Bobi, it's obvious that the hum I'm getting is noise from the hard drive.   What's not clear to me is why this wasn't an issue when the laptop was newer - with my original built-in mic/cam before it started acting up (possibly as a result of a cat knocking the laptop off a chair onto the floor);    The hard drive makes noise sometimes and doesn't at other times.

There are really two questions about that, but they're not really the issue in this thread. Yes, I'd like to know how to use the built-in mic without getting the machine noise (e.g., if I reduce the volume on the sound input, would that help?).   And if I use an external mic, what's the best one (or type) to use in an acoustic, unamplified setting where there may be multiple performers and I may not be able to have the mic closer to the performers than about 6 to 8 feet?

Mick (MCP), I think I did unselect the short noise clip first, but it's not clear how to do that. Do I copy the clip first?    If I select the brief noise clip and then unselect it, how does Audacity know that's the clip I want used?    I can't do any selecting or unselecting while I'm in the Effects menu (e.g., on "Noise Removal").    I tried this and that sequence but it never seemed to do anything, so obviously I'm not doing it right. Thanks for those setting suggestions. I'll try that.


BTW, it seems GarageBand can do some of this, but I'm still experimenting to figure out how. They have an "Au Filter" setting that lets you reduce the volume on parts of the auditory spectrum and if I reduce the very high treble it does cut out a lot of the hum, but it also can make the voices and instruments sound mushy if I remove most of the hum.   They also have a couple of preset filters that you can play around with to see which ones may help with this.