A Shepard tone, is a sound consisting of a superposition of sine waves separated by octaves. When played with the base pitch of the tone moving upwards or downwards, it is referred to as the Shepard scale. This creates the auditory illusion of a tone that continually ascends or descends in pitch, yet which ultimately seems to get no higher or lower.
(Like the end of Muse's "Ruled by Secrecy")

"Barber-Pole" Flanging, Known as Infinite Flanging is a sonic illusion is similar to the Shepard tone effect. The sweep of the flanged sound seems to move in only one direction ("up" or "down") infinitely, instead of sweeping back-and-forth. While Shepard tones are created by generating a cascade of tones, fading in and out while sweeping the pitch either up or down, barber-pole flanging uses a cascade of multiple delay lines, fading each one in to the mix and fading it out as it sweeps to the delay time limit.

Anyone know any Pedals That do this?