The Shepard Scale
One of the more widely used auditory illusions is Shepard's demostration of pitch circularity.
The demostration uses a cyclic set of complex tones, each composed of 10 partials separated by octave intervals.
The result is an "ever-ascending" scale.
- Click on the names in order round the circle, clockwise.
Do you hear the pitch as continuously rising? Or does it sometimes fall? - Click on the names in order round the circle, anti-clockwise.
Do you hear the pitch as continuously falling? - Try some other intervals, eg. click C and then E.
- Try them backwards eg. E then C.
Click here to listen to the ascending Shepard scale
Click here to listen to the descending Shepard scale
The continuous scale of J-C Risset
Several variations of the Shepard scale have been described. J-C Risset created a continuous version.
Analytic vs. Synthetic Pitch
A pair of complex tones is played four times against a background of noise.
Do you hear the pitch go up or down?