Micah uses Audacity and he gets an intermittent hum on his microphone. Leo says that the mic Micah uses is USB and so a hum can't really find its way into the chain because the power is coming from the laptop, not an analog phantom power source. It could mean that the Digital to Audio converter is going bad, but if there's no analog loop, then there can't be a hum. So it must be software.
Leo recommends Adobe Audition, but he'd have to pay for it. He should at least go in and look into Audacity's settings to see if there's anything amiss. He should check out the mixer. The chatroom says it could be the mic, but Micah says it only happens in Audacity, so it can't be the mic.