Over the years, numerous times I have noticed my hearing deteriorating for one reason or another. In some cases my hearing is getting worse, but more often it is a problem with the aids (poor settings, clogged ear molds, etc). I currently have ReSound Lynx 3Ds. Conversations were becoming harder to understand. My audiogram showed no new loss of hearing. The hearing aids appeared to be going into compression even though I was in a quiet environment. It turns out the wire at the receiver end was chafing. I replaced both receivers and my hearing returned to normal. Here is how you can tell if this is happening to your aids. If you gently rub your finger over the wire connected to the receiver it sounds like you are brushing your finger across the microphone. A good connection doesn’t cause any sound when brushing your finger across the wire.
Another problem is the microphone getting plugged up. If you gently rub the case of the hearing aid and it is very loud and yet other sounds are soft or distorted, the microphone is working, the sound just has trouble getting into it. A good vacuum job on the mic openings with generally help clear things up.