buzz??

Pinknoise? a sample from some GM synth continuing, as you say at a second bar etc.

Sideliner PS: guess the sky is the limit when you say 'buzz'.

Seen a few in the past LoL: Audio interference from a lamp on an USB soundbox?
An flyby insect caught in a PC fan, or a case with a loose screw ...

Continuous to me could mean some audio interference; did you change anything inside your Computer?

Speaker- or flaky audio wiring too close to a power line, TL tubes close; a power-supply can also break down causing trouble, internal ones or even if you use an external audio interface ...