I use a set of external USB speakers at the office which have no power-source other than my laptop USB port. Sometimes they're silent, and at others it sounds like an electric moth is fluttering around inside the main speaker, or perhaps it's best described as rapidly-fluctuating static. This doesn't happen when my machine is doing any heavy crunching, it just comes and goes.
This has happened with other USB speakers on other laptops too in my experience. Any idea on what causes this, and how I can fix it?
Update
I unplugged the speakers from the audio jack on my laptop but left them plugged into the USB port. I've not heard the flutter for several hours now, so I'm certain it's not a power-issue - at least not a power issue with regards to the USB port...