I went from a 5S to the 6S Plus, and calls sound strange - I'm wondering if there's something wrong with my phone? I thought I was holding it wrong but I keep moving it around and calls just don't sound clear at all - they sound muffled and like I'm talking through a tunnel. Anyone else having an issue like this, or have any suggestions for what I might be doing wrong? I do have a tempered glass screen protector and can confirm that it's not covering the speaker.