One problem might be that I’m assuming that ReSound Preza’s work just the same way ReSound Quattro’s do with Smart 3D and so on. So that might be a cause of differences in observations between us.
Just to illustrate the extreme difference in feedback that’s possible between an open dome vs. a mold with very little venting, I’m posting a fitting diagram that I have for the same ear with open dome on left, occlusive mold on the right and the grayish mountains coming down from the red regions at the top indicate inversely (top to bottom) increasing sensitivity to feedback as determined by a feedback test that your HCP can do. You can see with the much bigger gray area coming down with the open dome on the left, if I wore that, my ear would be much more sensitive to feedback (if you amplify up into any of the gray area, the HA’s will produce feedback). The fact that the graph on the right just has a small hill coming down indicates the ear will now be relatively immune to feedback. That allows input sounds to my ear to be amplified more up towards the top of the graph wearing the mold and a more aggressive amplification program is being used in the graph on the right as you can see the dotted lines can rise higher up without danger of entering a “gray mountain” feedback potential region. Wearing a more occlusive fit is not without its cost - there is the “sound of your own voice” problem that a lot of people don’t like but just like everything else, you can adjust to it and I much enjoy wearing molds for their other advantages.
Theoretically, your HCP could show you this very same diagram for your ears and explain how sensitive you might be to feedback with the domes you’re wearing. When I visit my audi, she has her fitting screen arranged in a way that I can see everything on it and she’s very willing to answer any question I want to ask her about my fit and how hearing aids work. So since it sounds like you have a great HCP, too, maybe he could do the same for you if you think it will help you understand what’s going on with your HA’s.
You might ask your HCP whether he’s set you up in the ReSound experience profile as a “First-Time User” or as “Experienced User(Nonlinear)” - and if not the latter, you might ask him if you could try that user experience profile. You get more amplification and I can hear speech a LOT better with it (plus the molds). Part of the greater amplification on the right is the switch from First-Time User to Experienced User (Nonlinear) and another part is using the NAL-NL2 fitting algorithm as opposed to ReSound’s proprietary Audiogram+ (which ReSound claims most users prefer over NAL-NL2-but I don’t). If you were willing to temporarily sacrifice one of the four programs (Restaurant?, Outdoors?), your HCP could even put one user profile/one fitting profile is as one version of the All-Around program and another version of the All-Around program in in place of, say, the Outdoors program with a different user experience profile and/or fitting algorithm and you could switch back and forth between the programs and see what fit you liked best - then go back to using all the regular programs adjusted for the experience profile, the fitting algorithm that you think worked best for you. I think this great idea was suggested quite a while ago by Neville to Volusiano in an Opn1 thread and I tried it myself to decide that I liked the Experienced User (Nonlinear) user profile with the NAL-NL2 fitting algorithm best. But your HCP could discuss the possible differences you might experience switching around like this and whether Costco’s fitting policy allows you to play around “creatively” like this. It could be a big waste of your time and his and it’s really only for folks that are keenly interested in tuning their fit to the umpteenth degree and have very understanding HCP’s who are willing to humor them!
P.S. The graphs show the amount of gain in dB being applied to soft, moderate, and loud sounds across the frequency spectrum for the parameters in play with the right ear (“red is right”). Perhaps somewhat counterintuitively, though, soft sounds are the highest curve, moderate the intermediate, and loud sounds the lowest. So basically, the curve shows that soft sounds are amplified much more for me in the right curve than the left. Since soft speech sounds of my soft-spoken wife are what I want to hear better, the right fitting parameters work a lot better for me. For anyone else, YMMV. Loud sounds are not being amplified at all, either, for either fitting algorithm. The HA is just replaying them into the ear at the same loudness the mics hear them.
But Resound knows even more.
