TABLE OF CONTENTS The term comb filter has been widely used in the popular audio press as an explanation of delayed reflection effects. Comb filtering is a steady-state phenomenon. It has limited application to music and speech, which are highly transient phenomena. With transient sounds, the audibility of a delayed replica is more the result of successive sound events. A case might be made for proper application of combing to brief snatches of speech and music that approach steady state, but already there is an etymological impasse. The study of the audible effects of delayed reflections is better handled with the generalized threshold approach of Chap. 16.
A filter changes the shape of the frequency response or transfer function of a system. An electronic circuit used to shape the frequency response of a system to achieve a certain desired end could be a filter. A filter could also be a system of pipe and cavities used to change an acoustical system, such as is used in some microphones to adjust the pattern.
In the early days of multitrack recording, experimenters were constantly developing new, different, and distinctive sounds. Phasing and flanging were popular words among these experimenters.1 At first multiple-head tape recorders were used to provide delayed replicas of sounds that were then mixed with the original sound to produce some unusual and eerie effects. Currently special electronic circuits are used to generate these delays. Whatever the means, these audible colorations of sound...
