Costco KS10 (Phonak) custom ear mold options & info - my research

I was told by Costco in Sept. 2021 that custom ear molds are ordered from Westone (but at least at my store can not be ordered from Phonak). Westone as Mfg specializes in making molds and doess for many brands, however my focus is on KS10/Phonak. I have no affiliation with Westone or Costco.
If person through whom you are getting molds is very experienced/knowledgeable then below is probably not relevant to you.

OtoBlast is their silicone material option (see
This material additive is option that I might do: " e-Compound Additive
“e-Compound canal additive is designed to reduce feedback by diffusing reflected sound between the tip of the earpiece and the eardrum. e-Compound is available for all standard acrylic earpieces and can also be ordered in combination with the flex canal option.”

This finish option (rather than Matte, or Gloss) SlickSil is one I want:
" Slick-Sil® AM (Anti-Microbial) or silicone earpieces that is proven to be 99.9% effective* against bacteria, germs and other pathogens. As a result, Slick-Sil AM can be part of an aggressive infection control protocol. Slick-Sil AM produces a beautiful velvet finish that not only looks great but also helps with the insertion of silicone earpieces by providing a low friction surface finish. *Independent testing performed October 23, 2009 in compliance with JIS Z 2801 standards."

I do not know if there is additional cost for either of these options.

Acrylic material is also offered
In addition to the e-compound material additive noted above, the following can also be added …
Flex Canal
“Flex Canal is a body temperature-reactive, semisoft canal additive available on all standard Westone acrylic earpieces. The unique properties of this material allow the canal portion of the earpiece to remain firm at room temperature for ease of insertion and then soften at body temperature for increased comfort and seal. The flex canal option is also available in combination with the e-Compound canal option.”

Vent sizes
4 different sizes (1.0, 1.6, 2.0, & 2.4mm) are noted on Westone order form.
HOWEVER my understanding of Dr. Cliff’s rule of thumb vent size recommendation {} based on amount of DB loss is that for my audiogram a >2.4mm vent would be better, namely 3.5mm. Via Westone the only way I see to get larger vent size is to order molds with their SAV (Select-a-Vent) option {} which would have a maximum of 3.18mm.

Note that the maximum vent size that can be made for a mold depends on the ear impression and the overall diameter of mold as a limiting factor. Westone offers various styles/shapes of molds {}, and from what I see it seems that style 89 for Silicone offers the most real estate to accommodate a larger vent.

I am not a hearing professional, but prefer to be a knowledgeable consumer. I often find that professionals do not have the time to know about options that are available. While I will welcome the input and experience of Costco fitter who I will see tomorrow, I also want to know what is possible. I did call Westone directly and was able to confirm that a provider can pay a bit more for quicker than first class mail shipping, they were reluctant to talk to me about anything else once they knew I was not a provider. They indicated that it is typically 3-biz days from their receipt of order and ear impression to their giving the mold to the shipping vendor for return. Depending on where you live 14 calendar days might be cutting it tight if that is the interval you have between Costco testing appt. and pick up fitting of aids and molds. Definitely want the REM done with your new molds.

1st edit 9.30.21 to add: Commenter on this thread indicated that molds ordered via their Costco were from Phonak, so I conclude that each Costco HA dept is different with some only ordering from Westone (my Costco), some ordering from Phonak; and perhaps some using both or even another generic Mfg. I’d add that forum members have had success/preferred vent size that is significantly different from what the research articles suggest (and what Dr. Cliff summarizes as rule of thumb for vent size in a single chart).

1 Like

I have custom ear molds with no vents . Pretty much due to my loss. I’m not sure who makes who what material they are made from. I trust my audiologist to decide what’s the best mold for me. As long as they don’t hurt and I don’t get feedback I don’t really care. I’m more concerned with trying to hear .

Interesting. At my Costco, molds were ordered from Phonak. I suspect you’ll end up wanting smaller vents than 3.5mm. I started off with something like 3mm vents and ended up with something around 1mm. Too big of vents and feedback is very likely if trying to get much gain to the higher frequencies. Too small and one might have to deal with occlusion. From my experience there’s a fair amount of trial and error. I tried Phonak’s version of select a vent and was not happy as the plugs kept falling out. Maybe Westone is better at it than Phonak and you’ll have better luck

1 Like

Thanks for your exp. especially that Phonak version of Select-a-Vent kept falling out; if I do SAV will inquire about gluing it to prevent fall-out. I expect that rule-of-thumb chart in Dr. Cliff video is from this article about vent size {} and it in turn references research by Kuk F, Keenan D. How do vents affect hearing aid performance? Hearing Review . 2006;13(2): 34-42. It seems that larger vent size is suggested to reduce Occlusion Effect which some people do not tolerate well, and can be as much as 17DB of gain in hearing the lower frequencies of your own voice.

And as with many other things what is preferred/best for an individual person and their aids (as with you @MDB ) might differ considerably from the research. I expect that size and shape of ear canal play a significant part in what vent size works better for someone. Seems that most Mfgs claim that their noise cancellation should handle feedback from vent, but clearly that was not your experience.

It seems that with aid tech improvements, the art of designing/modifying molds has understandably taken a back seat to pursuing better hearing via algorithm tweaking.

1 Like

This statement would be better suited to domes, not so much with ear molds.

Ear molds are custom made to fit one person’s ear canal only, like a finger print. A person’s hearing loss defines the vent size based on acoustics. The feedback management and fitting algorithms are the fine tuners.

In my humble opinion.

1 Like

Good points. The part of my comment you quoted was my conjecture on why @MDB has chosen 1mm vent size after experiencing larger vents. He and I have audiogram with 20DB loss at 500hz which is frequency used by much of the research for suggesting vent size (in this case between 3 - 4mm; for your @Raudrive loss of about 55db @500hz that same chart would recommend 0.5 - 1mm vent size. So my speculation is that vent diameter and its influence on characteristics of frequency response interacts with the size and shape of ear canal (particularly from the tip of receiver to ear drum). My analogy from my audiophile listening days is that the ear canal is like the size and shape of listening room to which you have added reflective and/or sound deadening material and just like its impact depends in part on the particular room, the same sized vent in mold is going to interact with its “listening room” namely the ear canal.

TO drift a bit farther off topic: Perhaps you are someone else knows whether Target fitting software “suggests” that a custom mold be considered? and if it makes that suggestion whether it also suggests its vent size?

Again, thanks for your comment.

I can’t remember if Target recommends custom molds or not, but I’m pretty confident it will suggest a vent size. For me the challenge has always been getting enough gain at 3 and 4k without feedback.

Thanks @MDB; do you recall what vent size Target had suggested for you? Clearly quite a bit larger than what you have chosen as working better for you. {Sure sees like molds are another part of the HA realm that is a mixture of science/research and creative problem solving/experimentation.}

Sorry, I don’t specifically. I know the left was suggested bigger than the right–I think in the 3-4 mm range. Right, maybe around 2mm, but those are real rough guesses. If I remember it gives the recommendation as a range rather than a specific number. Yes, there are so many moving pieces. One is trying to strike a balance between occlusion, feedback and getting enough gain. Frequency lowering throws in another variable. (Basically if I want to hear anything at 4k or above, I need to use frequency lowering.) To me the idea that one goes in, gets fit with REM and is largely done is kind of a joke in that it depends on what kind of ear pieces are used and how much gain you can get at high frequencies. If occlusion bothered me and I needed an open fit, I likely couldn’t hear anything above 2500-3k without frequency lowering.




I have what turned out to be difficult to fit ear canals. When I got custom earmolds for my Phonak P70r it took 5 tries! Phonak could not get it right after 3 tries. Westone got close with the first set, and nailed the fit the second time around. These were silicon molds. With my small ear canals acrylic molds were apparently not an option.


Thanks @zuikoholic … since my intention with this thread is for it to be a resource around ear molds from Westone (via Costco) and not focused on ear molds specifically for me … perhaps there are some details you can add about whether there is more challenge in fitting you other than just small ear canal? what Phonak got “wrong?” What Westone did better at? And whether it was private audi, or Costco that you worked with. And perhaps most important whether differences in how the impression was done if more than one impression was tried that might have led to better success.

While my own limited ear mold experience has been fairly easy, and that very slight in the field modification/tweaking (grinding) was all that was needed on 1 of 4 molds I have had over the years, for you and others on this thread it is clear that having 1 or more entire re-makes of molds can be part of the process.

{While post shows 2 edits, there are no changes as I was attempting to edit my original post and clicked this one by mistake.}

1 Like

I am working through an Audiologist at a large teaching hospital healthcare organization.

In nearly every case the right ear has been the issue as the mold has not fit well and been very painful.

First we tried having Phonak remake the mold based on the initial impression, when that did not work we did another impression (with a different person doing the impression) with the same result.

With Westone the fit was good with the initial impression, but the left receiver would not stay put in the mold (it would work it’s way in and protrude past the inside of the mold in towards the ear canal) Westone remade the molds and the new set is working great.

Impressions were done the same way (as far as I can tell) all three times.


1 Like