I have been doing a lot of editing in Audacity recently, and mostly through trial and error, I have developed a workflow that works well for me. Today I am going to discuss how I remove noise from an audio clip. First, I open the clip in Audacity and listen to it. I have experimented with listening to cclips at different sound levels and I have found that setting the volume on my headset about halfway between the softest and the loudest levels works best. I look at the wave form and select a few seconds of noise. The screen shot at the top shows what noise looks like. I open the Effect menu on the menu bar and select Noise Removal. On this screen I click the Get Noise Profile button to let the noise removal tool analyze the sounds I want to remove from the clip. I return to the wave form and select all of it. I open the Noise Removal tool again and usually set it to remove 6 DB of noise. I never change the other two options, Frequency Smoothing and Attack/Decay time. I click the OK button to close this dialog box. I return to the clip and listen to it again. It works well for me if I remove noise in increments of 6 DB. If the clip was recorded at a very loud volume I remove 12 DB of noise. If you are too aggressive in removing noise the clip will have a hollow sound sort of like an echo chamber effect.
In future posts I will cover other auditing tasks in Audacity, such as removing clicks and clipping.