Speaking as an experienced American dispenser who fits a lot of Phonak, the problem isn’t with the slim tubes themselves, it’s more with the acoustic coupler (mold, dome, etc). The Naida family was never envisioned to be fit open and in the world of fitting and audiology, that either means a slim tube or having the receiver in the ear with an open dome on it. Since the Naida was never intended to be fit this way, it’s logical that Phonak would not have it that way in their software, even though tubing these days doesn’t make the same difference it did in the days of analog aids when you didn’t have that much control over the aid. If you have the proper mold on the end of the slim tube, there is no reason one could not use this type of fitting on even an UP Naida and get not only a discreet fitting, but the frequency response you need to compensate for the kinds of profound losses these aids were designed to handle.
In terms of the molds themselves, a slim tip could work provided it had no vent. However, most earmold manufacturers in the US will make slim tube molds (often called receiver molds) in the different styles (half shell, full shell, canal, etc) with or without venting that will properly couple the tube to the ear. Very often for a truly profound case, I won’t use a vent because it will cause the aid to feed back when it gets the kind of power that’s needed – I can use the occlusion control in the software to compensate for the lack of a vent. Further, I just tell the aid that it’s a standard tube with a standard mold that’s occluded and it takes it from there. Yes I am lying to the hearing aid about what it’s tied to, but it doesn’t know the difference and my patient hears the same thing, so what’s the foul?
