Questions about Earmold Types and Venting to Reduce Feedback


Don, could you tell me a little more about select a vent and would they work with phonak hearing aids?



I have Phonak. I call it select-a-vent because to me that is the most descriptive, but every lab has their own version and name. I know the Rexton lab, the Phonak lab, and Westone have that. I think it might be Westone that actually calls it that.

Select-a-vent is a relatively large vent hole in custom molds, and included are a number of inserts that have holes in them of different sizes. Think of it like this, say you have a tube and a doughnut fits perfectly in the tube. The doughnut has a hole in the middle of it. Now say you have a whole selection of doughnuts, each with a different size hole in the middle. So you can select how big you want the tube opening by selecting the doughnut with that size hole in the middle. There is even one doughnut with no hole in it.

Your pro will be familiar with it and know how to order it.

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Those Memory Foam Earbuds looked interesting to me unless you said “gently pressing them into my ear canals probably eight or ten times a day.”
Did you mean that they keep slipping out during the day and you have to keep pushing them back in?
Or am I misunderstanding you?



I have a conductive loss so require a lot of power. I also wear Phonak UP hearing aids. Target recommend 0.8mm vents but I wear 1.2mm vents. It works really well as I get no feedback at all.



I suppose that is possible. I have been tested in the clinic and I have done it at home with headphones. Nether showed no hearing, but you never know for sure I guess. The other issue is that I might be able to hear those frequencies when supplied with 90 dB tones, but what happens to the sound when I get 110 dB or higher? Don’t know. I suppose they could then start to distort.



I am totally new to the earmold thing. About all I know I have learned here or by reading this somewhat dated (2006) Tutuorial on Earmolds. This is what they said about the shape of the mold.

“The sound escaping from the ear canal always follows the shortest path to the aid’s microphone. This path runs along the canal wall (commonly the front wall), above the tragus, and straight toward the hearing aid microphone. A larger earmold concha, an extended helix, or a raised tragus will not prevent acoustic feedback because the concha, helix, and tragus do not contribute to the earmold seal. They are simply not in the path of the leaking sound. Although the tragus area seems to provide additional seal, in reality it does not because the tragus forms a protrusion over the line of the head, and the leaking sound escapes sideways. The practice of fitting full-concha earmolds to prevent feedback should be reconsidered unless earmold retention or patient dexterity is an issue.”

Edit: I see this is a multi part article and I should read the other parts…



I have moderately severe hearing loss and wear ITE aids, my left aid has .8 vent and my right aid did until my Audi reduced the vent in my right aid to almost nothing. I can still force the smallest cleaning thing through it.



It seems to me that at some point a vent becomes so small that the acoustic impact is negligible, and it only serves the purpose of pressure equalization on each side?



The Audi did my aid so I wouldn’t have the feedback issues that I was getting with the higher volume I needed.



I read an article about a month ago about domes, molds and different sized tubing using the same hearing aid. It was in 09 I believe. Sorry, don’t have the link right now. It used a type of REM to measure sound with different acoustic set ups, very scientific. Each measurement was at different frequencies. The results were very clear as to the better the ear canal seal and the larger sound tube were superior. The point being made with your RIC aids is the seal to your ear canals. Earmolds would be superior.
I am surprised you are having feedback issues with those modern aids.



To date I have only tried vented and closed off the shelf click sleeves. I am scheduled to be fitted for an earmold this coming week. I just want to be sure I ask for the right design features to minimize the risk of acoustic feedback.



Do a google search for earmold types.
Knowing all the different types and materials will help you talk to your audiologist. I don’t think your loss will not need a full shell or even a half shell. Something more discreet should do well.



In doing a search in Canada for earmold manufacturers I found this one called OTO Hearing Products in British Columbia. It lists Costco as one of their suppliers, so my guess is that is where Costco will have mine made. This is their Earmold Style and Materials Guide. I am thinking about asking for the #4 Canal Lock style, and the #8 True Tip material, which is a combination of their Medi Sil for the exterior part, and the softer Medi Sil II for the canal portion. This seems to be their Vent Options. Not so sure what I should be asking for there… They don’t seem to have the Select-a-Vent option, although they talk about a SAV plug. Again not sure what that is…

Edit. Did a google on SAV and that seems to be a Select-a-Vent term. Perhaps that is the one to pick?



To minimize risk of feedback, smallest vent possible and a good seal. I think I’ve read that silicon provides the best seal (makes sense to me as it’s got some give) I wish we’d get somebody like @Neville to comment on the likely benefit of trying to amplify the frequencies of 4k on up in your left ear.

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He actually sent me a few PM’s a while back when I first got here and was asking about using the SmartFit formulas. He recommended using the NAL-NL2 or possibly the DSL v5 for more highs.

Cutting back gain in the 4 kHz range certainly does give some relief from the feedback, and that is where I am at now.



I just don’t think you there’s much to gain by trying to cram more gain into those higher frequencies. I think you run the risk of masking lower frequencies for little benefit, but, it’s essentially boils down to trial and error. Good luck.



What vent size does your hearing aid software recommend with an ear mold? The smallest vent without occlusion is best usually.
See what ear mold your audiologist recommends. You now have a knowledge to compare notes with them.
A different size receiver may help that bad ear???
Yep, the pro’s chiming in now would be nice. It is the weekend.



With select-a-vent you can pick the vent that works best, even using different vents for different situations.



They work fine just leaving them alone. They do slip out some. If I push them in I can put my hands over my ears and get no feedback at all. Generally I leave them alone. I suppose I could wash them and ream out my ears with a wash cloth but I don’t do that.



The Connexx soft ware says Click Mold Short 1.3 mm for the left, and 2.5 mm = medium SAV for the right. I think that means select a vent for the right but not for the left. Perhaps 1.3 mm in their software is too small for SAV.

As for receiver, I am on the M type now. The S was marginal, but the M should not be…