@Motty2012: If you have a case or cover on the phone, please try removing it to see if this helps. If not, or if this isn't applicable, then head to the Samsung Members app > Press and hold on the app icon > Diagnostics > Mic, and follow the on screen instructions. Are you able to hear yourself clearly in the playback? Similarly, head over to your dial pad and type in *#0283#, then select “Start: RCV_1stMic” and speak into your phone like you’re on a call. Can you hear yourself talk?