sound issue (interfering sound)

So i run 3 cdj 2000 nexus 2 and djm 900 nexus. All connected to my pc and running through rekordbox performance also using djm as soundcard on rekordbox but when i am djing i am getting a sound cutting in and out over the music. kinda like in the old days when u had your phone to close to speakers and it would go off when u get a texted ? how do i fix this ?.