That does sound remarkably like a soundcard driver issue to me. I've only experienced this (ie. that buzzing noise, probably actually a soundcard freeze) myself when playing games and only very intermittently (certainly not enough to be annoying or warrant looking into it any further).
I do recommend trying DPC Latency Checker
(a free utility) to see if there is any correlation between the buzzing sound and any recorded latency drop-outs/spikes.
In the first instance, I'd probably make sure that my motherboard BIOS/chipset drivers and soundcard drivers were up to date. Assuming the soundcard is an on-board motherboard soundcard, I'd recommend trying the motherboard manufacture/OEM soundcard driver first (although they are often fairly old) before trying the actual soundcard chip manufactures driver (often more up to date).