The auditory illusion is created with an accelerating and decelerating palindrome phrase on the left channel. In the second part, a phrase of same pitches synthesized by a sine oscillator instead of a step response are followed by their two octave below counterparts. The lower octave pitches are perceived as a group, especially the tempo is increased. Even thought the two phrases consist of same pitch values, they are not aligned to create a mist racking illusion. Moreover, in the second phrase, both stereo channels are used while it is only left channel for the first phrase.
The palindrome is inspired from John Adams’s China Gates. The overall palindrome structure of China Gates is minimized to a single phrase and the accompaniment part is bounced back and forth between two stereo channels.
You can reach the code from: auditoryIllusion.ck
And the sound file: Palindrome from China Gates