I thought I was going crazy earlier this morning - kept hearing that sound and was checking phones and other devices without success. Since seeing this and realizing I'm not the only one, I now know I'm not having auditory hallucinations. It seems to happen only when army.ca is open and happened on both android and MS platforms. I also opened Edge (using it for this) and the buzzing came up before I logged in or went into any forums. Has been silent for a while now.