Dont mute while cinematics or transmissions are on

[Phubar]

HI, i made a few transmissions an set cinematic mode on while playng transmissions in order to create a small intro. I set a background sound too (rain) an a random (i mean that it will play every random seconds between 5 and 25) sound of thunders but when the cinematic starts thunders sound will mute.

How can i made possible to continue playing even while cinematics and transmissions are on?