Thank you for the picture and Zebra for the db detail. With my initial Siemens aids I had domes similar to the Power Domes but with an air tube as the receiver was in the aid body. Only when I got the Phonak did I get receivers and wax guards.
In the first case I was just ‘given’ a pair of domes. Within a day one was very uncomfortable. I went back and got a smaller dome. Then the other ear, in comparison to the first, also became uncomfortable and a got a second smaller dome.
Then I got the Phonak and the audiologist provided the Power Dome 4.0S. These matched my hearing loss but after about 8 to 10 hours one ear again got sore. My audi then sent me the smallest vented dome and cautioned me to just use it on the sore ear.
Same again, the other ear now got sore, so, contrary to the audi instructions I fitted the vented to both aids. They are clearly less than ideal given my hearing loss but I can wear these aids for 16 hours straight (longest was 25 hours).
Bottom line, the best domes are worse than useless if you can’t wear them.
Supposedly open domes will provide greater feedback. If I cup a hand over my ear then I get feedback but I put comfort ahead of perfection.
If I put my fingers in my ears the HA behind my ears processes all the sound and feeds it to the receivers. If I then remove my fingers the ambient sound is a mix of direct path and HA processed sound. The volume is then lower. As I said, I put comfort first.
Yes, less feedback with a more closed dome, ASSUMING the same amount of gain. The more closed dome you have, the more gain you have without feedback, but if you keep increasing gain, you’ll get feedback. Feedback results from sound leaking out of the ears and reaching the hearing aids microphones, so unless one has a perfect seal (I doubt that is possible), apply enough gain and one will get feedback.