I am occasionally getting a buzzing sound in my video when I play back video. I also hear the problem in my Blender sequencer. Blender is the Open Source 3D graphics program that also includes a video sequencer.
This YouTube video exhibits the problem. Skip to 1:26 to hear it right away. My problem does not get as severe as seen on this video.
I have a dual screen setup on a laptop computer. That is, I have two external monitors hooked up to a laptop, I do not use the laptop screen for working on the computer. The laptop is an AO756 Acer One.