This worked for me as well. I wish I'd seen your post when I was trying to resolve my low volume issue, but I came here to tell people the same thing. I had read a different post about using a fine brush, dry, to clean the speaker where you would listen to a phone call. I had tried several times in the past and volume was still terrible. I made one final attempt but this time used my electric toothbrush. I gave it a full cycle from all angles. Whether it cleaned something I couldn't see, or vibrated a problem away, I don't know. But now my call volume is totally normal! It went from sounding so muffled and quiet I could barely here, and I was turning into one of those annoying people having to put it on speaker to even hear the caller. Now it is like new. So anyone with that problem try a toothbrush, it can solve the audio issue. My problem with low call volume on my iPhone X is solved.