weird macbook pro external speakers popping/crackling

I use external speakers on my Macbook Pro, and lately whenever the furnace kicks on there's popping/crackling that happens in the speakers. It doesn't do it when I plug my Macbook (plastic) into the speakers.

Could the metal of my MBP be picking up some sort of interference?

i did a PRAM reset and a disk repair on my MBP, and it seems to have lessened it a bit.

Anyone else ever had this happen?

OmahaGTP said:

Probably akin to having lights dim ever so slightly when something like the furnace comes on. Just voltage fluctuations. Have a good quality battery backup/line conditioner? Something that keeps a good consistent voltage.

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I don't, but may be purchasing one. It happens even when my MBP is on battery power though, so it must be the speakers. My apartment has a large amount of static electricity for some reason, so i wondered if that could be the issue.

if it is a fluctuation, will it hurt my computer?