crackling speakers…on new PC

My friend has a brand new PC , they bought From a TV ad, The speakers crackle and sound staticky , especially when you move the mouse. , the static sounds like it is part of the mouse.What causes this? This static is so annoying that after about 20 minutes on the PC you can’t wait to just shut it off and not bother with it.Also these speakers are the second pair the’ve tried . the speakers that came with the PC was even louder than these ones are.
Thanks for any help with this problem.
its worth 500 points to me for the answer that solves the problem.