form of verification. I find that some changes need to be made with each manufacturer and it let’s me know what is happening in real time. It is an effective method (combined with others) to ensure a successful fitting. I personally believe that if this testing is not offered with every fitting that the patient should not purchase from the audiologist / dispenser.

Thanks for the links, Drez. My feelings about probe microphone verification is that there’s an “Uncertain correlation with hearing aid satisfaction.” That would be the major problem for me. Do you know of any research that shows there is any correlation with REM and patient satisfaction? Don’t give me a bunch of links - one good one would be OK. If REM does not help in a practical way with solving a patient’s problems or make the fitting process more efficient, the majority of people doing REM will continue to be the ones forced to do it. I have no problem with you or anyone doing REM - unless or course, you’re using this to merely impress your patients.

Those of us who do it, dont do it to impress our patients - most patients dont know it exists, let alone how it works enough to be impressed with it anyway.

It does correlate to patient satisfaction in the fact that it drastically cuts down that number of followup appointments required to get a satisfied patient. And as a side note, even if there wasn’t a strong connection to patient satisfaction, i’d still perform REM - its imperative to know how the HA is performing instead of taking a shot in the dark.

dr. amy

So as a patient, what does one do in the situation described? Your audi doesn’t do an REM, and when you ask they say you don’t need one?

Also, do you feel that not doing an REM in the initial fitting is a sign that you should find another audiologist?

REM (or verification in general) does help solve patient problems and can make the fitting process easier. I’ve had cleint perpetually unsatisfied with long term HA use, measured RECD + Speech Map later and they now have corrected audibility and a happy client. Turns out they had an unusual canal resonance and the fitting software has no way of knowing that. It can also verify what you suspect the issue is when your clients give you subjective feedback. (For oversimplified example, “It sounds tinny” -->REM shows peak at 3kHz, adjust by smoothing it out–>cleint happy VS . “It sounds tinny”–>no REM–>adjust by turning gain down 2khz±->client may still be happy but with reduced benefit at 2kHz and 4khz+) That example also shows how doing a good job might result in happy clients, but doing a good job + REM means they could do even better, however they might not be “happier” as they have no idea what they were missing.

The biggest problem I have with not doing REM is that you have no idea what you are doing, yoru taking an educated guess. You can be doing a perfect job one day and a poor job the next without knowing it. Even adjustments, two steps in one fitting software is different from two steps in another fitting software.

People used the same arguments for not using a fitting algorithms like NAL or DSL when they came out and asked for the same thing, a nice correlation between NAL = Happy. This is a difficult thing to provide however as it doesn’t account for acclimatization, it doesn’t account for if they are doing better but not knowing it, it doesn’t account for them doing better but not likely the sound (because you can surely have both) and it doesn’t account for people not knowing what it should sound like. Their brain is not trained for what it needs to hear and they often don’t like it, at least at first. We have evidence of this as Todd Ricketts presented data on the issues showing that the hearing aid gain settings that patients find most pleasant may not provide them with much, if any, benefit (Ricketts, 2009).

Without doing another lit review at the moment (sorry this adventure has exhausted my daily fill for medline journal searches :P) you’ll have to settle for me quoting the Aazh and Moore (2007) study which showed REM resulted in a batter fit to target and hope that you feel a better fit to target at least is to the clients benefit, after all that’s what the first fit is trying to do anyway…

For the record while most clients stare blankly while doing REM, it can still be a valuable counselling tool as it visualizes what the hearing aid is doing. This can be done with out trying to impress with your fancy machine IMO.


Aazh, H., & Moore, B. C. (2007). The value of routine real ear measurement of the gain of digital hearing aids. Journal of the American Academy of Audiology, 18(8), 653-664.

Ricketts TA (2009) OC fittings: Considerations regarding prescriptive methods and function of special hearing aid features. Audiol Online

Some do it later at your first follow up. There is also a chance they did an RECD at fitting (or previously) and SREM behind the scenes. I think the red flag happens when you ask for it and they fail to give a valid reason why they won’t give you one. Perhaps that’s just me but I want the best for myself and anyone unwilling to try and do the best for me perhaps isnt doing a good enough job.

IMO thats a sign to get a new audi because I now have no idea what they are basing choices on, habit, out of date information, whim, who knows. Don’t get me wrong. its just as bad for people to blindly match targets without taking other things into account but I think we at least have the obligation to try and use the best tools at our disposal to help make our decisions.

I’m not much interested in journal articles unless it’s a study on the efficacy of REM and patient satisfaction. I think that’s a simple and reasonable request if changing my mind on REM is your goal.

My experience is as a repair technician. I’m quite familiar with the programming and testing of aids, having built and tested thousands of them. I was the go-to guy for difficult programming problems at the place I used to work. My dirty little secret is that I would stick the aid in my ear and listen. You’re correct about the resonant peaks being a major problem. You’re also one of the few guys that are even aware of this. Most programmers assume that what they see on the screen is what’s really happening but that’s not quite right. Typically, I’d listen to the aid and remove the peak. Most times, I’d also boost up the highest frequencies - even if the client’s problem was feedback. It’s amazing what you can do if you actually listen to the aid.

Most of the programmers out there are screen jockeys but I’ve pretty much learned to not pay too much attention to the pretty graphs on the screen. I will hand you that - REM is probably a valuable tool if you’re the type to not able to listen to the aid directly by sticking it in your ear. As I say, that’s my dirty little secret.

Whenever, I program a hearing aid, I expect to see the patient a couple of times for a follow up. I don’t consider that a problem or undesirable. I may do probe microphone verification in the future but only to calibrate the aids for speech mapping which, I think, may be a good idea.

I’m not hip to the latest things but as far as I know, most REM is done with a thin tube. You are correct about the inaccuracies using this method. My guess is that the tubing gets squished if you lay the probe outside the aid and inserting the probe through the vent will also affect the readings. The truth is that the best way to do a REM is to have a dedicated channel for the probe in the shell but that’s just not done.

I have not seen a REM probe that place the microphone inside the hear - do you have any info on this?