Bluetooth Mic Audio Really Bad

Mar 17, 2016
Hi to all! I've buyed this wonderful phone and flashed 7.1.3 stable and it works fine... but.. The audio quality of microphone of my bluetooth headset (plantronics m70) is really bad! With my old nokia ( with windows mobile 10 ) quality is pretty good.. I think it could be some denoise settings in MIUI or android, but i couldn't find any menu to set this.. Coukd anybody help me? Thx :)