I agree. I’ve read all the ad copy and I even read a white paper on VAC (couldn’t find VAC+) and it was interesting but didn’t give me any real idea when one would prefer one rationale over another. Of course Oticon thinks VAC is better, but what do people who actually fit hearing aids think?
Generally new users are best at sticking with the manufacturers preferred fitting rationale (usually their own). They devised it with their own circuit and have done hours of testing with it. Where as NL1 and 2 are averages regardless of hearing aid. NL2 replaced NL1 as we found NL1 prescribed too high of gain at high level inputs and too little gain at soft level inputs. In addition to compression ratio’s being prescribed too high for those with severe-to-profound hearing losses. NL2 addresses the issues with NL1. Hearing aids are becoming more complex and “average” will only take you so far, hence manufacturers developing and tweaking prescriptive fitting rationales for THEIR aids. DSL is a pediatric fitting rational. We almost always stick with DSL fitting kids because max audibility is the #1 goal. Occasionally previous users won’t like hearing through a “proprietary” fitting rationale, in which case I will set them back to the rationale they have grown accustom to, most likely NAL-NL2. VAC+ is similar to Widex’s trusound compression strategy that REALLY tries to emphasis soft speech.
Thanks, SteveAUD. That’s good info. My doctor set me up with two programs to start: VAC+ and NL-1 (with the idea of seeing how I liked the flatter response curve). As you said, I definitely preferred the VAC+. At my recent 1-week follow-up I had had her just delete that program, which I had used less than 5% of the time.
Most manufacturers’ proprietary fitting formulas are geared toward initial acceptance. In other words, they usually underfit people so they’re more comfortable and won’t reject the hearing aids. Independently validated approaches such as NAL and DSL are optimized for speech intelligibility and preferred loudness levels. And DSL does have adult targets, so it’s not just for children.
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I take it, then, that you would recommend switching from VAC+ to one of the other formulas despite my initial preference for VAC+? And if so, could you give me an idea of when one would prefer NL-1, NL-2 or DSL?
I think it depends on what your goals are. If you want a very natural and comfortable sound quality, then the proprietary formula will likely work well. But if you want the best audibility of speech, NAL and DSL are both proven approaches. I would suggest that you try a verified (using REM) fitting with NAL-NL2 or DSL v5 and see how you perform on a speech-in-noise test, and then compare it with the proprietary formula.
Thanks for the inspiration! This morning I switched Alta Pros to NAL-NL2, Exact. I will try this for a while.
Oh I should say, Exact as opposed to Balanced or Gentle.
You’re stopping the Alta doing what it can by using a fixed formula like NAL. One of the main features of the Alta was the floating point linearity, which dynamically moves linear speech gain at different longer term ambient noise levels.
Without REM, it’s unlikely you’re getting an NL2 fitting. There was a report in Hearing Review last month that showed most manufacturers’ NL2 settings vary considerably from NL2 targets.
I checked with Oticon about this before and they told me Speech Guard is active even if you don’t use their proprietary formula. Also consider that Sensei Pro, their pediatric product, doesn’t contain VAC but still has Speech Guard.
I couldn’t hear any difference. I went back to VAC / Lively. Lively as opposed to Exact, Balanced, Gentle, or Steady.
Which is a good thing IMHO. But it also takes experience to know which manufacturers over do it and go in and make manual adjustments yourself. It’s also why all manufactures utilize some sort of acceptance manager to gradually build peoples tolerances up. I always err on the side of comfort to begin with. I never want people to walk out of my office with their aids on “edge” of being too loud. I’m not trying to give them some huge wow effect from the get go. We wake up in the morning and squint when we see bright light because our eyes have to adjust, the last 6-8hrs we haven’t seen light while we were sleeping. People walk around with aidable losses for 5yrs on average before they do something about it. It’s foolish to flip a switch and give them all this sound. I always warn people the first 2 weeks is what I call survival weeks. I expect you to come in and ask me to give you a little more, but I’m not going to force it down your throat from day one. Get use to hearing some thing through them, get used to physically having them on.
I have never in 15yrs heard a case to utilize DSLm[i/o] for adults as the results have been mixed at best. Again, we predominately use it on pediatric fittings.
In my case, NAL-NL2 was much better than the proprietary bernafon formula “bernafit”. But then again, bernafit is based upon nal-nl1, so maybe isn´t “up-to-date”. Maybe bernafon is working on a formula based on nal-nl2.
I like the NAL-NL2 fitting very much. It gives good amplification for soft sounds (where you need it) and doesn´t hurt your ears at loud sound (when everything is loud enough anyway).
Hi, Musician. I’ve been following your trialing odyssey in your various threads. When you trialed your Phonaks and Siemens did you have them tuned with NAL-NL2 also? Or did your audi use the manufacturers’ proprietary formulas? I am thinking of going back to the audi to ask her to try fitting my Phonaks with NAL-NL2. Do you (or anyone else) think that would be worth a try? Thanks.
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Hi,
with siemens I had both - first the proprietary formula, then nal-nl2, because the siemens technician thought that nal-nl2 might be better for music.
In case of the siemens, there was hard clipping with music, I´m sure. Couldn´t be avoided with any setting.
With phonak I don´t know, but it sounded (from the basic sound) very similar to the siemens with nal-nl2.
Note that nal-nl2 uses very much compression, more amplification of soft sounds, less amplification of louder sounds. This is perfect for my speech understanding.
For music, however, I have programs with less compression. Do you have an open fitting? What kind of music do you make? Maybe you can write me via pn, it gets very complicated here.
Regards,
Musician
I’ve been looking into the differenced between VAC+ and NL2. It’s interesting. Below are the maximum power output, targets, and compression ratios for my audiogram under each fitting rationale. Soft gain is significantly higher in my left ear under NL2, and compression ratios are higher. The thing that puzzles me most is the difference between the two rationales for MPO. Why is NL2’s MPO so much lower almost across the board than VAC+'s? And what would that mean in real terms?
| VAC+ | Right | Left | ||||||||||||||||||
| 250 | 500 | 750 | 1k | 1.5k | 2k | 3k | 4k | 6k | 8k | 250 | 500 | 750 | 1k | 1.5k | 2k | 3k | 4k | 6k | 8k | |
| MPO | 102 | 106 | 106 | 106 | 105 | 102 | 102 | 102 | 102 | 102 | 102 | 103 | 103 | 103 | 103 | 102 | 102 | 104 | 105 | 101 |
| Loud Gain | 0 | 0 | 1 | 2 | 3 | 4 | 5 | 0 | -1 | -1 | 0 | 0 | 1 | 2 | 3 | 4 | 2 | -1 | -1 | -1 |
| Mod. Gain | 0 | 0 | 1 | 2 | 3 | 4 | 2 | 0 | 1 | 1 | 0 | 0 | 1 | 2 | 3 | 5 | 3 | 2 | 2 | 2 |
| Soft Gain | 0 | 0 | 1 | 2 | 4 | 4 | 5 | 2 | 2 | 2 | 0 | 0 | 1 | 2 | 6 | 6 | 10 | 8 | 7 | 7 |
| Mod-Loud Compr. | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.2 | 1.2 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | 1.1 | 1.3 | 1.3 | 1.3 |
| Soft-Mod. Compr. | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | 1.1 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | 1.0 | 1.3 | 1.2 | 1.2 | 1.2 |
| NL2 | Right | Left | ||||||||||||||||||
| 250 | 500 | 750 | 1k | 1.5k | 2k | 3k | 4k | 6k | 8k | 250 | 500 | 750 | 1k | 1.5k | 2k | 3k | 4k | 6k | 8k | |
| MPO | 77 | 87 | 92 | 92 | 93 | 90 | 93 | 97 | 96 | 91 | 80 | 89 | 95 | 95 | 96 | 93 | 98 | 105 | 105 | 96 |
| Loud Gain | 0 | 0 | 1 | 2 | 3 | 3 | 4 | 1 | 0 | 0 | 0 | 0 | 1 | 2 | 3 | 3 | 4 | 1 | 0 | 0 |
| Mod. Gain | 0 | 0 | 1 | 2 | 3 | 3 | 4 | 1 | 0 | 0 | 0 | 0 | 1 | 2 | 3 | 3 | 5 | 5 | 5 | 5 |
| Soft Gain | 0 | 0 | 1 | 2 | 3 | 5 | 8 | 8 | 7 | 7 | 0 | 0 | 1 | 3 | 6 | 9 | 16 | 16 | 15 | 15 |
| Mod-Loud Compr. | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | 1.4 | 1.5 | 1.5 |
| Soft-Mod. Compr. | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | 1.2 | 1.2 | 1.2 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | 1.2 | 1.4 | 1.4 | 1.4 | 1.3 |
You have the chain compressor - limiter. The compressor reduces dynamic, but there still is dynamic. The limiter cuts off - everything above the mpo has the same loudness.
But if the compressor is compressing very much, you might not ever get to the area where the limiter limits.
Unless you set the mpo very (!) low, the other settings are more audible. If you set the amplification for loud sounds to “low”, your amplification stays under the mpo anyway, so the setting has no or little effect.
For me, the nal-nl2 is just perfect, because if loud sounds are amplified too much, I feel uncomfortable and understand less (!) than with a higher amplification.
Now the question: Is compression bad, especially for music? I´d say: No, but you have to be careful!
As for speech, it is said that the knee-point of compression should be above speech level, because speech is harder to understand when compressed.
What I do not understand: In most hearing-aid software, you set the amplification for 50 dB, 65 dB, 80 dB input levels. When I think about that, you should get two knee-points!
As for music, one must not forget that recorded music is always compressed. By using a microfone alone you get some (unwanted) compression. Even classical recordings are compressed a bit, because without compression one would always adjust the volume when listening in a quiet environment (like your living room).
Then people buy super-expensive valve-amps, and many think that they sound fantastic. But what do they do? They compress, and they add harmonic distortion.
What I am trying to say: Of course, compresion produces distortion, but it doesn´t necessarily sound bad. The distortion that really sounds bad is clipping.
One problem arises because of the open fitting of modern hearing aids. For frequencies below 250 Hz, you usually hear more “direct” sound than sound from the hearing aid. Below 100 Hz, you only hear direct sound, because the hearing aid cannot amplify that with an open fitting.
If you listen to dynamic music with bass in it, you will get the feeling that louder parts sound “dumb”, when your hearing aid is compressing a lot. This is because the low frequencies come through directly, whereas the high frequencies are amplified less at louder levels.
So what you can do is to reduce the overall amplification a bit and then reduce the compression just so far that the music you want to hear sounds good. This is a lenghty process, I had very much success by bringing some CDs to my audi.
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For me NAL-NL2 is very mild as compared to VAC+ which sounds louder to me. There is more speech clarity even with its lower loudness (as compared to VAC+) and I can watch TV without any streamer (Cant comprehend TV as clearly with VAC+)
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This is a very valuable and erudite conversation, from which I have learned a lot. It has prompted me to get my trusty audi to install a fourth program on my More3s based on NAL-NS2.
My objective is not to ultimately choose between VAC+ and NL2: VAC+ has already proved to be life-changing for me (yes - literally).
But I’m partially retired, and I spend many hours a day alone in our open-concept bungalow with tile floors throughout.
The tile makes it easier to clean up after 2 Newfoundland dogs and 5 cats, 4 of which are 16-year-olds with multiple health issues.
I asked for NL2 to provide me with an alternative to the VAC+ program that would give greater sensitivity to soft sounds occurring within a context of appliances humming and country sounds, incoming from the windows.
My audi only installed this today, so it’s not possible for me to report on its success, at this juncture.
I will report back after I have had sufficient time to habituate and truly discern the difference.
The VAC+ and NL2 programs are to be used in a rigorously-applied timetable: I won’t be toggling back and forth between the two. I’m pretty sure, however, that the NL2 paradigm is already letting me hear Daphne (Newf) sneakily licking at herself in the bedroom, creating fur tangles, because she has cleaned up a “Twice Eaten Hairball Delight” containing cat food to which she reacts alergically.
VAC+ will be turned on as soon as Mrs Spud gets home from her dog club meeting.
I would welcome comments on my VAC+/NAL-NL2 hotchpotch arrangement …
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