Abstract
This article describes methods of sound synthesis based on auditory distortion products, often called combination tones. In 1856, Helmholtz was the first to identify sum and difference tones as products of auditory distortion. Today this phenomenon is well studied in the context of otoacoustic emissions, and the “distortion” is understood as a product of what is termed the cochlear amplifier. These tones have had a rich history in the music of improvisers and drone artists. Until now, the use of distortion tones in technological music has largely been rudimentary and dependent on very high amplitudes in order for the distortion products to be heard by audiences. Discussed here are synthesis methods to render these tones more easily audible and lend them the dynamic properties of traditional acoustic sound, thus making auditory distortion a practical domain for sound synthesis. An adaptation of single-sideband synthesis is particularly effective for capturing the dynamic properties of audio inputs in real time. Also presented is an analytic solution for matching up to four harmonics of a target spectrum. Most interestingly, the spatial imagery produced by these techniques is very distinctive, and over loudspeakers the normal assumptions of spatial hearing do not apply. Audio examples are provided that illustrate the discussion.
Supplementary data
Direct Additive Synthesis: Example 2a
Direct Additive Synthesis: Example 2b
Direct Additive Synthesis: Example 2c
Direct Additive Synthesis: Example 2d
Direct Additive Synthesis: Example 2e
Direct Additive Synthesis: Example 2f
Dynamic Sinusoidal Synthesis: Example 3a
Dynamic Sinusoidal Synthesis: Example 3b
Dynamic Sinusoidal Synthesis: Example 3c
Single-Sideband Modulation: Example 4a
Single-Sideband Modulation: Example 4b
Single-Sideband Modulation: Example 4c
Single-Sideband Modulation: Example 4d
Spatiality: Example 6a
Spatiality: Example 6b