Endlessly accelerating beat rhythms are Shepard tones shifted down in frequency.
Evidence
As Risset also realized, the general ideas behind Shepard tones can be applied to rhythm by using several percussionists, bringing in the slowest beating softly, everyone speeding the beat up from moment to moment, and fading percussionists out as their beat gets very rapid (figure 23.20). A percussionist who has been thus eliminated returns to soft slow beating, and so on. In section 23.22, we suggest that the concept of pitch be extended well below the nominal 20 Hz lower frequency limit of human hearing. In this light, the Risset beats and Shepard tone phenomena are the same—both are playing the same game with pitch. — Eric J. Heller, Why You Hear What You Hear- An…, 2125
Categorization
Category: Causal Relationships
- XREF: Strongly connects to the reader’s existing interest in low-frequency and infrathreshold phenomena, and to the chapter 22 themes around sub-20Hz sound.
- ADDENDUM: Could feed the reader’s broader sonic-illusions work by unifying Shepard tones with rhythmic illusions via pitch extended into infrasonic territory.
Related
- Tempo can be made to loop infinitely via layered sped-up copies with faded amplitudes (similarity 0.84)
- Shepard tones create endlessly rising pitch through shifting autocorrelation peaks (similarity 0.82)
- A sound can rise in pitch forever without ever rising in frequency (similarity 0.82)
- Shepard tones are not perceptually identical across the octave. (similarity 0.81)
- Shepard tones use only power-of-two partials plus amplitude shaping to create the illusion. (similarity 0.80)
- A Shepard tone creates an endlessly ascending pitch while staying within one octave (similarity 0.80)
- A rising pitch can perceptually loop back to its start. (similarity 0.79)
Broader Connections
- Tempo can be made to audibly accelerate forever by layering tempo octaves
#corroborates(0.95) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1658 - A Shepard tone creates an endlessly ascending pitch while staying within one octave
#expands(0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1641 - Shepard tones are not perceptually identical across the octave.
#complicates(0.75) — Eric J. Heller, Why You Hear What You Hear- An…, 2120 - Low-frequency tones become relatively louder as level increases.
#expands(0.75) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1172