I have just upgraded Audacity on my Mac after having to get a new hard drive. I am also using a brand new logitech headset. I am hearing a disruptive hummm in the background of my voice track. It is not present on my background music track. How in the world can I get rid of this hum? I am creating a hypnotic recording and have not experienced this before that I recall?
I would so appreciate a timely answer because I must deliver this recording today, with or without the hum 
Thank you,
Julia
Moved to the correct Mac OS X board.
If it’s a USB headset, plug into a spare USB port on the computer or into a wall powered hub.
Mild hum could be removed with Effect > Noise Removal….
Gale
My USB headset does that, too. It’s very sensitive to other electronics on my desk. Mine can pick up hum from my large monitor. Try moving around while you listen to yourself.
Koz
Another one. Try to wrap the headset cable around your hand and then touch something metal like a desk lamp or the front of the computer. I have one microphone which works perfectly well when I do this.
Koz