My current rabbit hole is the various fitting formulas or prescriptions. There seem to be three primary categories: , NAL, and manufacturer-proprietary. Among the latter is the Adaptive Phonak Digital () formula.
For ski-slope hearing losses the slope range is slightly boosted, typically the hearing loss range from 40-60 . Above this range the hearing loss compensation is continuously reduced. A typical result is a slightly higher gain in the slope range and a gain reduction above the slope in comparison to DSL v5 Adult.
Here is an excerpt from Figure 2 in the document. DSL v5 Adult is on the left, APD on the right; for each, the vertical axis is target gains and the horizontal is speech input frequencies. A typical ski-slope loss is represented by open circles, and the three gain curve outputs of each formula are for 85/65/50 speech inputs:
What I don’t understand is the motivation for APD’s reduction of gains beyond (what Phonak calls) the “slope range,” the frequencies having 40-60 dB loss. What speech understanding benefit might Phonak think APD yields relative to DSL by that APD gain reduction at higher frequencies?
Exactly, I don’t understand why the stress on which formula to use or not, I don’t know the answer to your questions, but you should pick one your happy with and then spend the time and effort into “fine tuning” your , I’ve tried them all and I’m happy with both the manufacturer proprietary and NAL, all the the others give me a headache! You choose.
What I don’t understand is the motivation for APD’s reduction of gains beyond (what Phonak calls) the “slope range,” the frequencies having 40-60 dB loss. What speech understanding benefit might Phonak think APD yields relative to DSL by that APD gain reduction at higher frequencies?
It’s apparent that the Phonak puts emphasis on more gain between the 1-2 KHz range, then slightly less emphasis with slightly less gain in the 2-4 KHz range, and much less emphasis with much less gain in the 4-8 KHz range, all relative to the adult formula.
Obviously Phonak doesn’t give any justification on why it’s doing that (or maybe they did in the material you saw but you didn’t share it here), so we can only guess. To me, they’re kinda saying that the 90+ loss in the 4-8 KHz range is very hard to compensate for and may lead to other issues such as feedback if driven too hard, so they might have given up on amplifying too much in this range because the return on investment is minimal so it’s not worth trying. Frankly, I agree with them because even for speech, there would be very little element of speech components that high up in that range. In a way, they’re saying that that heavy of a loss (around 95 dB loss) in that range is too far gone to recover, so why bother? You’re probably better off using their Sound Recover 2 if you truly want to access sounds in that range. And I would agree with them on this as well.
As for the 2-4 KHz range, they seem to give a fairly equal weight to amplification in the 50 dB input (soft sounds), and less weight on amplification for the 65 and 85 dB inputs. If I had to guess, I would say that it’s because they probably think that DSL gives too much emphasis on amplifying on medium and loud sounds in this range, which may result in a harsher tone than necessary than the user wants to tolerate, so maybe they think a less harsh, more comfortable amplification in this range would give a better experience to users. The soft sounds do get a slighly more boost at 2 KHz but slightly less boost at 4 KHz compared to DSL, again to make sure soft sounds are heard better at 2 KHz with APD but it’s not necessary to make it sound too harsh at 4 KHz.
Then at 1-2 KHz, the Phonak APD amplification seems to be much more aggressive than DSL. I think Phonak thinks that this is where a majority of the speech components resides, much more so than those above 2 KHz, so therefore more amplification emphasis here will give more bang for the bucks, so that’s why Phonak would prefer to put amplification emphasis where it’s more effective for speech and everything else.
Personally, I think that the Phonak APD would sound better overall and much less harsh than DSL, because DSL puts too much emphasis on the very high frequencies end, where Phonak prefers to put more amplification emphasis on where the majority of the sound components reside, below 2 KHz.
With this kind of very steep ski slope loss presented here, I think the Phonak APD strategy makes more sense, because more than likely, this kind of loss should be coupled with the use of the Sound Recover 2 frequency lowering technology anyway, so it’s not like you’ll lose all the high frequencies sounds if you’re going to recover them in the lower end with Sound Recover 2 anyway.
Very interesting thread. I found the document, and frankly, much of it is way above my understanding, at my current level of self programming.
A few things did stand out for me though, which I feel could explain why my UK NHS aids have been unsatisfactory for years now. My ski slope bottoms out around 70dB so, my loss isn’t as bad as mentioned in the thread, but I guess the Phonak treats me the same, especially with domes.
Our NHS Audiology tend to give you “first fit”, and send you out of the door. It’s free, but such a shame, as Marvels have so much going for them.
My tinnitus seems to start at about 2k and has other tones above that. My hearing for “s”, “f”, “sh” has been poor. It feels that lows and mids are booming a bit too, which I thought could be masking these speech areas, when (according to this), there aren’t really boosting them in the first place. My requirements will differ from others, I’m sure. Maybe I should research . Is this something I can do in Target?
Thank you, I’ve just done this, and the difference is astounding. Everything is now very loud, but also much clearer I may have to reduce some mpo’s. I can see why this wouldn’t suit everyone
It didn’t work well with vented domes, as the dotted feedback line cut straight through the other lines, so I swapped back to full domes, and the feedback line is much higher.
Yes, more occlusive – less vented – domes (or molds) will raise the feedback threshold.
A dotted/dashes feedback threshold line indicates that Feedback and real ear test has not been run. It’s a good idea to run it. After running it you also have the option of “overtuning” (raising) the threshold in order to avoid its reducing the gains (“cutting through the other lines”) at higher frequencies.
Wow, just been outside, and down the pub. Switched to P90s before getting in the pub, they were booming, with a perceived upwards masking. Will try again tomorrow
The guiding ideal of is audibility and the guiding ideal of is selling hearing aids. The latter goal should still end up somewhere reasonable since you can’t sell hearing aids over the long term if people cannot hear with them, but it does tend to lean a bit harder into “comfort and acceptance” rather than “rehabilitation”.
But the brain can’t hear what it can’t hear. And the brain adapts. Different people have different tolerances for rehabilitation. If you’re okay living with something that might start out sounding a bit harsh and giving yourself time to adapt, you may end up with higher function.
However, information that we do not have at this point are the time course and limits of that adaptation. So it can be admittedly frustrating not knowing how long you need to put up with something that isn’t perfectly comfortable in order to maximize gains.
This probably is not the answer you are looking for but it is my experience.
I spent a lot of time tuning for the best speech understanding.
Then tried . My speech understanding went down. I then fine tuned DSL over a months time for best speech. When best speech understanding was reached the gains turned out to be very similar to the APD gains from before.
I’m late to the discussion, but I’ll throw in my 2 cents. I think OP MIGHT benefit from because their high frequency loss isn’t too bad. They might actually benefit from more gain there. For profound high frequency losses (like my ) seems like DSL throws gain to areas that can’t benefit. Remember that Phonak throws in (Sound Recover 2) as an alternative way to make high frequencies audible.
For profound high frequency losses (like my audiogram) seems like DSL throws gain to areas that can’t benefit.
Does “throwing” this gain have a cost that manifests elsewhere in the frequency range, or is the cost only potential loudness discomfort and/or feedback issues?
I think mainly the later. IF (I don’t think yours is, mine is) your high frequency loss is because of a dead cochlear area, more gain will add distortion.
North West UK
