NAL-NL2 Precriptions

Below is a snippet from a thread that morphed into about 15 different topics so I’m reposting pieces of it below to follow up on this specific topic.

I certainly understand the jist of the study results but I’m missing something on the specifics of the two fitting methods: manufacturer’s initial fit approach vs. a verified prescription. My guess is that the initial fit approach is more or less programming the aids to a model target based on the audiogram and the verified prescription is validating (and adjusting) the prescription based on REMs?

If that’s the case then the method that’s always been used for me is the initial fit approach. And now having been using HAs for 20 years and three months into my 4th set I very much appreciate the fact that what users want vs. what they need may be much different. I have my 3 mo. checkup next week and that’s why this topic piqued my interest. While I’m extremely happy with my new HAs I have a severe loss and need every bit of help I can get and the ideas discussed here could conceivably bring some improvement.

Original question from MDB:

“My understanding is that NAL-NL2 prescriptions are based on considerable research to provide best speech understanding.”

Partial response from abram_bailey_aud:

Of the 22 participants, 7 preferred their hearing aids programmed to initial-fit settings and 15 preferred their hearing aids programmed to the verified prescription.
The data support the conclusion that hearing aids fit to experienced hearing aid wearers using a verified prescription are more likely to yield better self-perceived benefit as measured by the APHAB than if fit using the manufacturer’s initial-fit approach.
Of the 22 participants, 7 preferred their hearing aids programmed to initial-fit settings and 15 preferred their hearing aids programmed to the verified prescription.
The data support the conclusion that hearing aids fit to experienced hearing aid wearers using a verified prescription are more likely to yield better self-perceived benefit as measured by the APHAB than if fit using the manufacturer’s initial-fit approach.

Link to the study:

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There are two concepts here.

The first is which prescription is used to program your HAs. This can usually fall into one of two categories - manufacturers formula or an independently researched proscriptive approach/formula. NAL - NL2 is one of the independently researched formula - in this case from the National Acoustic Laboratory in Australia. This is their second version of their formula. Either type of formulae are implemented via the manufacturers software by making a choice on screen between the formulae offered by the manufacturer. There are other formulae (eg. DSL) more popular in Europe. The independent formulae are aimed at good speech discrimination with some consideration to acceptance.

The other issue is verification - this means using real ear measurements to ensure that the hearing aid is actually delivering what it is set to deliver to your ear. A small tube is inserted near your ear drum and then the HA. The tube allows measurement of the sound as it is presented to your ear drum.

Great info. Thank you.

My hearing loss is in the severe to profound range so I need all the help I can get. The clinic I use (HearUSA) is under the Signia umbrella so I imagine they use manufacturers formula. I recently purchased the latest and greatest of Signia’s ALDs and from your descriptions it sounds like NAL-NL2 and REM are a logical next step in my quest to hear better which I will pursue at my upcoming checkup.

Good Luck

Let us know how you get on.

I had the appointment yesterday and I was pleasantly surprised by the audi’s openness to trying out NAL-NA2 and doing REM. We did the REM and no changes were called for as a result but it did show that I am maxing out the HAs in certain frequency ranges which was no surprise given the level of loss. I ultimately declined the NAL-NL2 until I can do some further investigation and hopefully can start right here. The audi suggested that the main concern he has is that my ALDs (Signia Pure 13BT Primax 7) are far more advanced than NAL-NL2 is really designed for and that I would be losing some significant functionality since it won’t take advantage of everything the chip has to offer. Whereas the Primax software is of course designed to take full advantage of the features. So if that assessment is correct it’s a tradeoff between these advanced features and whatever benefits I might see from the NAL-NL2 algorithms. And he readily stated that he does have patients that prefer the NAL-NL2 but those are all people with very profound hearing loss whereas I’m just bumping up against profound above 2K. Does anybody have a sense of this issue about whether NAL-NL2 makes sense on the latest generations of ALDs? He’s perfectly willing to let me try it out and see how I like it but I’d still like some greater perspective on whether it even makes sense with these ALDs. I really don’t have any complaints with what I have and in fact they’re about as good as I can imagine, but that goes right back to the original topic of this thread about perceived vs. real hearing quality. Clearly my perception is good but if there’s something that can help with word recognition accuracy than it would be worth exploring.

I hope somebody else chimes in on this, but I don’t know of any features that you’d lose by using NAL-NL2. The only thing I can think of is their “Hearing Profile” feature in Connexx 8.3 (fitting software) I suspect it only with works with Smart Fit, but it seemed pretty gimmicky to me. The idea behind the “Hearing Profile” is that it’s supposed to customize the initial fit. It didn’t seem helpful to me. Again, I hope somebody more knowledgable chimes in, but I don’t think you’d be giving up anything by using NAL-NL2 (although it’s quite possible you wouldn’t be gaining anything either.

I don’t see why you would be unable to use the HAs software with whichever fitting formula is used. The fitting formula just gives the starting point for gain not the programming for individual sensed environments and how the aids respond to those. If you want evidence about the efficacy of each fitting formula for you then you could ask for aided speech discrimination testing with each and see if there is a difference. Otherwise try it for yourself and see if there is a difference you can detect.

You could ask your audiologist to explain in what way you would lose any functions with the NAL NL2 formula and what those functions are.

I have used NAL NL2 fitting formula with the Resound LiNX aids and LiNX² and the formula was fine. I switched to Phonak for other resons.

Reading this thread, it would appear that switching between fitting formulas is possible. However, I have just discovered that my Naida V90s were fitted using the Phonak Digital formula. This has given me a month of distorted hearing. Changing to NAL NL1, speech is now much clearer, but the HAs are useless in any situation outside the house.

I hope tomorrow I can get these set up by my audiologist using NL1. But from your post, am I going to lose any functionality?

NAL-NL2 is the latest version of the National Acoustics Laboratory formula. Each manufacturer has to work out the implementation for their HA. If it is available then I would choose NAL-NL2 over NAL-NL1.

Primax Fit in Connexx is the nal-na2 optimized for the special features of the Primax technology.

Thanks Psocoptera.

It makes me wonder why he would not use NL2. I have wasted a month of the trial, because he used Phonak Digital, which for some reason I cannot hear clearly with. Is that normal for someone who has used NL1 for twelve years?

I’ve seen studies that compare manufacturer’s fitting ton NAL-NL2 and typically one named manufacturer does better than the rest. Anybody have any info on which manufacturer that might be? If I had to guess, I’d guess Phonak. That’s based largely on “gut” from little things I’ve heard such as my audiologist calling Phonak’s sound “harsh” and that he usually tones it down a bit and that Phonak gives me the impression that they’re trying to help you understand speech, not necessarily “sound good.” They also seem to emphasize providing hearing solutions to children more than I see from other manufacturers.

Actually iirc it’s Unitron. There was some point made in one of their presentations that their software was using the NAL2 target.

Thanks. Not sure we’re talking about quite the same thing. I’m talking about if you select NAL-NL2 in the manufacturer’s software, how close does it get? Most really undershoot the highs. I’ve included an article that first deals with manufacturer’s fitting formula and then in the later half their NL2 fitting formula.

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That is an interesting article. I even read a lot of it. :slight_smile:

There have been a number of discussions about first fit here. First fit has been panned a bit by some of the informed providers who tweak it to what they consider an improvement.

I recall, and I think I remember it correctly, a Costco fitter saying that their first fit was one designed by Costco. I don’t know if that was just for their KS6 or all aids. It might be a contributing factor to why some aids were locked.

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I’m currently trying NL2 first fit and it seems good so far although it uses less gain then the NL1 fitting formula does.
I’ve been using NL1 since 2011 but thought I would try NL2 to see if it’s any better.

I read that long article and it has made me even more impatient waiting to be able to get to self-programming my KS7’s.
I remember the Costco fitter looking for my immediate response on initial fitting and I had some negative things to say and so she started into all her changes. But of course I might be negative…it’s new hearing!
Well now I want to go back to that and see how I respond to it in my own time.
Thanks for that article link.

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I’m very impressed with NL2. We have high winds here in England due to Storm Brian but I’m still able to have a conversation despite it being very windy.

I should say that I wear Phonaks mid range HAs.