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How to quantify a comparison molds to domes?

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What is the measure or measures that quantify the coupling effect using different molds?

so my question is how to quantify the coupling "power" or quality...comparing my vented molds to power domes to vented domes...and furthermore how to adjust that based on fit of the domes in the canal

(ie from the loose or open spots in the irregular canal shape. I can see with my camera that there's an area where the seal either open or at least not very tight)

Back story...I have worn acrylic slimtips for a few years with my Phonak Marvel aids. Parallel vent diameter 1.2 mm - 1.6mm according to my fitting report

All professionals have been telling me that I don't need molds based on my

The reasons I switched from open domes several years ago were

  • itch
  • insufficient headroom to get the volume that I wanted for the highs
  • better quality base, especially when streaming

Currently trialing Sennheiser Sonite Rise with EasyGuard power domes

I've struggled a bit finding the correct size for the domes and I still haven't trialed all the sizes that are an approximate fit to find the best possibility.

I currently have a medium on the left and a S/M on the right. Medium feels a bit too 'full' on the right and was initially giving me some discomfort.

I've also tried easyguard vented domes size medium. Smalls are obviously too small, they don't even seal....

I've had more itch with the domes but otherwise it's been a decent experience. I feel like the itch is almost in-check now that I've downsized the right.

I still wonder though if the medium vented Easyguard domes might be a slightly better fit because they are a slightly smaller diameter. I could be wrong but I don't think that the itch is an alergic reaction. Instead I think it's just the nature of having an elastomer rubbing on sensitive skin. The fit of a round dome into a whole with an irregular cross-sectional shape will naturally give tighter spots and looser spots around the circumference, and since it's not locked into place it will certainly move around...leading to friction and itch.

I really need more highs and lows, though....so I'm assuming that I need a more closed coupling.

and I just switched back to my Marvels with the molds for a couple hours this morning. The molds are certainly less comfortable. No itch but I can definitely tell that something is in there. It's a full feeling. Not painfull really, I just know taht they are there all the time. Not about the occlusion so much; I think it's more to do with the internal all-around pressure. I feel it with domes too, but not as 'bad'.

It's the only set of molds I've ever had so I have no idea if these are a good fit or not. My old audiologist did the fitting for them....

So, I really want to continue to try and give domes a good chance.

I need to wait for my follow-up visit with the Costco fitter to see how much more headroom they have for highs and lows in some of these program modes.

thanks

9 people in this conversation13 min readJump to latest

adding to my ramble..... just for context

my mind is racing around comparing my slimtips with a defined vent size vs power domes with no vent but a leak around the perimeter vs vented domes with a vent + the perimeter leak vs the old style power or vented domes vs I don't know what.... maybe a looser-fitting mold or a mold with a bigger vent based on my , etc.

The shortest, and possibly roughest and/or incomplete, answer is running a feedback manager. I have done this with different ear tips as an early indicator of how much room I have with a particular size or shape of dome (or earmold).

The longer answer is real ear measurement. The cartoon of hearing aid fitting software can show you arbitrary gain amounts for certain bands, but even similar gain amounts as shown in the software can yield significantly different levels at the eardrum.

As far as "needing" earmolds versus domes, the real answer is that both have their advantages and disadvantages. Although a general rule is to favor domes for more mild losses, factors like itchiness, retention, dexterity, etc. are all completely valid when going one way or the other.

Your provider could do on the old ones with slimtips and the new ones with domes and see if they can hit the high frequency targets equally with both.

I haven't done it yet but plan to try putting the slimtips onto these Sennheisers soon. The receivers look to be about the same size and shape. I think they'll work...

Another way to ask the question, is the coupling measured in any particular units?

such as the way hearing protection is specified with an NRC value?

for example, how would I put a number to quantify the performance level

my slimtips with their vent are ? times the NRC vs Easyguard power domes

or Easyguard power domes vs Easyguard power domes

etc...

In reply to @bradw

They'll fit. But keep in mind that hearing aids are programmed to the specific coupling, so when you change domes, and change venting particularly, they should be reprogrammed. So if you switch and things get boomy or sharp or thin, that may be the reason.

In reply to @bradw

@bradw said:

Another way to ask the question, is the coupling measured in any particular units?

In the useful parameter is Real-Ear Occluded Response/Gain (/REOG).

IIRC, it measures "earplug effect".

Look at mine REOG (lower curve) with Unitron power domes:

REOGHigher curve is REUG (Real-Ear Unaided Gain), so what gain is provided by bare characteristics of my ear canal without any .

Why not go with the EasyGuard Power in medium but cut a slit down one side of the dome with snips to take the radial pressure off the canal.

I have various aids, and have used:

  1. Deep Custom Mo(u)lds (3mm vent)
  2. Acrylic Slimtips (1.6mm vent)
  3. Power Domes
  4. Closed Domes

1 & 2 work best for me, as I can get decent volumes, and clearer speech, without occlusion

3 - I hated them. I hate occlusion

4 - I find these comfortable, but the feedback manager just removes too much gain where I need it. Also, others sitting close to me can hear their own voices coming out of my head :joy:

Peter

In reply to @Neville

thanks. I did know that this was a setting, and found it interesting that when I went back the day after my fitting, looking for a different dome size, the clinic manager (AUD) swapped out the EasyGuard power domes for EasyGuard vented domes, and didn't adjust the program.

I was already getting a little feedback and that was one of the issues that I had told her in the interaction and as far as I know she didn't address it...only noting it for the followup appintment later. Anyway, the vented dome might have made for a little more feedback...maybe. It honestly wasn't overly different and that's one reason my mind was going down this path to quantify the coupling seal.

I mean a round power dome in an ear canal that has an irregular cross-sectional shape is vented anyway, so that little tiny hole doesn't change that much.... and that thought has me going down the path of wondering how to verify that the coupling seal is "good enough" and comparing vented domes to power domes to molds and all of them against what I "need"...or what is "good enough"

In reply to @Bimodal_user

good stuff for research, thanks!

so if I understand just based on the definition that google is giving me, Real-Ear Occluded Response () would be relatable to the NRC that I'm familiar with regarding ear protection, REOR being in for specific freqs while NTRC is a ratio of total absorption

why are your two lines diverging for the left but so close together for the right? Is your right an open dome fitting and your left with the domes?

Anyway, for my purposes I think that I'm getting form this that while I'm experimenting with the different types and sizes of domes to find the most comfortable option that still works.... the still works question need to be answered through the REOR/REOG response curve measurement....so they probably need to run taht curve with teh two or three bast fitting dome combinations, to see which gives the best acoustic fit....

In reply to @PeterH

@PeterH said:

4 - I find these comfortable, but the feedback manager just removes too much gain where I need it. Also, others sitting close to me can hear their own voices coming out of my head

yes, this what I think that I'm experiencing, exactly!!

and it's in big part why I asked to try the slimtips to begin with.

My daughter has heard my aids many times during this Sennheiser dome trial..and from quite a big distance away too!

I'm really wondering if there's a way to get a molded slimtip or some other style, that's maybe a little more open (with a bigger vent) and a little more comfortable than my previous set. I think I mentioned before, but those are the only ones I've ever had so I have nothing to compare them against and really have no idea if the are fit well or not. Comfort is just ok. The occlusion is there & I've often wondered if they are deep enough...but it's also not bad I suppose...ok enough for me to live with it for several years now.... Also, They are HARD and I can pretty much 100% always tell that I have something hard in my ears. Except for the occasional itch the domes are more comfortable than the molds I have

In reply to @bradw

@bradw said:

why are your two lines diverging for the left but so close together for the right? Is your right an open dome fitting and your left with the domes?

Don't bother with it, my left ear is ear. There wasn't any measurement in it.

@bradw said:

the still works question need to be answered through the REOR/REOG response curve measurement....so they probably need to run taht curve with teh two or three bast fitting dome combinations, to see which gives the best acoustic fit....

REOG/ isn't sufficient for assessing "the best fit". The most important is which determines whether the is achieving its amplification targets.

In reply to @bradw

@bradw said:

I'm really wondering if there's a way to get a molded slimtip or some other style, that's maybe a little more open (with a bigger vent) and a little more comfortable than my previous set.

Maybe and maybe. Hollow slimtip is less occluding than solid and you can ask for more venting and phonak will accommodate if the ear is big enough. Could possibly try an open or moving jaw impression to improve comfort, or taper the tip a bit more--it's useful for the clinician to know where the discomfort is.

In reply to @bradw

@bradw said:

I'm really wondering if there's a way to get a molded slimtip or some other style, that's maybe a little more open (with a bigger vent) and a little more comfortable than my previous set. I think I mentioned before

Slimtip is convenient when it comes to change receiver, but it may not have such an optimized receiver position as cShell, because with the latter, manufacturer has greater flexibility in the design of.

In reply to @Neville

@Neville said:

Maybe and maybe. Hollow slimtip is less occluding than solid and you can ask for more venting and phonak will accommodate if the ear is big enough. Could possibly try an open or moving jaw impression to improve comfort, or taper the tip a bit more--it's useful for the clinician to know where the discomfort is.

The one I have is hollow. I'm fuzzy on the process since it's been a few years, but the way I remember it she has me slowly open and close while the mold media was setting up. And yeah I can understadn that it would be helpful for them to know that...knowing me I'm sure I provided all the detail that I could... the second third of the equation is a clinician that knows, and the third-third is a clinician that tries. I'm not saying that she didn't know or didn't try.... I just really don't know....

In reply to @Bimodal_user

@Bimodal_user said:

Slimtip is convenient when it comes to change receiver, but it may not have such an optimized receiver position as cShell, because with the latter, manufacturer has greater flexibility in the design of.

now this is something I've wondered about for years. I've never gotten the sense that either of the fitters (my prev AUD or the Costco tech now) have actually measured or really evaluated the position and orientation of the receiver

is it deep enough or too deep?

is it aimed in the correct direction?

is the seal and vent size correct?

etc....

Even though I ask a lot of questions, in the end they are just sharing only as much as they want to, so I really don't know everything that they thinking, what they are looking at and doing. I assume that some of these questions are answered either directly or indirectly with some of the and feedback tests that they run.... but are they doing everything? are the results optimal or just good enough? etc...

It seems like the c-shell could be an expensive headache. Ok if it's really needed, but probably not worth it otherwise.... I've had to replace the receivers too often in my 7 years of wearing these aids for me to think that special ordering a custom thing everytime makes good sense unless it's really needed

Does Costco offer acrylic cShells (I know it doesn't offer titanium)? If so, $40 a mold and remakes if needed is as cheap as it will get absent insurance paying most of the cost.

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