Speaker buzzing

For some reason, the speakers of my computer buzzes, and the buzzing noise is sometimes different depending on what I'm doing. It makes the most noise when read/write on the HDD. The noises are not that loud, it just is starting to annoy me. It most likely isn't a sound card/motherboard problem because when I use my headphones, it doesn't buzz. This happened on my old computer when I used these speakers. These are USB powered speakers that is the old Wal-Mart brand I bought in about 2008.
(The noises was always there and I am just now annoyed by it)

I have tried my headphones and it doesn't have a buzz. It doesn't matter if I use the front or back port. One interesting thing, for some reason, if I touch the metal part of the audio plug, I used to be able to hear a radio broadcast. But that doesn't happen here in Korea.

Is it safe to use though? I read before that it may be the ground of the audio connection getting interfered by another cable. It didn't say that it is necessarily harmful. I'm just not sure about if my problem is that.

Well, it seems that the power source doesn't matter. Maybe the audio cable is badly insulated/shielded? If it is safe to run it like this, I am ok about keeping it like this.

Well, I guess I'll get new speakers when I have the chance to.

Just my two cents worth mate it could be just the voice coils within the speaker have taken a hiding (electronically) - the speakers dropped (physical misalignment of the coils) or just old age


PS Should have mentioned though not with piezoelectric types