All too often the audio we record captures sounds that we would prefer to leave out. Examples of this might be an overhead fan when indoors or crickets when outdoors. Technology allows us to do radical things to the audio track of video.
In many cases we can actually remove or at least reduce an isolated sound such that it becomes insignificant. One of the great examples of this is audio feedback. There have been times when ear-shattering feedback rang through a public address system as we captured our video. In all cases where we have encountered this we were able to radically reduce the feedback to the point where the viewer wonders why the people in the video are shaken.
The process of removing isolated sounds relies on a principle developed by the eighteenth century French mathemetician named Jean Baptiste Joseph Fourier.
Consider the case of removing the sound of an overhead ventilation system from the audio track of a video. In order for the removal of the offending sound to be effective we must be able to locate somewhere in the video about one second of silence in which the sound is present. An analysis is performed on that silence and the result applied to the entire audio track. In most cases the fan noise can be reduced quite effectively.
