Windows 7 Flight Simulator X with no Air Traffic Control sound

[windows7]

I have installed Microsoft Flight Simulator X everything goes well and the game runs normal but there is no Air Traffic Control sound. The guys who give the pilot clearance for takeoff or land. Sometimes also in some specific planes there wont be engine sound if facing straight. i tried to install it and run it with compatibility feature as Windows XP.

Anyone have any idea why or a solution?

Thanks appreciate all the help.