To quickly reduce noise from a waveform, select at least one half second of the file (preferably one with only the noise to be removed and no foreground audio) in Edit View. Then, choose Effects > Noise Reduction > Noise Reduction. Click on Get Noise Profile From Selection to sample the noise. (If this option is unavailable, lower the FFT size.) Next, click on Close, select the entire file (or just the portion you want apply noise reduction to), go back to Effects > Noise Reduction > Noise Reduction, and click on OK to perform the noise reduction.