Iphone 7 sounds muffled
I upgraded to Iphone 7 from 6. When I am using the speaker on phone calls it is muffled. It doesn't matter if I have a case on or not the call quality to the other person is severely muffled on speaker. Without the speaker on, they said it is clearer. Is there a way to fix that or is it problem with the phone?
iPhone 7, iOS 10.0.2