Galaxy S9 poor call quality

[Android Central Question]

I've had my S9 for about 3 months now, and I have found recently that I am having trouble hearing others clearly when I make calls. The sound will be muffled and/or distorted on my end. I have trouble believing it's bad coverage, since I will be in areas I never had problems before and likewise for people I'm calling

 

[B. Diddy]

Welcome to Android Central! Are they also muffled if you use speakerphone, or a wired or Bluetooth headset?