TABLE OF CONTENTS In the early days of sound recording, signal storage was a major problem. The final recording was laid down directly, without benefit of stop-and-go recording of portions that could be patched together later. This had the advantage of minimizing the number of recording generations, but the format was a stringent one with little latitude for artistic enhancement.
With the introduction of high-quality signal storage (magnetic tape or digital memory) many creative decisions, normally reserved for the recording session, were moved to the mix-down session. This opens up the opportunity of making quality enhancements in the mix-down session, long after the recording session is finished and forgotten. These quality enhancements are often made with filters of one kind or another. Is there a short traffic rumble on take 6 of the recording? A high-pass filter might cure it. Did that narrator's dentures contribute an occasional high-frequency hiss? Run it through the "de-esser." How about that congenital 3 dB sag in the response at 4 kHz? Easy, add a 3 dB peak of appropriate width with the parametric equalizer, and so on.
The introduction of integrated circuits in the 1960s made signal processing equipment lighter, more compact, and less expensive. The coming of the digital revolution made it possible to routinely accomplish sophisticated signal processing tasks, heretofore impractical or impossible. This chapter is a very brief overview of both analog and digital sound processing principles and practice, especially the principles.
The man on the stage is doing the old...
