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Why is Fitting Reverse Slope Hearing Loss Difficult?

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I am in the process of shopping/trialing for my first pair of . It seems I have a relatively unique hearing loss, given that I have had a reverse slope loss my whole life (right ear) and never previously worn aids, and after a bout of SSHL earlier this year, my left ear’s loss turned into more of a “traditional” hearing loss curve. Prior to that bout, my left hear had been similar to my right. I actually had no idea that my reverse slope was pretty uncommon, and am even more surprised my audiologist hasn’t even mentioned it (though I am very happy with the care he has provided me thus far). But you can bet that my first question to him in our next followup will be whether he has fitted patients with reverse slope before!

I have been digging a little recently about reverse slope loss, and it seems that it is more difficult to fit this loss, but I’m still not gathering exactly why that is in today’s world of HAs. And yes, I have read through Dr. Bauman’s article that has been referenced several times in past posts, so I understand that each individual’s sense of normal hearing and the target sounds we want to achieve seem to be a bit different than people with the “traditional” loss (Please know I use the term traditional loosely; I understand that each individual’s loss is unique!). Does the difficulty generally lie in an audiologist’s inexperience with fitting this lost vs. the HA’s actual ability to compensate for an individual’s loss? That seems to be what I’m gathering. Does simply understanding the fact you likely have to override some of the initial fitting curves provided by the brand software make it easier to fit someone like me? I know that I have seen a couple posts with members that are quite savvy (an older Phillips Hearlink 9030 thread), and I am definitely not at that stage yet given this is my first HA, so I am looking for my audiologist to optimize my aids to start. But hopefully over time, I will learn to tweak and adjust myself.

Have others here with reverse slope loss found that a certain recent tech HA works better for them than others? Again, I know that’s a loaded question and what works for someone may very well be terrible for someone else, even with similar actual hearing loss, but just asking to see if there’s any general consensus so that I can make sure to try it out for myself to draw my own conclusion! I did see some discussion on Oticon’s VAC methods being theoretically better suited for reverse slope. Any confirmation from a wearer with reverse slope?

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Others on here are much more knowledgable. Perhaps @Abarsanti can comment. From my understanding the biggest challenge is getting the balance between the low frequencies and high frequencies balanced out. It’s very easy to overwhelm the existing high frequencies with too much low frequency gain. Even though high frequency is “normal,” it’s often helpful to add a little high frequency gain to help balance things out.

It could just be a case of what I’m used to but I find the Nal-2 prescription works great for me with a slight increase in the bass frequencies. I also prefer to turn off or tone down all the bells and whistle features as they don’t seem to help with my loss.

One of the things with fitting hearing aids nowadays is that they are supplemental to your remaining natural hearing. For “traditional” sky-slop losses this is relatively easy: make a vent in the ear mold to pass through the natural sound and add the high frequencies that are needed to compensate for the high frequency loss.

With a reverse slope this doesn’t work, because to boost the lower frequencies a larger contained air mass is needed in your ear canal.This prevents the use of a large (or any) vent. Otherwise all the amplified low frequencies would just leak through the vent.
Unfortunately this leaves no room for keeping the natural high frequencies passing naturally and with that your entire sound perception will be through the hearing aid. This means that you may loose all hight frequencies that a hearing aid simply doesn’t pass through (roughly above 8-10 kHz) and also that any directional information is lost. Therefore this is much harder to fit than the sky-slope.

I’m not an audiologist, so correct me if I’m wrong please, but this is the easy explanation as I have understood this matter.

I remember reading a presentation by Donald Schum who was at the time VP of Audiology at Oticon that talks about how Oticon chose to treat reverse slope hearing loss in their VAC+ fitting rationale. I think it boils down to actually providing an emphasis on gains in the mids and some of the highs being helpful for those patients in terms of better speech comprehension, despite the fact that they don’t lose too much hearing in the mids and/or any in the highs. It seems to go against the conventional wisdom of trying to boost the gain in the lows to compensate for the hearing loss in the lows, but at least for better speech comprehension, the patients seem to be more receptive to this kind of correction for speech.

I don’t know what other brands do for reverse slope loss in their own fitting rationales, but Oticon’s approach kind of goes against the grain with respect to where they put emphasis on the gain, but at least it seems to work for their patient.

I assume that for music, it may use a more traditional approach than for speech, but I don’t really know for sure.

It’s interesting that several people have mentioned boosting the highs, or the lack of some natural highs being out of the range and not passing through the ear since I have (power domes in the case of my left ear). I originally had a demo pair of Paradises for a few weeks, then almost a month with Oticon Mores, now back to the Paradise Life. It’s interesting when I first started my More trials, I initially did not like the sound of them compared to the Paradise, but felt they were much better in helping me understand speech in noise. But now that I switched back to the newer Paradise, I now find that I don’t think they sound as good as the Mores. Perhaps it’s just the adjustment period to different aids, and in another month, when I trial yet another HA, I’ll say the same thing about it not sounding as good before I get used to it.

But to loop this back to high frequency gains, the one thing I have noticed is that the higher frequency sounds this time on the Paradise are definitely both sharper and louder (unnaturally so) than the Mores! Now, I don’t know exactly what my audiologist did in the initial fit, but if he did boost the gains on the high frequencies, I feel that it’s too much and it definitely isn’t working for me. Of course, I expect this to be able to be tweaked to something more comfortable so it sounds more “natural” to me.

In reply to @jcw11

I’m no expert either but I guess the prescription or fitting formula is a preset of gain rules that your audiologist picks to suit your hearing loss. These rules take into account your age, sex and degrees of loss across the frequencies.

The formula I use () is described below - other common fitting formulas and their descriptions can be found at the link underneath the text.

NAL-NL2 - This formula maintains the same aim as NAL-NL1, which is to make speech intelligible and overall loudness comfortable. In general, NAL-NL2 provides more gain in low and high frequencies, and less gain through the mid-frequency region. The National Acoustics Laboratory reports that NAL-NL2 will provider better speech intelligibility without increasing loudness.

https://www.starkeyhearingtechnologies.com/inspirehelp/si/Fitting/Fitting_Formula.htm24

In reply to @jcw11

@Sulaco said:

Nal-2 prescription

@jcw11 said:

Not going to lie, I’m a HA newbie, so I have no clue what this means!

When you enter in your to depict your specific hearing loss, the gain to compensate for the hearing loss is prescribed based on a set of rules. It contains basic rules like to boost gain where the loss is, but it goes beyond that, how to boost gain for better speech understanding, etc. This set of rules is called a fitting rationale.

There are fitting rationales like NAL-NL1, , v5.0 Adult, DSL pediactric, etc. that are “standardized” and are publicly available for any company to use. But sometimes the mfgs decide to develop their own fitting rationales that they think would work better for their HAs and their gain prescription philosophy and targets. For example, Oticon has their own VAC+ proprietary fitting rationale that’s available only on Oticon HAs. Beside optimizing it for their hearing aids, they also incorporate what they want to see as their own Oticon sound characteristics. Sometimes they also incorporate findings of how to best prescribe gain for special hearing loss curves (like the reverse slope or the cookie bites) to optimize for speech understanding.

On most HAs, you can choose to use the mfg’s own proprietary fitting rationale. But if you’re used to and prefer one of the standard fitting rationales, usually those are made available for you to select and use as well.

You are a wealth of information. Thank you! And now I will go drown in more hours of absorbing new things in the journey.

Two for my hearing not once did anyone say anything about reverse slope.
Original ENT said hum you have an unusual loss.
Got made at me because I didn’t buy the aids from him.
Second one just said make sure you have a good set of aids. To me he implied I can sell you some. I was already wearing Audibel.
I learned about reverse slope here on the forum.
Opened my eyes big time.
I went through eight audiologist at Audibel.
No one said anything about reverse slope until the present one.
She adjusted the aids for more i quess mid and high.
She new about reverse slope and how the fitting is different.
The aids are programmed the best since I’ve been wearing them, 4 years.
She understands my loss.
Throw in the left ear is distorted and my hearing can get really interesting sometimes.
Personally my experience with reverse slope is you need to have an audiologist who understand your loss and is willing to work with you too fit the aids to your satisfaction.
It will take multiple fittings to get there, and even then it won’t be perfect.

Thanks for the info! Have you found this strategy specific to Oticon (and Phillips Hearlinks, as I THINK you’re the one that had that thread)? Or would it be universal like for the Phonaks I’m trialing now?

Phonak doesn’t have a fitting formula optimized for rshl imo. However any modern aid could be adjusted to fit rshl; it’d just be more work to get it right.

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