Target managed the upsell. I went in shopping for a cheap desktop microphone and walked out with a $35 headset (the Logitech h390). The noise cancellation features combined with the proximity to my face made its promise of quality sound seem plausible. However, my first recording had a serious hum. I adjusted the settings on the computer so that I could listen to the input in real-time (an option in the Recording Device properties), which confirmed that the hum was either system-wide or microphone-specific. Either way, I could not blame it on the recording software. It varied some based on position, which confirmed for me that it was feedback and not just system noise.
I found two ways that the hum basically went away at my desk:
- Grasp the touch-activated lamp in the office (discovered while looking for a way to ground myself).
- Hold the mic very close (within an inch) to the laptop screen or keyboard (as seen here).
Given that both options were functionally useless discoveries, I was about ready to give up. No amount of unplugging made a difference -- I unplugged everything from the power strip, including the laptop, monitor and printer.
However, I work in an old building with florescent lights and and old electrical system. So, on a whim, I took my laptop and the headset to a different room. Voila! The sound was perfectly clear. It turns out that my desk must be located amidst an unusual amount of electromagnetic radition. That is a little unnerving in terms of what I must be exposed to every day, but at least I can make a screencast that sounds great now!