Ad Hoc Recording Studio

Background
For serious high quality recording, here are some suggestions for controlling background noise by recording in a separate room - a cheap DIY recording studio setup. The principle is simple:
 * Get the computer out of the (recording) room.
 * Retain as much as feasible of control (keyboard, monitor, mouse) in the recording room.
 * Get a grip on room acoustics.

Computer location
A completely silent computer is pretty rare what with fans and hard disks clicking. Even some monitors can even have a bit of low hum, although LCD monitors are far less likely to produce this effect. For a truly quiet recording environment, there are only two solutions:
 * 1) acquire a "silent" computer,
 * 2) relocate your noisy computer in one room and record in a quieter room with the door closed.

Silent computers generally use the latest generation of laptop hard disks, which are extremely quiet, and a fanless power supply. You can find reviews and information about "quiet", "low noise" and/or "silent" computers at silentpcreview.com.

If the computer is in another room, that leaves the problem of starting/stopping or adjusting the recording. Some audio programs have a count-in interval which can be used to give yourself a few seconds to walk to the next room before recording starts. This helps but can result in lots of dead air and the hassle walking back and forth when recording numerous takes trying to get that perfect one.

A good solution is to get a long keyboard extension cable and set a keyboard next to the mic - finally a use for that old keyboard that came with your previous computer! Wireless keyboards also work nicely if not too far away. Search Google for a suitable model. You can then sit at the mic and use the keyboard shortcuts like R for record, S for stop, CTRL + Z to undo the recording, R again to start a new track if you screw up a take, Spacebar for playback, and so on. A disadvantage is that you have no visual confirmation that recording is taking place, but it is not that hard to train yourself to hit the keys in the right order. If you always hit S before hitting R it is pretty foolproof. You can see Audacity's Keyboard Shortcuts in the latest Manual.

Another useful thing is a pair of headphones in your recording room, also of course requiring a long extension. Using the keyboard shortcuts you can basically sit there indefinitely recording, listening to takes, and recording more without so much as needing to look at your computer.

An actual monitor in the recording room can also be done (yet another use for yesteryear's spare computer equipment.) Though monitor extension cords may not be available, it is possible to put a hole in the intervening wall and pass a relatively short monitor cord through back to the noisy computer. With a monitor you will probably want a mouse as well, using either the hole in the wall pass-through trick or (yes) yet another long extension cord.

In a pinch, if the room has a window or a glass door, you can set your recording laptop on the other side of the glass for full visual access. Just don't leave it out in the rain or drop it off the ledge.

Room acoustics
Although many people think that a recording studio should be acoustically dead, some reverberation can be desirable to get a natural-sounding recording. Common challenges in recording studios are flutter echo (from flat, parallel room surfaces), Low frequency room modes (more of a problem in smaller rooms), and poor frequency response. You may try to dampen any echo by hanging up blankets or bed sheets.

Also see chapter 21 of Master Handbook of Acoustics By F. Alton Everest, Ken C. Pohlmann. An online preview is available here.