When I am talking to someone on the phone, its hard to hear them

Firstly make sure your speaker mesh on the earpeice is not blocked if you take a look under a magnifying glass you can normally see it's clogged up.

If so clean with a fine pin and don't push to far down or you go right through to the speaker and damage it.

Then look at the bottom of the phone and check if you have the same problem and clean.

Secondly rule out firmware bit could be a bug in the software.

Back up your device and the activate without putting you backup on and see if that helps.

Thirdly if none of the above options work.

You make have a board issue.

Cheers