Background or ambient noise is the constant hum of the world around you. You may not notice it, because you hear it all the time. It’s your AC, your refrigerator, the aquarium in your office, the hum of lights, or computer fans. In other words, it’s a steady stream of noise. To get an ideal recording environment, you need to get rid of those sounds. However, you don’t have to shut off your AC or refrigerator to get your recording up to professional levels.
Background noise is not random sounds, like barking dogs, trains, footsteps on the floor above you, a doorbell, or the clicking of keyboard keys. These sounds must be removed manually (and can take significant time to extract).