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Fitting Formulas compared/

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Is there a site or document that compares the various Fitting formulas, i.e. , Nal etc.
Thanks

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Thanks tenkan. Yes Google is my friend. I was just wondering if someone here had done a bunch of research already since it is a topic. There is also a more in depth discussion over on Audilology on line. I have been using the prescriptive formula authored by Phonak in my L90’s. By using the Target software learning feature, I can visually (sort of) see some of the differences. I guess the best test is just to try them.

Edited

I wear Oticon More and have tested Nal-Nl1, Nal-Nl2, , and VAC+ (Oticon proprietary). We get considerably different initial results with each of those fitting formulas. That’s not surprising since they are regression models that rely on the assumptions and data they were derived from. If I were not comfortable tweaking them to my needs, I would hope to be lucky and be happy with one of those “averages”. Here are my impressions of the initial/suggested fitting for my hearing loss:

  • NAL-NL1: boosts midrange. Tiny low and high. I suppose it focuses on the human voice. It might be good for some, but it’s not my cup of tea. I like to hear everything I can.
  • : more balanced across the frequency range than Nl1. It is the one I use now, though not quite close to the initial fitting.
  • VAC+: similar to Nl2, though with a more linear compression scheme. I used it for the longest time, before switching to Nl2.
  • DSL vs5 adult: this is the one supposed to make you hear everything. Compression is the closest you get to a full linear. Oticon does not have the option to select semi-linear or linear compression, like Phonak does. I use this for my music program.

They tend to sound “less different” if set with similar gains across the bands, and I could not say whether one had an edge over the others. I guess in the end, with similar gains, these formulas are stuck with the same hardware and digital processing. However, I still hear subtle differences between them (or that is just my imagination!): VAC+ and NL2 sound smooth, perhaps. DSL sounds crisp, sharp, I’d say truer to the real input. Nl1 sounds tiny, not full.

Didn’t bother to look at Google :frowning: I assumed it had something to do with “tones”
BTW, I may have dreamed up Phonak Tonal. There is a Tonal available in Target 8 but not for Phonak. There is an Adaptive Phonak Digital 2.0 Contrast which was probably what I was not remembering correctly.
Anyway, if anyone is interested in an article discussing Adaptive Phonak Digital 2.0, someone sent me this link:

And there is an interesting article at Audiology online which discusses the differences between NAL-NAL2 and v5a here:

20Q: Same or Different - Comparing the Latest NAL and DSL Prescriptive Targets77

What? You say you don't believe in prescriptive methods for programming hearing aids? Really? Then let me ask you this: Your Monday morning patient has a relatively flat 60 loss of cochlear origin. Would you program his hearing aids with 60 dB gai

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