iPhone12 IOS 15.6.1 Crackling When I use the phone

iPhone12 IOS 15.6.1 I have had the phone for several months. No problems. Last week it suddenly started making a crackling sound during my conversation that only I can hear. When it crackles, I cannot hear the other party. Other that this issue, the phone is fine. This happens with or without headphones.

I have restarted the phone, I have checked various settings. I have not installed any new product for months and I only use the phone for business.... so no games or apps that are not work related.

Any Ideas?