Power dome or open dome?

Just a brief update on my “what type of dome vs. going to a custom mold experiment”.

For me ReSound medium power domes were too large, definitely larger than ReSound medium open vented domes. Pretty hard to remove from ear, gave a strong occluded feeling, could be uncomfortable when chewing, yawning, etc. Definitely improved speech recognition but lessened sense of sound directionality.

The ReSound small power domes are definitely a mm or two smaller than the medium vented domes. They are easy to insert and remove, give no sense of occlusion and I would say restore most but not quite all of the degree of spatial sound directionality lost with the occluding medium power domes. I would say that speech crispness, sensitivity is better than with the unvented domes, less than with fully occluding domes but maybe I’m at a relative sweet spot - need much more trial in a variety of environments to decide.

According to the UK site hearingdirect, the size of small power domes is 8 mm in diameter, medium 10, large 12. If anyone knows of a “power dome” from a different HA OEM likely to weigh in at 9 mm diameter and stay on a ReSound receiver, I would be much obliged to learn.

Would it be safe to say that dome fit on the receiver ought to work across the board for any major HA that uses Cerustop wax guards, as that consideration necessitates a certain inner diameter to the receiver nub a dome goes on?

Another question about domes is what type of material are they generally made out of. Can’t find ReSound stating for its domes but I presume the material is some sort of silicone compound. One of the reasons that I’m interested is to find out the approximate sound transmission/sound reflection properties by frequency for silicone material and thus by implications for domes. If anyone knows of a good table of sound properties of domes or dome material by frequency, I would also be much obliged for a link to that.

Looking at this https://advancedhearing.com/domes/resound22 , Phonak offers a 9mm power dome. Also, you might consider the Resound Tulip dome.

Thanks! I have the ReSound tulip domes on order but they’re coming from the U.K. per Amazon order (too lazy to make a 20-mile round trip to my audi to ask for them and not wanting to ding her for the cut-rate deal that I got on my Quattro’s through her via TruHearing).

Edit_Update: The link that you provided is great in that it actually gives compatibility with ReSound receivers AND the greatest outer diameter. Though if the diameters are correct (medium power dome = medium open dome), the apparent difference in use must be that vented domes, having less plastic, can squish, deform, conform to the fit of the ear canal better as you push in, drag out, whereas power domes, having more plastic, are stiffer and create more drag. I do think from attempting to measure dome diameters myself that the Hearing Direct measurements are more accurate (by 1-3 mm) than the figures Advanced Hearing provides, 7 mm for medium domes of either sort vs. Hearing Direct 8 mm for the medium vented, 10 mm for medium power. Don’t know if ReSound changed dome sizes at any point as the Hearing Direct site info seems a bit out-of-date, advertising “Currently only compatible with their latest ReSound ENYA and LiNX2 models.” (!!!)

I wore Resound tulips for years and loved them. They stayed in and I got no feedback and no occlusion.

@Don said:

I wore Resound tulips for years and loved them.

Called my audi about the Phonak dome fit. She too agreed with you and MDB that tulip domes were probably the best solution to me getting a close-to-an-occluding fit - she said that a tulip dome would conform better to an irregular shape in my ear canal at the endpoint of insertion than a closed, perfectly circular dome would and accomodate a wide variety of ear canal sizes. She also implied that domes were ~essentially interchangeable between all the latest hearing aid models but I didn’t pin her down on exactly what brands she was talking about - I know she fits Phonak’s and ReSound’s-so I imagine her assertion is most safely applied to brands that take Cerustop wax guards.

Edit_Update: (since I’m not allowed more than 3 consecutive posts!)

A bit further along in the dome testing here.

I got Phonak (Sonovos) Small Power Domes. The kicker is that they are actually about 1 mm larger than ReSound Medium Power Domes. But the Phonak dome material seems thinner, “softer,” and more flexible. So even though they are a teeny-eeny-weeny bit larger, they are actually more comfortable to insert and wear.

I get a sense of occlusion, voice louder, loss of spatial directionality ~same as ReSound Medium Power Domes but with much less pressure in ear and less noise when chewing, etc. Same crisper, clearer but lower volume sound effect when listening to speech.

The one thing that I don’t like is the little projecting loop above the receiver hole and no mesh inside the speaker hole to help prevent wax from getting into the receiver (although there is the wax guard mesh). Maybe the loop by itself will serve as an adequate wax barrier but it will be much harder to see if the receiver opening is clean (guess as 1BlueJay has done, I could always cut the loop off).

So I’ll keep wearing the Phonax domes for a few days and see how I like them but I think my preference right now would be to go with the ReSound Small Power Domes. They are almost occlusive, no sense of being in the ear, just a tad loss of spatial directionality, voices pretty crisp and clear compared to an open fit, easy to clean (because they are so small with less dome “flaps”), and they have the extra mesh guard at the receiver opening yet because they are so relatively small, they don’t plow up wax in the receiver area like larger domes do.

I tried the ReSound Tulip Domes. I’d say that they were actually the most uncomfortable of the lot (see below) because the hard receiver covering to support the tulip flaps is a relatively larger oblong shape. The trick for me to get them in my ear canals with minimum discomfort was to orient the tulip "petals’ so the bigger part of the oblong was down, the interface between the two flaps was horizontal. Perhaps because of the size of the hard plastic and the size of the tulip flaps, I had the most sense of anything in my ear and a sense of discomfort when chewing, yawning, etc. (I have small ear canals).

So my rank in ascending order for ReSound domes in terms of speech clarity would be:
Open < Small Power ~ Tulip < Medium Power with the Phonak Small Power in the same ballpark as the ReSound Medium’s

On wearing comfort and lack of consciousness of presence it would almost be the reverse, in ascending order
Tulip < Medium Power < Phonak Small Power < Small Power ~ Open Domes.

The Phonak domes fit nice and tight onto ReSound receivers.

You don’t mention whether you are re-running feedback tests in the SmartFit software as you change your domes. You may see changes in the gain possible at various frequencies based on how well the domes capture the sound in your ear canal vs. letting it leak out.

Also - while the ReSound tulip domes look like they are more of a closed fitting, we’ve been told that they are essentially an open fit in terms of how they work in the ear. . .

Chris

Hi, Chris

Thanks for the advice. I thought about feedback. Before I started switching domes and my user experience profile in the fitting software, I watched the ReSound video offered through Audiology Online on the theory and practice of using their DFS Ultra II feedback profiler. The video was a bit unhelpful in not really mentioning much about what circumstances merited running the feedback profiler again, seemed mainly to be called for in the advice given if the user was having a problem with feedback, if I remember correctly.

Since the feedback analysis was run for me while wearing open, vented domes and all the domes I’m trying beyond that are more closed, I shouldn’t have any increased problems with feedback going to a more closed dome - and that’s been my experience on trying each of the different ones that I mention for several days each.

I also did worry about changes in gain with changes in closeness of dome fitting as I mention in a post above in replying to MDB but in rerunning the ReSound Smart Fit 1.3 software and switching the hardware configuration between open domes and the closed power domes, the software did not refit me to any gain changes whereas if I changed my user experience profile, the software decidedly changes the amount of gain applied at various frequencies.

Below is a screen capture of my right ear fit showing the amount of gain applied with 50, 65, and 80 dB SPL of input (higher and higher series of red squares) for the OUTDOOR program, the one where gain applied most closely matches the fit prescribed for me by ReSound’s Audiogram+ fitting algorithm based on NAL-NL2. The darker gray inverse peak is the feedback danger region for me. The lighter gray region is the “Outside of Safe Fit” region and the red/pink region is “Outside of Instrument Capability” region" - so the diagram goes along with my experience - I have to try very hard to get any sort of feedback out of my instruments - I managed to get some the other day in switching back to the looser fitting smaller ReSound Power Domes, wearing closed over-the-ear headphones, and rubbing one headphone cup against my shoulder - perhaps the closed headphone efficiently traps sound exiting my ear in the vicinity of the HA mics and increases the chances for feedback?

So as mentioned in a post above, I’ve decided to go with the ReSound Small Power Domes. They are almost an occlusive fit but very comfortable. Speech clarity is pretty good. They are easy to insert and remove. After a lot of experience with these, I’ll worry about whether it’s worth the hassle and expense of a custom-fitted mold and maybe a decrease in hearing ability with (hopefully) further ageing will drive me in that direction anyway. The 2006 Widex paper analyzing an open fit vs. a closed fit purports to show from word recognition tests performed on a number of users that word recognition is just as good on a very slightly open fit as compared to a closed fit, declining by 25% to 33% with more and more open fits. So hopefully I’m still right in that sweet spot that seems to be offered by a little bit of openness. See figure from that technical article copied into my post in the “Article on Open Fit vs. Closed Fit” thread started by MDB back in 2017.

Article on open fit vs closed fit

In my own experience I’ve found several points about a closed fit to be worth more than any sense of occlusion: (from the 2016 review paper’s summary at end, on disadvantages of an open fit) “Second, the interaction of the direct and amplified sounds can cause audible artifacts and can lower subjective sound quality. Third, the benefit of adaptive features such as directional microphones or noise reduction algorithms can be decreased, and the available maximum gain before feedback is reduced.” …