Synthesis and Control of Hundreds of Sinusoidal Partials on a Desktop Computer without Custom Hardware

The idea of synthesizing sounds by summing sinusoidal oscillations [Helmholtz 1863] has intrigued generations of musical instrument builders. Thaddeus Cahill's electromechanical implementations [Nicholl 93] illustrate graphically the basic challenge faced by these engineers--the creation of a large number of oscillators with accurate frequency control. (...) One hundred years after Cahill's work, despite rapid gains in computational accuracy and performance, the state of the art in affordable single chip real-time solutions to the problem of additive synthesis offers only 32 oscillators. Since hundreds of sinusoids are required for a single low pitched note of the piano, for example, current single chip solutions fall short by a factor of at least 20. This paper describes a new technique for additive synthesis, FFT-1, that offers a performance improvement of this order. This technique also provides an efficient method for adding colored noise to sinusoidal partials, which is needed to successfully synthesize speech and the Japanese Shakuhachi flute, for example. Before describing the details of the FFT-1 method, additive synthesis will be compared to the popular synthesis methods: frequency modulation [Chowning 73] and digital sampling.