Additive Synthesis
Digital sound synthesis and audio processing came into being in the late 1950s, as an outgrowth of concurrent work in speech synthesis. Many of the early techniques, such as additive synthesis, based on the use of sums of sine tones or oscillators, FM synthesis, which employs chains of such oscillators as modulators, and wavetable synthesis, making use of stored tables of data read through at variable rates, have become cornerstones of modern synthesis [1].
Sounds produced in this way dominate today’s soundscape—they are familiar to anyone who possesses a personal computer or mobile phone. At the same time, they are undeniably heuristic approaches to synthesis, motivated by perceptual and efficiency concerns—there is no strong underlying physical interpretation for such algorithms.
The benefits of such approaches to synthesis are obvious: conceptual simplicity, and efficiency—and such benefits underlie the continued preeminence of such methods in today’s synthesis software packages. Though powerful, these methods possess two major weaknesses:
● sound quality: output is invariably synthetic, and lacking the warmth, variability, and interesting unpredictability of acoustically-produced sound.
● user control: the necessity of specifying a set of input data which may very large, and/or of obscure perceptual significance.
Wavetable Synthesis
Both these difficulties are at odds with the fundamental goals of many artists and musicians—to have, at one’s fingertips, a flexible sound generation system which is simple to use, intuitive, and which generates sound which is rooted in one’s experiences in the acoustic world. One response to the first difficulty has been the incorporation of recorded audio material, or sampling [2]. Sampling, while very successful at emulating certain instruments (such as the piano), introduces a whole new set of problems: There is an explosion of the memory requirement necessary to capture the full expressible range of an instrument, as well as the difficulty in escaping from the character of these recorded fragments—the ear tires quickly of repetition. The second difficulty is much harder to address (and subjective!): the user may be faced with setting hundreds or thousands of parameters, of obscure perceptual significance. When faced with such difficulties, the musician or sound designer may be forced to retreat to “preset” configurations—and as a result, greatly limiting the potential of these methods.
The point of this project is to explore other techniques—techniques which neatly address the two issues above, while introducing new problems, not least of which is computational complexity!
