John M. Chowning
Professor of Music, Emeritus
Stanford University
Palo Alto, California, United States
AES 151st Convention
October 20-23, 2021
John M. Chowning presented the second part of his Richard C. Heyser Memorial Lecture during the 151st Convention:
Part 2: Implementing FM Sound Synthesis
While studying music in Paris in 1959, I heard electronic music composed for four loudspeakers surrounding the audience — what today we refer to as "quad." Struck by the feeling of space in this quad format, I imagined composing sounds that could move freely in more complicated paths, changing in azimuth and distance as an addition to the traditional parameters of music, pitch, loudness, and timbre.As a graduate student at Stanford my idea of sound in space remained but a dream. Then in November 1963 Max Mathews writes, "There are no theoretical limitations to the performance of the computer as a source of musical sounds". Max saw the future transformation toward digital technology: any sound wave can be approximated based on the sampling theory. And so, at 29, with years of music studies behind me, but never having even seen a computer and with no background in technology, but with good ears and a musical goal, I began!
While looking for synthesized sounds having internal dynamism that would be perceptually distinguishable from their reverberant field, I experimented with extreme vibrato and with the computer there was no practical limit to either the depth or the rate. I produced a number of different timbres, having both harmonic and inharmonic spectra. That is the story that I present at the 2021 New York lecture, as FM synthesis. I continued building programs to allow arbitrary sound trajectories in a quad space. I realized that I could increase the effectiveness of the distance cue, by localizing the reverberation with increasing distance.
Finally, why do Lissajous figures have anything to do with moving sound sources. At the end of this presentation I will show convincing sound synchronous animations that demonstrate their improbable association with spatialization.
