iPhone 4 top front speaker producing little to no sound? Help!

So recently my reciever speaker (The one you hold up to your ear) Stopped producing sound, like there's sound but its almost impossible to hear anything. It's not just my phone either, my boyfriends 5C started to do the same thing. Has anyone else had this issue lately? We've both tried cleaning it out, restarting it, etc. Nothing. It's frustrating!