Inspired by the Shepard Tone first described by Roger Shepard in 1964, Spira uses a bank of resonant bandpass filters to create the illusion of a never-ending, layered, overlapping glissando. The glissando effect is produced using the resonance of the filters, and can be applied to any instrument.
Spira sounds as if it is continually and infinitely sweeping either up or down, creating musical tension and energy. Its texture and sweeping motion are perfect for psychedelic, drone, and ambient styles, and anywhere else you want to add movement to your sound.
