Real ear measurement vs. in-situ audiometry

How does that work, verifying against a set of targets different from the rationale that was chosen? In principle, the REM console could let you manually enter the individual patient’s targets as computed by the proprietary algorithm, right?

I could. But why would I want to?

Practically speaking, however, the proprietary formulas are all just based on NL2 with some degree less gain, mostly at the high frequencies, so that first time users are more likely to accept them.

@Neville said:

I could. But why would I want to?

Because if you’ve chosen to use a proprietary fitting rationale, it would let you verify the fitting directly against that rationale’s targets, I think?

But there’s nearly no case in which I would choose to use a proprietary rationale. If a hearing aid manufacturer locks certain features into their proprietary rationale, which is rare now, I’d still just select that in the software but then fit the gain to an independent target. For example, to turn off fast compression for certain patients I may choose Phonak’s adaptive digital contrast rationale, but then I’m still going to adjust it to DSL or NL2.

What if the manufacturer formula doesn’t offer the same gain vs the same input depending on the conditions for a window of time before the sample?

Serious question?

Floating point linearity shifts the amount of gain applied depending on long and short term averaging of noise and speech.

How are you going to plot that?

Edit: technically any dynamic gain system could cause issues in this regard.

@Um_bongo
Let me get this straight: proprietary rationale implies longer processing time? Is this generally the case or only with certain manufacturers?

@tenkan said:

I’d like to know this as well, as I’ve always been led to believe that REM cannot be used with the manufacturer’s proprietary formula.

To expand on @tenkan 's point, my understanding is that if a REM stand-alone system/equipment is used, then it’s natural to understand that this REM stand-alone equipment can only have access to the standard fitting rationales, hence without access to the proprietary fitting rationale of a HA mfg, it cannot perform REM against a proprietary target curve because it wouldn’t know how to generate one.

But I notice that the Oticon Genie 2 software as something called REM Autofit (see screenshot below). I assume that as long as the HCP has REM equipment that is compatible with the Oticon REM Autofit, then REM Autofit can deliver the proprietary rationale’s target gain curve to the REM equipment so that adjustment can be done against the proprietary target curve. This would solve the issue of a stand-alone REM system that can only be fitted against a open standard fitting rationale.

This is just my assumption because it seems to make sense, but I don’t know enough about REM equipment to know if this assumption is true or not.

@Volusiano said:

@Neville is saying that if the user insists on fitting the REM against the mfg’s proprietary rationale because the proprietary rationale’s target curve is made available to the HCP, it’s entirely possible and he can do it, although he still prefers to do it against NL2 for some reason.

Sorry, let me be more clear. When he asked, my brain provided me with a few options for hacking it, all semi-arduous, and some of them possibly specifically dependent on my having the particular brand of real-ear equipment that I have. I did not mean to imply that it was straight-forward. Sure, I’d give it a try if a patient asked for it. I wouldn’t choose to do it. But you guys on this forum are a bunch of weirdoes. I love you, but not once has one of my patients EVER asked for a specific rationale.

@Volusiano said:

they go through great length to make their own proprietary rationale that they think is best fitted for their HAs

What makes you think that this is the case? What do you think the manufacturer’s purpose/goal is behind making their own rationales? (Relatedly, who do you think your clinician is talking to when they “call the manufacturer”?)

@Volusiano said:

they go through great length to make their own proprietary rationale that they think is best fitted for their HAs

@Neville said:

What makes you think that this is the case?

Then why would the HA mfgs bother to come up with their own proprietary fitting rationales then? Just for fun? There has to be a good reason why they would bother to come up with their own fitting rationale that makes sense.

@Volusiano said:

they go through great length to make their own proprietary rationale that they think is best fitted for their HAs

@Neville said:

What do you think the manufacturer’s purpose/goal is behind making their own rationales?

I remember watching an education video on Audiology Online by Donald Schum who was then a VP at Oticon. He was talking about the challenges of fitting unconventional hearing loss type like the cookie bite type, and how many HA mfgs would use the conventional approach and compensate for the loss in the area where the hearing loss is present, which is the mid range frequencies. But the point he was making in that video was that through the research they did at Oticon, they find that doing that doesn’t seem to help and actually makes it worse. He said that their research showed that focusing on increasing in the mid-highs compensation gives a better result in terms of better speech clarity, despite the fact that it would compensate where the audiogram says compensation (or what little of it is needed) is not needed there to get a flat response. The point of the video was that they took what they learn (about how to treat the cookie bite loss to yield better speech understanding results) and applied it to their proprietary VAC+ fitting rationale.

So to answer your question, my understanding is that these are the types of things that an HA mfg like Oticon may want to promote their own fitting rationales over the standard rationales, because it would incorporate these things that they have learned through their research into it. And that’s why their fitting rationales are proprietary, to protect these knowledges that they learned through their research that are incorporated into the rationales. I’ve heard of posters on this forum (most notably @Abarsanti) who has a cookie bite loss and prefers to use the Oticon VAC+ because he thinks it works best for him compared to other standard fitting rationales.

Also, because they design their HAs, they know the strengths and weaknesses of what their HAs can do, so a rationale that is customized to the design of their HAs would be better than a standard rationale that would not have the proprietary data to know to take into account the HA brand specific types of things like performance and capabilities.

So let me respectfully ask the same question back at you, why do you as an HCP think HA mfgs come up with their own proprietary rationale for then? It’s not meant as a challenge, but more as a curiosity to understand the viewpoint of the HCPs on this.

@Neville said:

(Relatedly, who do you think your clinician is talking to when they “call the manufacturer”?)

Sorry, but I honestly don’t get the point of this question. OK, so I think my clinician who sold me Oticon HAs is talking to Oticon when they “call the manufacturer”. It’s really over my head the implication of this question.

@Neville said:

But you guys on this forum are a bunch of weirdoes. I love you, but not once has one of my patients EVER asked for a specific rationale.

Haha, I think it’s more like maybe most of your patients probably don’t even know what a fitting rationale is, much less that there are standard ones and proprietary ones. And I’d also venture to say that some probably don’t even know what REM is, although maybe more may know about REM by now especially if they watch YouTube videos from Dr. Cliff pounding on relentlessly about the value of REM.

Nevertheless, people like us on this forum hear and learn what these 2 things are (the rationales and REM), so it prompted it to spur a dangerous combination of questions on how these 2 things work together (or apparently not). Not really weirdos, but more like “inquiry minds want to know”, haha.

@sterei said:

proprietary rationale implies longer processing time

@Um_bongo said:

No, why?

Proprietary rationales may not necessarily give the same amount of gain for two identical signals if they are preceded by different average amounts of speech, noise or speech in noise.

REM measures the application of gain over an input signal - the target at a given frequency is ‘fixed’ by a fitting formula like NAL 2. What if Otiwhizzo 5 doesn’t yield a repeatable result as it’s generating a variable amount of linear gain, depending a window of previous measured sound.

How do you include that level of complexity in your REM screen?

Why not either measure against a good target like DSL/NAL2 or just retain a proportional speech window and make sure the average output gets to that?

So based on this, the explanation given is that standard fitting rationales like NL2 are static and predictable, but a proprietary fitting rationale from an HA mfg is most likely (or can be) dynamic and therefore may not give predictable and repeatable results then?

Is there a reason why the standard ones are static but the proprietary ones can (and likely) be dynamic? What are the pluses and minuses between these 2 types of rationales?

Obviously for REM test, a fixed/static rationale that is predictable and repeatable is better because you don’t want the target gain to change all over the map then. Is that why @Neville in an earlier post was saying that mfgs typically recommend verifying against NL2 for their proprietary algorithms? Because doing REM against their (most likely) dynamic rationales is really not optimal?

@Volusiano said:

Because doing REM against their (most likely) dynamic rationales is really not optimal?

Yes, exactly that, per my last answer. You end up with a series of potentially overprescribed aids which people return or don’t use; especially in noisy environments……

The Modernising NHS Programme went through quite a series of this as there were many early mandates that Hearing Aids ‘must’ be fitted to full DSL/NAL2 targets. Some manufacturers added ‘test/REM modes’ to meet the requirements of the fitting/REM, but in my mind that’s just cheating as the actual real-world performance of the Aid will differ (significantly possibly) under real world conditions.

And if you think about a system like Phonak’s Autosense - how do you determine which mode the hearing aid is in when you perform the test.

@Neville said:

not once has one of my patients EVER asked for a specific rationale.

In my 20 years of hearing aids not once has fitting rationales ever been discussed. I suspect they only use the software default.

@Um_bongo said:

And if you think about a system like Phonak’s Autosense - how do you determine which mode the hearing aid is in when you perform the test.

Where I am pediatric standards are that we verify all subprograms individually and all ANR and dmic settings, if activated.

@prodigyplace said:

In my 20 years of hearing aids not once has fitting rationales ever been discussed. I suspect they only use the software default.

And this is what the proprietary rationale is built for. Minimizing returns across the large number of clinics that do not follow preferred practice.

Isn’t the “official” line from Phonak (and I think most of the big HA companies) that the fitting should be verified with REM set to NAL-NL2 values? It’s like they give two messages. If you want to follow best practices, you should do REM. If you just want to sell hearing aids, just use First Fit.