Logitech Z4 speaker's noise

[flip__]

I have Logitech Z4 speakers since some years ago, but since some weeks ago I'm listening a strange noise (like some interference) in the left speaker (I think it comes from the upper "ball"). Sometimes I hear that noise from right speaker, but it's lower.

This noise appears every time the speakers are turned on, even when I'm not playing any music. And this also happens even if I unplug the speakers from the laptop.

I noticed that if I plug my headphones to speakers, the noise disappears, but it appears on left speaker of headphones!... It's very strange.

Anyone knows what can be causing this problem? This is very annoying.

Thank you, and sorry for the bad English.

 

[soundguruman]

It might be a radio transmitter, but we could not tell, until you post a recording of the noise.

 

[flip__]

I've already tried to do that, but I wasn't sucessful with my phone, because the sound is not audible on the recording. I'll try to find another way to record it, and I'll post it.