James Tenney: For Ann (rising)

(http://www.thatsplenty.com/2006/08/)

Composed by Jim Tenney in 1969 For Ann (rising) is a piece of electronic music that creates the sensation of a continuous ascending sound. It is a deceptive sensation (the way in which Escher created the visual impression of continuous stairs in his Ascending and Descending).

(video by saombra)

Tenney got this by using a superposition of sine waves, each one starting in infrasonic and ending in ultrasonic - each wave takes over the precedent one. The concept is known as the Shepard scale (more precise the Shepard-Risset glissando). It was used also by Ligeti in L'Escalier du Diable.

The following video gives a graphical explanation of the Shepard scale.

(video by 924Dorbe)

(James Tenney)