RSHL, KS9s, and custom molds

I have reverse slope hearing loss. In the past, I’ve had Phonak and KS6 hearing aids with either open or tulip domes. I saw a university doctor last year who suggested that I would benefit from custom molds. No one else has ever suggested that and it’s the same office that scheduled me for a CI consultation then charged me $400 for an unnecessary hearing exam because my insurance covered a CI consultation (which they decided was unnecessary after I got there), but not all of the other stuff they did. I’m not sure that I trust them with RSHL suggestions after that debacle.

Regardless, I’m in a different state now, insurance still doesn’t cover hearing aid related charges, and I’m happy with Costco. I ordered a set of KS9s, a dryer, and a tv connector that will be here the 14th. The dispenser called Phonak while I was in the office and confirmed open domes and targeting certain frequencies, so I feel comfortable that they will be a better fit than previously. My question is this: should I ask about custom molds with my loss or will the occlusion resulting deem them unsuitable?

Looking at your audiogram I would think you need molds but I am no expert. When my lower frequency hearing got down into the 40’s I finally decided to go the earmold route. The low frequency sound improvement was outstanding. Music sounded so much better.
But everyone is different.
I was able to make occlusion control changes when I first got earmolds that helped a bunch. Phonak Venture and Beyond aids.

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My concern is because I have RSHL. I’m afraid the custom molds may block out all of the high frequencies that I currently enjoy unless there are significant vents. If I have enough venting to let through the high frequencies, is the mold really better than the open domes? I’m not familiar enough to make the decision confidently.

@Neville @Um_bongo Wonder if you might comment on this.


MDB made the best suggestion.
Hopefully one of the pros will chime in.
You might even send them a PM for help. They are both a huge help on this forum. There are other pros that help too. Maybe one of those will help.

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Here is the speech banana attachment that might help. It looks like the banana didn’t come up. Search “speech banana” to see where you are.

My thoughts as an amateur is that your loss is a difficult one to fit a hearing aid for. I would have a long discussion with the fitter at Costco as to what the options are for you. Some issues to consider:

High Frequency - Yes, an open fitting will preserve your natural hearing of highs. Most hearing aids however can go out to 10 kHz, but after that you probably can hear higher if the sounds can get in the vent.

Feedback - Should not be an issue for you even with open domes. You do not need a lot of gain in the feedback sensitive 2-4 kHz frequency range.

Low Frequency Gain - This is the complex part. The larger the vent you have the more low frequencies “leak” out the vent, and the more power is needed from the aids to try and restore the lows. Smaller vent allows you to use a lower power receiver, and a larger vent needs more power. So perhaps there is some happy medium that works best. You do have most control of the vent size when you go to custom molds.

Prescription Formula - Phonak will have a proprietary formula which may work OK. Hard to predict without having the software to see what it will try to do. NAL-NL2 is the common industry standard. DSL v5 is another industry standard. When I compared the two, DSL v5 gives you more gain in the lower frequencies where you need it. Again I would have a discussion with the fitter to see what they think. My totally amateur opinion is that you may benefit from DSL v5 and it would be worth a try to compare to the other options.

Receiver Power - Again, needs to be discussed with the fitter. My thoughts would be a M receiver in your right ear, and P receiver in you left ear. But, it will depend on what venting is chosen.

I played with a few options in the Rexton software I have, and here is one that I thought might be worth considering. I used the DSL v5 formula and allowed the software to select the custom mold vent size. It picked a 2.5 medium size vent in right ear, and a bit smaller 2 mm in the left. In any case here is what it looks like.

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Reverse slopes aren’t well met by standard fitting algorithms.

I’d be inclined to try a semi-soft Acrylic with a selectavent option if there’s room.

Phonak/Sonova isn’t usually a good bet either as their inherent frequency shifting becomes obvious vs the HF that’s coming down the canal. Widex used to be the go-to, but as controllability is paramount I’d consider Oticon/Resound now. Allow the wearer to futz about with the graphic equaliser to improve the settings on the fly.

Usual complaints are background noise like tyre rumble or wind. Most manufacturers would stick a pile of mid and low frequency gain in, but for the wearer that probably wouldn’t sound right (echoing etc). My only other observation is that a volume control is essential (or a good app) especially in terms of dealing with auditory fatigue which is a potential issue with overpowering the lows.


Thanks. I am going to discuss the custom molds when I go in to get fitted for the ones that I’ve ordered. I thought they’d be counter-intuitive, but it sounds like they’re a viable option.

Phonak did tell them to only target certain frequencies because of (masking? bleeding? overpowering? Can’t recall) so that’s a better start than any other hearing process I’ve had. At least they aren’t starting out trying to fit like a normal person. I don’t think Costco sells the Oticon brand, but I’m pretty sure that they have Resound so I can try those if these don’t help. I was happy with my first Phonaks (2010 audeos, I think) and unhappy with the KS6 (Resound), but it could be because my hearing has deteriorated quite a bit and I didn’t have a very good fitter with the KS6.

Regardless, I want to be able to DIY program whatever I get. It’s an hour and a half to the nearest store and I ain’t got time for all that. Plus, I have a hard time articulating what isn’t working in a sound booth. At least the part where I tell them whether their changes are helping. I don’t want to have to continually go back to a fitter to tell them that whatever they did didn’t help me hear my soft spoken elderly boss.

If all else fails, I guess I will go see what the local audi has. It’s rural Iowa so I doubt they’ve seen many (any?) RSHL here. I feel like I’m on my own no matter how it goes. :rofl:

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My thoughts would be to try a semi-open fitting if you are going to go with an off the shelf fitting. If you consider the Rexton Adore Li aids that Costco has, the closed sleeves may work for you. They are a 1.6 mm equivalent vent. These aids have a special Own Voice Processing feature that helps with the occluding effect of more closed fittings. Here is what they would look like:

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Not being funny, but I think you might want to limit the advice in this respect. Physical occlusion is unlikely to be noticeable in that loss given the 500Hz level.

The ISVR in Southampton UK reverse modelled the effect of basilar membrane dead-spots and the resultant Audiograms. This audiogram has some of the characteristics of such a response.

If you look at the prescribed gain in the fittings above, you might be right, but it’s pretty much throwing darts in a room with no lights in terms of accuracy.

To the OP - the effect that you’re risking with overamplified lows is ‘the upward spread of masking’: essentially the amount of power (given the logarithmic plot) applied to lower octaves overstimulates the basilar membrane in adjacent higher frequencies and corrupts the signal from the better functioning hair cells.


At the end of the day a First Fit is a First Fit. You have to start somewhere and then listen to what the user of the hearing aid tells you they are hearing, or not hearing. I think one of the biggest issues in the hearing aid business is hearing aid fitters thinking they know what users are hearing, but they really don’t. There is a lot to be said for using trial and error to refine what the theory says.

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I can’t imagine a normal hearing person really being able to grasp that I can hear a wrapper being opened across the house, but I can’t hear the rumble of the train going by the house. True story, I had no idea that a train went by my newly purchased house until the first time my boyfriend came over and talked about how loud it was. :rofl:

Like I said above - the first fit you illustrate is wrong. Just look at the amount of gain shown in the left ear at 500Hz - the new user is used to speech (just) coming to them at threshold, but you’re punching it to around 100dB (65-70dB +30dB gain) on a whim without any form of Real-Ear-Measurement. So if the residual canal volume is lower than expected or you have a particular canal resonance there (I’m looking at you Oticon) you could be dumping in 100-105-115dB in around 500Hz.

People are probably thinking, OK, that’s not REALLY bad (it’s still in the same order), but you have to remember that these levels have approximately 500-1000 times more power than the level of the original loss. This is what leads to lots of head scratching and problems when the distortion caused by the upward spread of masking wipes over the good signals coming from the 3-8KHz area.


I can imagine. Mine is opposite though, deaf in the higher frequencies.
You are getting some really great help from Um-bongo. This ain’t his first rodeo!

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I think that’s why Phonak advised to only try to hit target at three frequencies. (I think it was 2k, 4k, and I can’t recall the third)

Thank you so much for jumping in on this thread.

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Yes, that makes sense, probably letting the aid roll off the low end automatically.


I am seeing normal level sounds/speech maxing out at about 90 dB in the ear at about 750 Hz in the right ear, and at about 95 dB in the right. Of course loud sounds are going to be about 10 dB louder in the ear. And of course REM needs to be used to verify that is what level is actually achieved. Unlike many practitioners, Costco is good at actually doing that. My main point is that all alternatives should be considered, and at the end of the day the user is the judge of how it sounds, not the fitter or the computer. Here is what I see with custom molds:

Yeah, I’d try the custom tips. With Costco, you don’t have a lot to lose anyway but time, right? The custom tip will block out the highs you are used to and they will need to be replaced artificially. But having more sound access around 1 kHz might be worth it to you in terms of intelligibility. If not, you can switch back to open domes. But as UmBongo already said, you probably will only want moderate low frequency gain and considerably more high frequency gain than the software wants to give you.

It would be interesting to see some ultra-high thresholds. Anecdotally, some of my RSHL patients have great hearing out to 20 kHz and others really only have an island of normal hearing from 4-8 kHz. I would guess that custom tips would be easier for the latter group.

With open domes and that hearing loss, I’d think you’d want to strongly consider secondary devices (e.g. Roger Select). That will be a problem with the KS9s though.