Advices before purchasing titanium cShells / titanium earmolds

EDIT: This is continuation of my topic about my experiences with titanium cShells:

Titanium cShell vs. Power Domes – first impressions before complaining about large venting

I have experienced an unexpected turn of events in the last few days. My old power domes that I received with my Sphere 90 from Wholesalehearing.co.uk were pretty good, but have too much slit leakage to give me the proper gain above 2.5 kHz. There is my feedback threshold with that power domes, P receiver (DSL v5 Pediatric): [Przed zmianą na kopułki SDS 5.0 Zrzut ekranu 2025-08-20 002211] A few days ago I bought spare Phonak power domes, which has small difference on the appearance, but the …

END OF EDIT

DISCLAIMER: Titanium cShells are not a cure for anything. Please have mercy on your HCPs and don’t insist on titanium if you don’t have experience with acrylic earmolds/cShells (you used domes only) and you don’t have an allergy or a narrow ear canal, because in case of discomfort the waiting period for remake will be too long. Make sure you’re comfortable with acrylic/silicone ones previously.

I started thinking about titanium after VAST experiences with earlier acrylic ones before my decision about titanium (probably about 6-7 in the last 6 years, with trying different vent and receiver options).

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INDICATION:
The main indication for titanium is allergic reaction to acryl or silicone.
Another reason could be a small ear canal where a thinner cShell wall is required to fit the receiver and non-RIC BTE with silicone tubing (e.g. 13) is not an option.

My case:
I cannot get an UP receiver, because of its fitting range:

So I need P receiver placed as close to the eardrum as possible. It’s a little easier for me because I don’t feel the occlusion effect, so I can have no vent or only 0.6mm diameter. However, the occlusion effect should not be a problem for anyone if cShell reaches the bony part of the ear canal.

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SILICONE IMPRESSION:
I have quite large differences between open and closed jaw position (possibly 1-2mm difference, felt by my finger).

However the solution was:

1. Deep silicone impression. In my case I have it really a bit over 5mm past 2nd bend of ear canal.
2. Impression with closed jaw with not talking before silicone injection to its curation.
3. Second impression with jaw opened with 2.5cm bite block inserted before silicone injection until its removing.

To be fair, I probably have a pretty big ear canal. That makes it possible to place a significant portion of the deep cShell outside of the area of greatest mobility, which, IIRC, is between the 1st and 2nd bend of the ear canal. That’s probably why the feedback threshold is perfect in my case.

This may not be possible in patients with very small ear canals, however, the cShell manufacturer then should inform the Audiologist about technical anatomical difficulties. With S and M receivers the problem should be smaller.

Ideally (but not possible in every case), there is a few tips from Phonak for making deep earmold for Virtos:

(In my case, I didn’t encountered with EasyView Otoblock or Titanium FitGuide).

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ORDER FORM pitfalls:
ph-form-c-shell-6.0-8.5x11in-en-us.pdf.coredownload.inline.pdf8

1. Choose rough surface for extra retention (ERS).

2. I highly recommend writing specifically about wanting an extended plastic removal filament (with the ball at its end). The standard 5mm is too short in my case. 10 or even 15mm definitely makes removing cShell from the ear easier.
   

   
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3. Wire length - too long is detrimental to directionality because two microphones would not be aligned horizontally.

There is measuring piece as shown in the form, but I recommend measuring by rules written in PDF provided thanks to @raylock1:

Phonak SDS 6.0 receiver cable length differences

Here is a Phonak guide which may help. See the chart at the bottom of the page.

4. (I don’t tried it, consult that with your Audiologist): there is option to choose between Cerustop (standard) and HF4 wax filters. The latter is standard fo UP receivers. I don’t know if I can order P receiver with HF4 for theoretically better “acoustic reliability”:

The screens are mainly from:
Custom Product Reference Guide (New!)8

Feel free to ask me anything or correct me, if I am wrong!

IMPORTANT UPDATE:

I contacted with Phonak’s customer service recently and they stated that MINIMUM diameter of vent in titanium cShells are 1 mm, NO LESS.

So, no pressure vents like 0.5 mm or 0.8 mm.

IMPORTANT UPDATE:

I contacted with Phonak’s customer service recently and they stated that MINIMUM diameter of vent in titanium cShells are 1 mm, NO LESS.

So, no pressure vents like 0.5 mm or 0.8 mm.

I think their cShell order form is misleading because it doesn’t provide that information. If I’d known earlier, I would have ordered the cShell without a vent.

@Michael_Phonak, I don’t know if you have possibility to contact with proper Phonak “cShell department”, but there is some room for improvements.