ShepardTC

Create a Shepard tone complex for demonstration of pitch circularity

A Shepard tone is a tone complex containing only octave-spaced components and a bell-shaped fixed spectral envelope. It is well defined in pitch class, but ambiguous in pitch height. Sequences of Shepard tones with rising pitch class can elicit an infinitely rising pitch scale. Differently from Shepard's original work, here the spectral
envelope is a cos^2 shape of the amplitudes, not sound levels.
Ref: Shepard R.N., J. Acoust. Soc. Am. (1964) 36(12), 2346-2353
Deutsch, D, Acoustics Today (2010) July, 8 - 15
See also Deutsch D., THe Psychology of Music, 3rd Ed., London, Academic Press, 2013, Ch. 7.V