Comunication problems with moto t5420 HELP!!!!!!

Hi I recently buy a couple of t5420 they turn on the communicate each other only wen set to 0 the noise eliminator but the volume of the voice are tooooo low even with the volume set to max, the noise (white noise) sound perfectly luod but when I press the PTT the volume goes down
PLEASE HELP ME
SORRY FOR MY BAD ENGLISH:p