Bought J7 in middle July. Many complaints from my friends I called about voice being distorted, under water, etc. Just replaced the phone Friday and same problem?? Both new phones?? Any ideas as Verizon is no help now.
I suggest that you follow the tech's suggestion. Also, you might want to try this: Go to Settings > Calls > look for noise suppressions, try to turn it off and see if it changes anything.
How's your network signal during those calls? Also, are you using a phone case? If you are, try to remove them. You should also check the mic if there's anything stuck in it.
I have samsung galaxy J7, but I don't have any sort of problem like this. It might be problem with your speakers.