For Ann (rising)

The piece is based upon the Shepard scale concept, named after Tenney's colleague at Bell Labs psychologist Roger N. Shepard, though the technique which the piece uses is more properly described as a continuous Risset scale or Shepard-Risset glissando. (Polansky, 2003)

Each rising sine-wave-like glissando, between twelve and fifteen rising at any time, fades in and out, all entering a minor sixth below their predecessors, rising from the infrasonic to ultrasonic range, from below to above the ability to perceive pitch. (Polansky, 2003)

While the original experiments were intended to illustrate a property of human perception, Tenney's piece problematizes it:

One simultaneously perceives the lines as forming one continuously rising line, yet one is constantly aware of shifts in perception from line to line or lines. According to reviewer Jeremy Grimshaw, "there emerges at the upper frequency threshold a crystalline conglomeration of extremely high pitches, which glimmer as an indistinguishable mass even as glissandi continually enter the top range and fade" According to his friend Philip Corner For Ann (rising), "must be optimistic! (Imagine the depressing effectiveness of it -- he could never be so cruel -- downward)..." (ACG)

Tenney has suggested the piece be "regenerated" with the distance between successive voices, the minor sixth (justly, 1.6), being tuned to phi (1.618), the limit of the ratios of successive terms in the Fibonacci sequence. This is desirable because then all first-order difference tones between adjacent voices would be present in lower voices.
(Polansky, 2003)

Sources