Hello if anyone else is still having this problem and it started around the time iOS 12 was released or you purchased the phone sometime after one of the updates added a feature for iOS devices that support surround features for the audio if you go into your settings>general>accessibility and scroll down to the audio section you’ll see an option that says mono if this is turned off this could be your problem. Just turn mono on and it’s a night and day difference. In the past I’ve tried cleaning the earpiece and nothing worked so I started looking at the settings and noticed I now don’t have a scroll bar for call volume and a few new options were there that weren’t before like the option for Bluetooth hearing aids. My issue with mine didn’t start till after an iOS update and so I looked for any settings that could be causing it. Naturally I’ve already tried cleaning the mesh over the earpiece and had already considered replacing the earpiece speaker all together but I didn’t think that’s where the issue was coming from as there was still sound coming from it however quiet. And before you ask no My hearing is fine and usually I have to turn down call volume really low because of how loud it is so this being an overnight change was pretty strange to me. Anyway hope this helps for anyone still having this issue. To me it shouldn’t be too hard to fix the update so that it can have separate settings for both speakers but I think that’s kind of the point considering apples past. Wouldn’t surprise me to find out they turned off a feature by default so you would think your phone is broken and have to buy a new one