When I look at the calibration of my HA’s they only vaguely resemble my audiogram. Apparently, a lot of optimizations have taken place to allow for the best understanding of human speech. Even the music program does a lot more than just inverting your audiogram to compensate. However, it does resemble it a bit more.
Obviously, I would like to hear others pitch in with their experiences. But I normally just use the Phonak Target frequencies values for lowest dB band in the equalizer and save the setting profile as Phonak Target. You could also just compensate for your hearing loss and set the negative values of your audiogram into the equalizer as positive values and save that profile as audiogram.
So the program I need is Phonak Target and a music player with an equalizer that allows me to save the profile. Depending on your aids, you would only need your HA’s programming software and enter your audiogram and generate a music program for your HA’s. And a equalizer with profile saves, of course.
You could just make a program on your HA’s that completely suppresses feedback. My mother use her’s all the time and her high frequencies audiogram has >-100dB losses.
If you have open domes that might be harder, so you could make a plug that stops sound coming out of your earcanals while the HA’s are in. Probably that is the solution you want anyway. I’ve heard people use eraser, but I would probably use 2-component silicon paste.