Background: Currently wearing Phonak V90s, with a custom mold cShell having AOV venting in the left and a Power Dome in the right. I’m expecting M90s in 9-11 days, which I will fit myself. I am going to try to maximize speech intelligibility. To that end I want to maximize available gain in the higher frequencies, therefore minimize feedback, and therefore maximize occlusion.
I wanted to try “de-venting” the cShell. What I did was cover the outer vent opening with duct tape. I would have done the same to the inner opening, just to avoid any residual sound passing through the outer piece, but I didn’t want to risk having to go the ER for extraction of a little piece of duct tape from my ear canal. As it turns out, the outer tape does the job quite well. Whereas previously I felt that the Power Dome was more occlusive than the (vented) cShell, now it’s obviously the reverse.
There are some aural (not physical) discomfort issues related to “head noises” with this degree of occlusion which I won’t detail right now, but I think I might adapt.
Here is the before (top) and after (bottom) with no changes except the roughly 8mm square of duct tape, and Target disabling the left “Use estimated vent” check box under the Feedback and real ear test result with the tooltip advisory that “Estimation of vent not possible with the measured feedback threshold or the client is below 10 years.” The solid magenta line is feedback threshold, the thicker blue lines are gains (80/65/50 dB) and the lighter blue lines are target gains for those levels.