Karyn
...You select a small area with just noise and sample it, then the noise reduction effectively removes that sound from the rest of the clip. You can vary the strength so it's not an all or nothing deal and it works very well.
If you have background noise like air conditioning hum or computer fan noise it will remove that as well.
Thanks for the tip. I'd never used that feature of Audacity before. I tried it today and successfully eliminated a noisy extractor fan from some vocal clips.