Hypothesis: custom molds optimize speech intelligibility for RIC w/ my audiogram

“Power Dome” is the product name. “Double dome” is just an informal description of the structure.

Here’s a pic of the pre-Marvel Phonak Power Dome:
https://www.amazon.com/Phonak-Smokey-Medium-Power-Domes/dp/B00DC8403A20
and of the Marvel, and, I presume, KS9 Power Dome:
https://www.amazon.com/Phonak-Medium-Power-Marvel-Hearing/dp/B07M5HP99W/30

I don’t know how up to date this document is, but see pages 4 and 6.

Phonak Tips and Tricks10

It would seem like the power domes have no vent at all, while the vented dome does have a vent but is not “open”. One would have to actually look at the Power Domes to see if they have a vent or not. The Rexton closed sleeves still actually have a vent which is said to be equivalent to a 1.6 mm vent.

They aren’t vented. The small hole in the center that the arrow is pointing to is the interior end of a sleeve into which the receiver fits. The photo is from Amazon but I took delivery of some a couple of hours ago.

Earlier this afternoon I happened to talk with a HIS at an independent dispenser and mentioned the apparent discrepancy in Target’s assumptions; she swore there was no way that a power dome would be more occlusive than a custom mold. But now I’m not so sure; as I previously said, my cShell mold is vented.

Note: this is the Marvel-compatible one; earlier power domes might be vented – I don’t know.

My experience with power domes or double domes is they seal pretty good but wouldn’t stay put. Even the ones that were too big and ended up hurting. I tried them all. Ended up getting soft silicone molds that seal properly and do not move.

Everyone is different, you just have to try them all out to see what works. Now if your hearing loss dictates needing molds, that is your only choice. A rule of thumb about molds is for those with a hearing loss of 40 dB or greater out to 2000 hertz frequency, you need ear molds.

Phonak has occlusion control settings that helped me when I first got ear molds. I bet other manufacturers also have similar technology.

Thanks, brec.
Yes that’s what I have while awaiting my custom Phonak SlimTips, although they look a lot more plump in that photo than they do on my receivers. They eliminated all feedback with my original setting and on standard receivers, but now that I have power receivers and my high frequencies kicked up as I requested, I get screeching whenever getting near a wall; hence the decision to switch to power receivers and custom molds.

Where/what are the occlusion control settings in Target?

A few comments. First I am not sure I like the term occlusion. That is more of a description of feeling plugged up, like wearing an ear plug. I believe the more correct way of talking about it is by the venting size. Yes, if you have no vent, you may very well feel occluded.

There are actually two reasons for reducing the size of the vent. One is if you have significant low frequency loss (which is not the case for @brec). This is when you need to restrict the loss of low frequency sound out the vent to let the receiver produce more bass. Not an issue in this case.

The more relevant issue here is with a significant loss in the 3-4 kHz range, and the associated gain to address it. If the fitting is open or the vent large then sound from the receiver gets back to the hearing aid mics and creates feedback. There are really only two ways to control it. One is to reduce the size of the vent, and the other is to reduce the gain. Obviously the latter has impacts on the benefit of the hearing aid.

On the “occlusion control” with Target/Phonak, their approach is kind of crude. All they do is attenuate the low frequencies. Signia/Rexton do it in a much more sophisticated manner. They are trained to recognize your own voice and only reduce gain when they “hear” your own voice.

The other choice here is what Phonak calls “vented domes”. I have not tried them in Target, but if the Power Domes are not tolerable, they may be an option. Not sure what the effective vent size is.

This is what I see with a Vented Dome and DSL v5. It may minimize required attenuation of gain some. Certainly better than an Open Dome.

This is the Slim Tip with the 1.2-1.6 vents. I am not sure why they give a range for the vent size? In any case it is certainly better than the Open Dome. A custom fit and optimum vent size is going to give you the best feedback protection and least feeling of occlusion.

As a last resort you could ask to try sound recover to get those highs down shifted in frequency, but I am not sure that is a good idea.

I would say that your basic hypothesis is correct. Reducing venting to an optimum level has benefits in optimizing gain in the higher frequencies, and also in rejecting low frequency noise. Both should improve speech intelligibility. Signia have written an article on it, see link below. Like all manufacturer sponsored articles however they have a sales angle, and that is to promote their Own Voice Processing as the best solution to the potential occlusion feeling a more closed fitting could cause. As mentioned before Phonak’s solution is not as sophisticated, but may work to some lesser degree if occlusion does become an issue.

The Trouble With Open - Signia15

@Neville said:

…

Sorry, @Neville, I haven’t yet become sophisticated enough to interpret that; perhaps you could provide an English translation?

On Monday, I arrived for my Costco Hearing appointment to pick up my silicone SlimTips which had been ordered for my KS9s. The fitter remarked something to the effect that “they want you to go back to the M receivers, but since the Power Receivers have enabled you to hear soft female voices, let’s see if we can make them work.” She went out and came back with my Power Receivers stuck into the new SlimTips and placed them in my ears. I was sitting down, the screeching near walls had stopped and I responded that I thought they felt OK and were working. I did all the shopping sitting on my scooter but by time I got to my car and stood up to get in I felt like one was falling out. All evening at home they kept falling out, especially when I spoke or ate dinner, so I was upset and discouraged and next day I immediately called and told her that when I experimented and removed the new SlimTips and inserted them into my ears without the Power Receivers and they fit like a glove in my canals but shoving the Power Receivers into the SlimTips naturally increased their outside diameter and made them keep falling out.
She urged me to come back in and I did so, at which point she suggested that “before having the molds remade let’s try going back to your previous M receivers, increase the gain and see how that works” which she did.
So far I am hearing my soft-voiced sig/other well and the feedback screeching is gone, but I am left wondering what if anything I am giving up going to the Ms with increased high frequency gain vs the Power Receivers with new molds made.
Any observations or suggestions would be very much appreciated. Can I or can I not expect performance with the Ms with increased gain to equal the hearing power of the Ps? I do like the feel and fit of the SlimTips of course with the Ms and so far I think I am hearing well. Later this week will be a further test as we will be having a family group in for a holiday visit.

This is what I am seeing in the Phonak Target 6.1 software. Assuming I am reading it correctly, it is showing that feeback is the limiting factor, not the power of the receiver. The dashed magenta line is the feedback threshold and it appears the software reduces gain to stay under the feedback limit. The light coloured curves are the Adaptive Phonak Digital target curves, and the heavy lines are the adjusted one. It is also defaults to use frequency compression (Sound Recover). So from what I am seeing you are not losing anything by using an M receiver.

Does that mean that the only reason I can still hear my soft-voiced high frequency Karen is because the new setting on these M receivers, and giving up my power receivers, is making her voice sound deeper? Not sure I would be keen on that as I have been looking forward to both hearing and understanding her normal voice.
And if you know, why did Phonak choose to make the SlimTips with the narrower inside diameter if they knew I was wearing Power receivers? I am only assuming they knew, as I was not furnished a copy of the order for the SlimTips sent to Phonak. In other words, was this step-down in receivers a deliberate decision by Phonak as a best practice, or only that they didn’t know I wore Power Receivers?

@NateS said:

Does that mean that the only reason I can still hear my soft-voiced high frequency Karen is because the new setting on these M receivers, and giving up my power receivers, is making her voice sound deeper?

I have only used the Target 6.1 a few times out of curiosity. I have KS8’s which use Connexx software. What I have noticed is that for virtually every audiogram I have tried the software defaults to use the frequency compression. It can be turned off of course.

On the size issue it seems to me that the fitter should be specifying what receiver will be used.

I see that I had previously put your audiogram into the Connexx software. It was with an M receiver and NAL-NL2. It does not show a feedback limitation with custom molds and a 2 mm vent. I have noticed that the Phonak feedback threshold seems much lower than the Rexton one. I know the Rexton one is somewhat optimistic on feedback. Perhaps the Phonak one is pessimistic. Here is what it looks like in Connexx. It shows getting up to 40 dB of gain without getting into feedback trouble. The Phonak software with the slim tips doesn’t even make it up to 30 dB.