How to choose a dome size -- diameter?

Hearing Aids
#1

For a given kind of dome, how would a fitter choose the size – S/M/L or, for some brands, diameter in millimeters? Over the years I’ve not encountered any kind of measuring tool. Is it just an estimate based on an otoscope view of the canal? Or is it trial-and-error based on what’s comfortable for the user?

Is the ideal size one in which the circumference of the dome just touches the ear canal, or is it a bit smaller, or is it a bit larger in which there is a circular “flap” that lies against the circumference of the canal? Maybe another way to put the question is how much venting should there be, if any, between the edge of the dome and the canal?

#2

I think it’s more trial & error. Also, I think the Phonak silicone power domes come in S/M and L - just those 2 sizes.

There are times when one ear canal is a bit more swollen when I wake up than the other, and I’ve had to swap in a smaller S/M dome on the tip. But most times, I do fine with a L dome on each tip.

The ideal fit will keep feedback from happening when you place your hand (or phone) up to your ear.

#3

This provider blog entry provides some good information.

The link goes to this sentence, with some additional guidance in the paragraphs that follow it.

The dome should be slightly larger than the patient’s ear canal to seal the ear canal, but there shouldn’t be too much pressure on the ear’s skin. This will cause discomfort and redness to the ear. A dome that fits perfectly should make a light rustling noise when it’s inserted or removed.