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Real Ear Measurement: Real Significant?

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In reply to @Neville

@Neville said:

But we measure loudness at the eardrum. So there aren’t missing factors.

the sounds we perceive aren’t produced solely by the ear drum, which uses as its gold standard. Far from that. Our complex middle ear structures and cochlear nerve are involved as well. We all should know this by now. REM doesn’t measure for the entire complex suite of outer/middle and inner ear processes that result in our perception of sound. More: the very shape of our outer canal, and middle ear, including the mastoid bone, determine much of how we hear, assuming a well functioning cochlear nerve. A tiny instrument shoved up against the eardrum does not measure all of these variables. Sorry. And for those of us with damaged ear drums, I doubt that REM will tell us much. Better to use your words!! and find a practitioner who knows how to listen, and has learned over time about different hearing conditions for different people. But again, it’s on us people to learn how to describe what we’re hearing to our providers. Even if what we hear differs from what REM tells us we should be hearing, based on an instrument planted on the outside our ear drum.

In reply to @wtolkien

Thank you for the explanation.

The procedure you describe compares (a) the sound reaching a mic outside the ear with (b) simultaneously a mic pointing in some direction inside the resonant cavity inside the ear with a hearing aid installed. Hard to see what any human adds because it could be done in a cardboard box (like quality control back at the factory).

I suggest comparing (a) the mic inside an ear wearing an unpowered aid and a likely type of mushroom or other items with later (b) the sound with the fitted aid and powered. I suppose that can be done all at the customer’s fitting visit, although the “before” test does supplement the initial human perception tests.

On the web, anybody with a keyboard can pose as an expert. In my long and varied career I have done lots of acoustical and comprehension research, mostly with humans involved including with the Can. Hearing Soc. (a few blocks from my office), and in the famous anechoic chamber when on staff at Bell Labs. Dispensing audiology is a mixed science, art,and business, needing skills in all plus lotsa smarts in counselling elderly people with new technology. I only wish had such skills myself. Ed Vilchur, inventor genius of some hearing aid features was a journalist and HiFi nut.

In reply to @jeffrey

No, and cannot take measurements of your brain function either. No one has ever claimed that it can. So throw it all out. Good lord. While we’re at it, why do an at all? Just tell the audiologist what you can and cannot hear.

In reply to @Bentoronto

@Bentoronto said:

I suggest comparing (a) the mic inside an ear wearing an unpowered aid and a likely type of mushroom or other items with later (b) the sound with the fitted aid and powered. I suppose that can be done all at the customer’s fitting visit, although the “before” test does supplement the initial human perception tests.

To what end?

Here’s a graph to help:

image

So at 55 you’ve got the unaided response, the occluded response (as you say, non-functional mushroom in the ear) and the aided response (whatever the hell you decide to set the hearing aid to) and you compare the to the and. . . what? What is it you are proposing one should DO with that comparison?

I really am just very curious at this point.

Is it that you thought that was trying to produce a flat curve and arguing that this wasn’t right because the unaided curve at the eardrum of a flat loudspeaker isn’t itself flat? Was that actually all that you were trying to say and I took it for something more? Because you’re right, the curve at the eardrum wouldn’t be flat. But. . . no one thinks it is and REM is not trying to make it so.

Neville -

Nice charts. Thanks. It is the funny wavy curve that illustrates why you need a baseline to know if the measured curve approximates what you are looking for with the aid boosts. Nicely illustrates the 4kHz canal resonance too…. which illustrates my point again.

All intake testing should always be done with the customer wearing a mushroom and dummy .

As far as I can tell, testing has little value except to confirm the factory didn’t goof. But it can only do that by using a just comparison (“before” baseline) or in comparison to a generic/average curve. REM can have something to say about the mushroom “crossover”, mentioned below.

The serious action takes place after the eardrum. So we are ultimately reliant on the human’s perception. REM has little to add about that.

The mushroom presents an impediment to hearing. And the imponderable estimation of the crossover behaviour needs to be gauged - by-pass or mushroom leakage is considered kind of roughly by the audiologist. “Crossover” is a HiFi term for the way a woofer and a tweeter divide the tonal spectrum. Likewise for division of the tonal spectrum between the aids and the sound that by-passed the mushroom. My audiologist hadn’t a clue what I was talking about.

@Bentoronto said:

customer wearing a mushroom and dummy HA

Could you clarify what you mean by mushroom? Some sort of dome or ear plug?

Is not doing that measurement with the aid in but without gain? One can have measured and at least one pro here does it even with adults. consolidates several measurements for an easier workflow and makes some assumptions it can sort of get away with for many patients.

If you are suggesting some like tweaks beyond REM, I’m not sure anyone would disagree. There are many possible reasons but that seems beyond the thread.

In reply to @Bentoronto

Do you understand ?

Do you understand discrete SPL measurement in the ear canal?

Before you make any more comments you might want to look this up, particularly the in the reasons for measurement of .

The concept of is a little difficult to visualise, but if you forget all the other measures and just understand that REAR measures the total net effect of sound at the eardrum, thereby proving what is delivered to the drum.

There are retrocochlea functions, but we’re not surgeons, we’re taking about fitting hearing aids.

In reply to @Neville

@Neville said:

No, and REM cannot take measurements of your brain function either.

the middle ear anc cochlear nerve are not part of “brain function”. As for : these DO measure middle ear function and can isolate and measure cochlear nerve functionality. Audiograms measure the whole suite of structures that produce sound for any individual. measures sound at the outer side of the ear drum, period. So your suggestion about not using audiograms misses the point. I’m not against REM! I’m jsut pointing out its limits. Oh and shape of the ear cavities play a role too. REM is held by many folks here as a Gold Standard. Tenkan suggested its just another tool in the tool box. this last seems more accurate to me.

Something puzzles me about the skepticism among some regular posters here. I haven’t seen anyone question the usefulness of fitting rationales like or v5 or VAC+. There are disagreements on the merits of each, but no one seems to question their reason for being.

It’s an undisputed fact that just programming a hearing aid with the prescription generated by a hearing rationale doesn’t always result in the prescription being fulfilled at the eardrum. REM closes this gap. So how can you believe in fitting rationales but not in REM?

In reply to @jeffrey

I absolutely agree that is a tool. A gold standard tool. There is no one who argues that it should be used to the exclusion of everything else, only that it should be used. I frankly don’t really understand the relevance of the arguments that go “but it doesn’t measure [insert anything it doesn’t measure]". No it doesn’t. Therefore…. It needn’t be done? That doesn’t track.

In reply to @x475aws

@x475aws said:

Something puzzles me about the REM skepticism among some regular posters here.

Part of it is what I call “what worked for me”-ism. So “my audiologist doesn’t use it and he did a fantastic job, therefore…”.

“What worked for me”-ism is particularly rampant on Facebook. Drives me nuts.

In reply to @d_Wooluf

The funny thing is that I’m not as hawkish about as this conversation has now made me seem. When clinicians who do REM get together to talk about patient care, they don’t talk about REM. It’s just a standard, basic thing they do as part of preferred practice.

I could just see a bunch of Physicians getting together and discussing whether they should use a thermometer or if just feeling the person is good enough. And lengthy forum threads about how thermometers aren’t really necessary because you can already tell if the person has a fever, and how different people have different body temps so why measure it at all.

@birdcountry99 said:

Great analogy! ………….

ummm…no. A standard hearing test would be a better analogy to a thermometer. Who takes an test to plot their ? No one. REM can’t plot an audiogram. It also can’t take your temperature.

Please stop with the whole “those who point out the limitations of REM are imbeciles” stuff.

In reply to @jeffrey

A thermometer is simply a thermoscope with a scale. … I propose to regard it as axiomatic that a “meter” must have a scale or something equivalent. … If this is admitted, the problem of the invention of the thermometer becomes more straightforward; that of the invention of the thermoscope remains as obscure as ever.

— W. E. K. Middleton, A history of the thermometer and its use in meteorology

Thermoscope

In the late 16th and early 17th centuries, several European scientists, notably Galilei[4] and Italian physiologist Santorio,[5] developed devices with an air-filled glass bulb, connected to a tube, partially filled with water. As the air in the bulb warms or cools, the height of the column of water in the tube falls or rises, allowing an observer to compare the current height of the water to previous heights to detect relative changes of the heat in the bulb and its immediate environment. Such devices, with no scale for assigning a numerical value to the height of the liquid, are referred to as a thermoscope because they provide an observable indication of sensible heat (the modern concept of temperature was yet to arise).[2]

Given that a thermometer is a reading of the physical change in height of the column of water with values attached, I think it is actually quite fitting even when stretching the analogy further than intended. A real ear measurement is simply a measure of the sound pressure level near the eardrum. The is irrelevant to that measure. But useful information to be used with the audiogram.

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