Abstract Digital Sound Synthesis

The earliest stage, beginning in the late 1950s and continuing until the present day, saw the development of abstract synthesis techniques, based primarily on operations which fit well into a computer programming framework: the basic components are digital oscillators, filters, and stored ``lookup" tables of data, read at varying rates. Though the word ``synthesis" is used here, it is important to note that in the case of tables as mentioned above, it is of course possible to make use of non-synthetic sampled audio recordings. Nonetheless, such methods are often lumped in with synthesis itself, as are so-called analysis-synthesis methods which developed in the 1970s after the appearance of the Fast Fourier transform [60] some years earlier. It would be cavalier (not to mention wrong) to assume that these techniques have been superseded; some are extremely computationally efficient, and form the synthesis backbone of many of the most popular music software packages, such as Max/MSP [248], pd [164], csound [36], SuperCollider [144], etc. Moreover, because of their general accessibility, they have entered the lexicon of the composer of electroacoustic music in a definitive way, and, as a result, have undergone massive experimentation. Not surprisingly, a huge variety of hybrids and refinements have resulted; only a few of these will be detailed here.

The word ``abstract," though it appears seldom in the literature [207,219], is used to describe the techniques mentioned above because, in general, they do not possess an associated underlying physical interpretation. In other words, such sounds are produced according to perceptual and mathematical, rather than physical principles. There are some loose links with physical processes, most notably between additive methods and modal synthesis (see §1.1.1), subtractive synthesis and source-filter models (see §1.1.2), and wavetables and wave propagation in one-dimensional media (see §1.1.3), but in general, it is best to think of these methods as pure constructs in digital signal processing, informed by perceptual, programming and sometimes efficiency considerations. For more discussion of the philosophical distinctions between abstract techniques and physical modeling, see the articles by Smith [207] and Borin et al. [33].