Power dome or open dome?


I think you’ve got this basically correct. I’ll hazard a guess that your increased clarity is related to additional high frequency gain retained as most manufacturer’s fitting algorithms way underfit the highs. That’s why to me it makes more sense to do REM and then work from there, but to each his own. Glad it’s working for you.


I did get REM done (a topic for discussion on the forum might be “What is a REM, actually?!” because there seems to be more than one way to do them in terms of how extensive the tests are, etc).

My audi said the REM results showed the actual fit (output) matched what Smart Fit wanted to achieve very well except the right ear at 4K was a little off and she didn’t think it was worth the effort of correcting that. So given that and the fitting software saying that I don’t need a change in gain at any frequency, I don’t think it’s worth going back to her just for switching from open to closed domes. Since I have a problem with little or no anti-tragus, I’m not sure that I could wear a custom mold. But after I see how smaller power domes and tulip domes work, I may go back for REMs for the dome/mold device of my choice as I suggested in my previous post. I don’t think I can hurt my hearing - the MPO (and lower input) settings hopefully prevent that - and if I have her REM approved settings to go back to and anything I do seems to improve my hearing, I don’t think that I can go far wrong. So REM doesn’t mean anything if you make a bad choice of domes, etc. REM would not detect interference between HA sound and sound that leaks through vents that distorts clarity. REM is just a one-dimensional measure of air pressure, not speech clarity.


To me, REM is fitting to NAL-NL2 prescription (or DSL-5) What I’m hearing you say is that the audi said you were close to what the (typically underfit) Smart Fit wanted to achieve.

What I’m trying to communicate is if you had REM to one of the established fitting formulas, you might find that you had the additional clarity you want with open domes and no occlusion. So the REM you had was with the initial “inexperienced” settings? I’m confident you’ll be able to achieve what you want with your approach–just seems backwards to me.


That is odd. It’s a 5 minute hook up and a few clicks


OTH, lots of DIY’s on this forum are apparently playing around and, AFAIK, not doing any REM’s. I think the main difference that we’re discussing here, open domes vs. closed domes, is not a gain issue but a likely interference issue. I actually seem to hear speech softer but much clearer with the closed domes. So I don’t think that increased gain is the basis of improved speech clarity. That’s the amazing thing - how clear the speech is for how relatively soft I perceive it.

I also think that if one believes the 2016 review paper that you cited on open vs. closed fit and the 2006 Widex technical paper that I added a link for in that thread, except for any annoyance with occlusion and some loss of sound directionality, a more closed fit will always be better for speech clarity than an open fit, no matter what the fitting algorithm and REM or not to go with the fitting algorithm. So what I’m mainly doing is deciding whether I like the occlusion, which type of occluding device is most comfortable, etc., before I worry about anything else.

The Smart Fit software does have NAL-NL2 and DSL-5 in it as programming options. So when I have time, I can fit my hearing loss with those algorithms and see if the resulting gain curves are significantly different from the Audiogram+ and also, when running under of either of those fitting algorithms, whether changing from open to closed domes makes any significant difference in the predicted, desirable gain output relative to the Experienced profile that I am currently running under. I’ll also see if I can find out what ReSound claims makes the Audiogram+ fitting algorithm different from NAL-NL2, etc. Surely they’d have something to say about this professionally to audi’s who might need convincing to deviate from NAL-NL2 in any significant way. So it would be instructive if that can be found out (but it might just be more whitepaper type fluff!).


Good luck getting any real info on the Smart Fit fitting. Manufacturers are notoriously secretive, but it is near universal that manufacturer’s encourage underfitting to increase acceptance. Basically what I’ve gotten from audis is that the manufacturer has studied this a lot and they know best. They probably do know best how to avoid the complaints of everything being too loud.


Domes are an easy less than a minute switch. I used to carry them and change them based on where I was going until I decided that in most cases there wasn’t enough difference to bother with it. But then I’ve never worn a fully open dome on both sides–only on the right. I did find that with the Oticon Alta2 Pro music from outside sources had a better bass than if I used a closed dome on the right side. And I use better in a relative sense as the Altas were lousy at music. I didn’t have a good music experience with HAs until the Evokes.


BTW, a really interesting aspect of fitting, that I learned about from reading the Starkey Compression Manual (discusses fitting in general) is the time constant for “attack” and for “relaxation” of compression.

(And, @Don, after reading the Starkey manual, I have concluded that fitting IS rocket science! There’s quite a bit of complex stuff to learn)

The most important lessons are that for speech intelligibility you want fast onset for compression and a fast recovery whereas for listening to music, you want a much slower onset and recovery.

What this basically means, I think, that if one wants to listen to music, everyone should use the music program provided for their HA. Using a general purpose program would not be as good an idea, since it probably has a fast attack/relax setting (can any HA automatically detect one is listening to music and switch to appropriate music settings?).

Sure enough, when I look in my ReSound Smart Fit settings, just as the Starkey manual explains, all my “speech” programs have a per syllable attack/relax time constant setting whereas for the Music program, the attack/relax constant is set to slow.

So the details might be too gory for everyone but DIY’ers but it sounds like besides having a Music program that is more linear with less compression, you want changed compression time constants, too, but I guess that automatically comes with everyone’s music program, as long as you’re actually using it!

Question about Static on Resound (Quattro) & Phonak (Marvel) aids

Ha, ha. Yep. If I had to master all that before making adjustments I’m sure I wouldn’t make it. Luckily the software does it for us. When I change the gain I notice it changes the compression ratio a little. I don’t see or know the details of that.

The way I think if it is, my pro and the software get it 90% there, and then I make very minor adjustments to fine tune the last 10%.


Hi, Mark

I think that one thing that’s pretty different between us is that I have much better low frequency hearing. So by my cockamamie interference theory and much less added gain added to my HA output in low frequencies, any sound that bypasses my vents is going to be closer in strength to the low frequency sound produced by my receivers. So maybe whether you are venting to any extent or not, the sound from your receivers will dominate. In my case, given the extreme openess of my open domes, I surmise that the amount of “outside” sound that gets to the vicinity of my HA’s is enough to cause problems mixing in with what’s coming from my receivers. I think it’s the 2006 Widex paper that’s cagey, allowing that outside sound could be in phase with your HA receiver sound or out-of-phase, causing some cancellation or distortion, depending on a particular individuals setup. So it’s probably one of those things where for an excuse for explaining things, I can throw in “everyone’s ears are different” (as probably are the acoustic properties of said ears when you start cramming various stuff into them!).


No doubt that everyone’s hearing is different and you do have much better hearing on the low end. I struggled with getting a good bass until I got the Evoke. And it was bass I was searching for when I was playing with the various domes.

Let me add that now that I have that bass I find that due to my lousy left ear I have to volume down a bit on that side when there is music with a heavy bass to mitigate distortion. :stuck_out_tongue_closed_eyes:


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/resound , 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.


Interestingly, the one problem that I haven’t had is anything coming out, even with the ReSound small power domes. Perhaps it’s because my audi thought the wires she initially fit me with were too long and has fitted me with wires that I actually think are a bit too short (so just like the domes, I wish there were a more in-between size!). Forget whether I’ve mentioned it but I think because I have little or no anti-tragus (the ear-buds-fall-out problem) that molds are not going to work for me, mainly for that reason.


The Precise Hearing website has good size info on domes for various HA’s, along with pictures. Has anyone dealt with this company and found them to be reliable, etc.? Their ReSound open vs. power dome dimensions agree with my “too big” medium closed dome experience. Hard to believe from the Phonak pictures, though, that all the different Phonak domes have the same relative dimensions for small, medium, and large!



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. . .



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.