Just recently, the sound coming through the earpiece on my 6S during phone calls, voicemail messages etc. has depreciated markedly in quality. it has got much quieter so that sometimes it is difficult to hear. I'm wondering whether this is something that has happened as a result of a software update, or whether it is a hardware problem. I know this can happen if, for example, the earpiece gets wet, but I can't think of when something like that could have happened. Everything else seems to be working fine. Does anyone have any thoughts? Before I take it back to the Apple Store, I would like to rule out anything simple, so anything in terms of diagnostics or ideas of what this might be would be very welcome. I've already tried the regular shutting down and restrating the iPhone, but nothing else. thanks in advance.