That was my thought from personal experience as I didn’t get along with NL2, and despite being told it works well for “everyone” I asked to change my Philips aid to DSL (adult) and haven’t looked back.
Obviously YMMV.
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My understanding is that the Philips HearSuite programming software doesn’t provide options to select which standard fitting rationales you want to apply to your program, like NAL-NL1 or NAL-NL2 or DSL Adult, or their own proprietary fitting rationale. So the assumption is that all built-in programs available to choose from HearSuite are based on the Philips specific proprietary, whatever it is (because it seems to be nameless and not spelled out in HearSuite).
If @withoutwings used to have NAL-NL2 and later asked to switch to DSL Adult, I’m assuming that it’s the REM adjustment that is targeted to match one of these standard fitting rationales. But it doesn’t mean that it is making actual gain computations based on the standard fitting rationale that was targeted to in REM. The actual gain computations will be based on whatever the proprietary fitting rationales that Philips uses. Although not named by Philips specifically, it’s probably based on the Oticon VAC+ fitting rationale because that’s where Philips licenses a lot of the hearing aid technologies from.
With Oticon aids, its programming software Genie 2 actually makes available 4 standard fitting rationales to choose from, beside VAC+. Therefore, it would actually be making gain computations using the fitting rationale that the user selects for that program. On the other hand, Philips will be making gain computations based on its internal fitting rationales, regardless of which standard fitting rationale was chosen to target to for the REM adjustment.
That’s incorrect: with Philips it is possible to select the intended fitting rationale as a global setting and it applies that to all programs, with the exception of the Hifi Music mode which uses its own special rationale. Typically you’d then do the REM fit on General to match your chosen rationale and leave all other modes (except music) linked to that one for fine-tuning purposes.
What you can’t do with Philips (or Bernafon) is select a rationale PER each mode; i.e. allow the user to switch between them if set up that way. As mentioned Oticon does allow this.
Both variants of each of NAL and DSL rationales are available for Philips, as well as two proprietary ones that are based on the older NL1 supposedly designed for a more “comfortable” fit. By all accounts Oticon’s VAC+ is far superior to either of Philips proprietary ones, and Costco (at least here in Australia) use NL2 as standard.
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Thanks for clarifying this, @withoutwings . Can you show me how to select and set a specific standard rationale I’d want on the Philips HearSuite software as a global setting? I just look at the Manage Program tab in HearSuite and only saw General, so it’s not obvious to me how General can be assigned to a specific rationale that I’d want.
Sorry for the probably stupid question and for dragging this thread further towards self-programming, but does this mean it’s inadvisible to change your rationale without doing a REM at the same time? I’m looking to experiment, mainly trying to find a sound that’s less harsh. Currently on NAL-NL2.
Ah, OK I see it now. Thanks!
Yeah so they say, so anytime you make changes to the fitting especially domes/molds, fitting formula etc you’d do REM… again.
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My understanding on this is REM does not need to be done if fitting rationale is changed. REM is verifying sound at the eardrum. Acoustics are the the criteria for REM, domes/earmolds and ear canal.
Seems I remember Neville talking about some REM testing equipment that only uses one type of fitting rationale. This forces the fitter to use that rationale for verification, then the fitting can be changed to whichever rationale is desired.
I sure might have this wrong but it makes since.
Let me get this straight… From what has been proffered above I have to assume that in most cases the audi has little impact on the settings generated/used for ones aids/hearing test results; at least initially.
Is that a fair representation?
Nick
I don’t really have the concepts yet, so I’m mainly playing with the nice simple switches and sliders that can easily be changed back. If anyone knows, changing the rationale from NAL-NL2 to DSL will result in a) a fitting that’s slightly out because REM was done to slightly different targets or b) a first fit (ie as if REM wasn’t done at all)?
One thing you can do is make the rationale switch. See how you like it. If you decide to put it back to the original rationale the prescription will be as before.
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I think it’s a little muddy here if the fitting rationale chosen after REM adjustment is completed is not the same as the fitting rationale chosen as the REM target. For example, VAC+ is designed to be more for all-around comfort and therefore less sharp on the highs compared to something like NAL-NL2, which was designed specifically for speech understanding.
So for example, if you can choose VAC+ as the target rationale of choice for REM, and let’s say that the hearing aids perform up to the VAC+ target, then no REM adjustment is needed. But if NAL-NL2 had been chosen as the target rationale for REM, but VAC+ is the actual rationale that is used, then it’s likely that REM will show that the hearing aids underperformed on the higher frequencies, hence REM adjustment will be made to bring the high frequencies up to the NL2 target. So now what you’re actually hearing is what NL2 sounds like (harsher) at the target level. You’re not really hearing what VAC+ sounds like (not as harsh) at the target level.
It’s not always a given that the HCP can choose a proprietary rationale to be the target rationale, however, unless the HCP has REM equipment that is compatible with the programming software (like Oticon Genie 2) and run REM inside the mfg’s software in order for the software to be able to calculate what the target value for that proprietary trainable is. An external REM setup would not be able to calculate what the proprietary rationale target values are because the formula is proprietary and is not available to external third party equipments. Only the standard rationales are available for third party equipments to do target value calculations on because the standard rationales are not proprietary.
Not an expert, but asking one of the pros might clear the air.
Fitting algorithms are are pretty well set for a given hearing loss. Once the hearing loss is entered into the software a prescription is made by the software.This I believe is standard information across the hearing industry, not brand specific. Knowing this and also knowing REM is for acoustic deviations to verify and adjust proper sound at the eardrum to meet the prescription.
So it makes since that changing fitting algorithms would make no difference to REM because sound levels have been properly set for acoustics and a calculated algorithm.
Does this clear the muddy water a little.
I may be way off on this but it’s just logical.
Don’t mind being corrected.
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I had this discussion with @Neville a while back and he confirmed with me that if NAL-NL2 is set as the target curve, any REM adjustment done (by manually changing the gain values) to fit this NL2 target will make the proprietary rationale (like VAC+, if that’s what the program being REM adjusted is set for) sound like NAL-NL2 at the target level. He’s copied here so he can chime in if my recollection of what he said is wrong.
So with my example above, if the hearing aids are performing to VAC+ target level but are shown to under perform at NL2 target in the highs (due to the difference between the 2 rationales), and REM adjustment is made to match the NL2 target curve, then the VAC+ based program will have been modified and will no longer sound like VAC+ but will now sound like NAL-NL2, at least at the target level. At other levels, it might sound like a combination of the two maybe, but it won’t sound exactly like VAC+ anymore.
Thanks, curious what is said. I seem to remember him/her talking about this. I thought it was to basically build an algorithm that wasn’t available and maintain REM gains.
I sure might be way off on this, will learn something either way.
Okay, incoming coffee-fueled saturday morning write-up.
Prescriptive targets are the amount of gain recommended at different levels and frequencies for a particular hearing loss. NL2 (Australia) and DSL (Canada) are the modern winners for adults (although people will still use NL1 in certain places, or even CAM) and they have converged over time as research has tried to optimize them, which you might expect they would if there is truly some sort of platonic ideal for gain prescription. There are still differences stemming from underlying ideology of how they were developed and you can generally expect NL2 to be a little bit more compressed, less loud/sharp. Currently research comparing user outcomes shows that people do well in both prescriptions with DSL maybe having a very small edge in noise situations, but the evidence base there is too small to really lean on. For children, DSL has separate child targets that are generally the only ones used; they have a strong focus on audibility are and significantly louder than adult targets. (Note, users who grow up with child targets are not and should not be transitioned to adult targets once they are adults. Adults with later onset hearing loss may do very well in child targets, but many cannot accept them due to loudness tolerance issues). Proprietary targets are developed by manufacturers largely based on NL2 and reasons for their differences are mysterious and may include increased initial user acceptance (# hearing aids sold), marketting (“our hearing aids sound ‘different’”), and internal research that suggests some change is good either based on small-n internal research or more recently large-n datamining (yay!). Historically, proprietary targets have on average just been quieter than independent targets which would certainly be the case if they were focussed on intial user acceptance. I looked closely at proprietary target implementation of current hearing aids last summer when I was discussing targets with Volusiano and that appeared to still be the case on average with the exception of Oticon VAC+ which is applying more gain than NL2 at 2kHz.
Whether a hearing aid is actually delivering prescriptive gain to your eardrum depends on the acoustic coupling and shape of your ear canal (effects can be huge), as well as the implementation by the manufacturer. There was research a while back showing that what the manufacturers called “NL2” actually differed quite dramatically from actual NL2 targets and from one manufacturer to another. Things have gotten better since that was ‘outted’, but there are still differences. DSL is a little bit more likely to be implemented in a static way across manufacturers because, as far as I recall, manufacturers need permission to use DSL and have to demonstrate to the National Centre for Audiology (that developed the targets) that they are implementing it following their guidelines. So the job of REM is to ensure that you are actually getting prescriptive gain and, yes, if you set a hearing aid to a proprietary strategy and then verify it against an independent stretegy and wrangle it to those targets across levels then you are essentially just turning it into the independent strategy. But remember that audiology as a whole is sort of a game of fuzzy precision. If you were fit to proprietary targets and then complain that the hearing aids are too sharp and the clinician rolls off the highs, you are now no longer using proprietary targets. If you do not have a perfectly kemar-average ear and first fit a set of hearing aids, you are not using proprietary targets. If the clinician only adjusts frequency-specific gain but not level-specific gain using REM, then compression strategies will still be proprietary although frequency strategies are now independent. And then the whole game is complicated further by neural adaptation and the limits thereof (e.g. hearing aids can sound one way at first and then your brain just readjusts over time and they sound natural again, so how much should you be tweaking them to comfort versus just waiting for your brain to get there).
You might imagine that if you set a hearing aid to NL2 and adjust it with REM so that it is taking into account your individual ear and meeting targets appropriately, then when you switch to DSL targets the hearing aid will just maintain the gain changes that were done to meet REM targets and apply them to the new prescription. This would be lovely, but it is largely not the case. There are even differences between manufacturers on whether they will do this for changes in audiograms. For example, if you input a new audiogram into a Sonova hearing aid it will (try to) simply adjust for audiometric changes and maintain fine tuning, but if you input a new hearing test into a Demant product it will try to just first-fit it again (annoying). For this reason, a clinician may regularly update the audiogram in the first product, whereas they may never update the audiogram in the second product for the life of the device and will simply readjust with REM for audiometric changes because they don’t want to totally refit.
Inputting a well-measured RECD into the software, if the software allows it, will typically get it closer to targets at first fit. The effectiveness of in situ to try to address this is, in my experience, not great. It’s maybe(?) better than nothing in a situation where a clinician does not have REM, but it is not generally the intention of the manufacturer that it be used in conjunction with REM in places where that is available–keep in mind that manufacturers are also trying to develop products for international situations where not only is REM not available, but audiometers might not even be easily available.
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Thank you so much for your excellent description of fitting algorithms and REM. Comparing hearing aid brands in this detail is something I can not do.
The differences between Phonak and Oticon might explain where Volusiano and I have different opinions.
Thanks again for your time, help and experience.
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I also have the Signia C&G 7-IX, they perform excellent for me and they are the newest from Signia, I am surprised your AuD is suggesting the Oticon Intent 1 since they are also the newest.
I have personally experienced that the programming and type of done used, as well as the receiver wire thickness has a lot to do with how well the HAs work for us.
I would highly recommend trying out first to reprogram the devices correctly, try out a thicker receiver wiring, and use the Tulip domes or even the custom mold to see how well they work for you.
We are talking a huge out of pocket expense that you might really don’t need. Have you also try to use the AirPods Pro2 exclusively for listening to music? If you have an iPhone you can upload your audiogram on the settings for the devices to adjust to your hearing loss.
Don’t give up, you can get those to work for you, you have the top of the line #1 best in technology with Signia.
Best wishes….
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Signia isn’t much appreciated on this forum. I also have the Signia C&G 7-IX and couldn’t be happier.
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