How do you remove that background noise?

The “Ask a Producer” series features a conversation with an expert video producer to get answers to your questions regarding video production for businesses. “How do you remove the background noise?” usually comes up when there was a breakdown in the pre-production process. In other words, more attention should have been paid to background noises during the location scout or at the very least, right before you began recording on the set. For more information on the various stages of production for corporate video check out The Four Stages of Production.
Chris Karel: How do you remove that annoying sound in the background?
Neil McCormick: No! The answer is “No.” We cannot remove that background noise.
CK: Sometimes you may end up recording video in a place that you didn’t get to scout, or maybe you have to change locations at the last second, and the room has a noise that is unbearable. This is a bad situation and should be avoided by stressing the importance of the location scout. Best laid plans aside, sometimes you end up with an annoying background noise and we often get asked, “Can you just knock that out?” And what’s the answer?
NM: Um, NO! The bottom line is there’s only so much you can do. An editor can apply a filter to remove certain sounds, but removing a noise will also remove some of the sound you want to keep. The best thing to do is scout and make sure your audio signal will be clean. HVAC in the form of air conditioning or heating ducts is the number one cause of background noise. Appliances like refrigerators can also be a nuisance on a professional microphone. Try to turn off the source of the noise if possible.
CK: The vibration of fluorescent lights can also create noise. I suggest turning them off to avoid the sound.
NM That’s true. They can have a whine to them.
CK: So the best way to remove background noise from the footage you shoot is to never put it in there in the first place.
NM: Absolutely. Pay attention to the silence. Good audio separates amateur from professional video.