Getting a strange sound from speakers(ground out?)

[ricker91878]

Lately I've noticed that at certain time, seems like it does it when my a/c compressor kicks on the fans, with my stereo on I get this small hum of bass then it goes away. It does come and go, first noticed it when I would plug my phone into the lighter to charge it would do it every few minutes until unplugged. Doesn't seem to be messing anything up I was just wondering if anyone else has experienced this and if there is a rememdy for it. I'm good with electrical and almost think something is grounding out maybe, any advice though would def. help, thanks guys!