To remove background noise with audacity, start your recording, DO NOT make anyyyy noises or touch or click anything for about 5-8 seconds. record your voice or something for a bit, maybe 20 seconds of voice. NEXT On the top menu part, click EFFECT. Then look for NOISE REMOVAL. Click this. Make your settings like this. Noise reduction 24. Sensitivity 0.00, Frequency smoothing 150,attack decay time 0.15. Make sure the bottom part it set to remove, not isolate.. Setup should be done. Now get out of that for a second. Time for the actual noise removal. Highlight (click on the actual soundbar where you see your sound waves) highlight the 5 or so seconds of silence. While that is highlighted, go back to effect, noise removal, then click GET NOISE PROFILE. It now sees what you are trying to get rid of. Click CONTROL+A at the same time and it will highlight the whole track. Simply do effect, noise removal, and click the OK button this time. And you're done.