Live music in space has a ritualistic ability to bring listeners into present space-time, to pull them from their future and ongoing life forces. This is used across the world in ancient ceremonies such as by the Aboriginals in Australia, more recently in the Grounation services of the Rastafari and has been abstracted into amazing modern music such as John Hassell's and the 'fourth world music' defined by Eno.
Our perception of the present is however as much informed by our past experience as the present phenomenon. We build up a catalog of reflexes and stimuli memory, as well as emotional associations. This system is complex and rapid, however the participation of interpretation within perception creates space for mistakes and strange phenomena. This is where the area of sensory illusion acts.
The first example of sensory illusion I would like to share is the Shepard-Risset Glissando. I heard about this recently, it's an auditory illusion which is perceived to continuously ascend or descend in pitch. The effect is created by a superposition of sine waves separated by octaves. When played with the bass pitch of the tone continuously gliding upward or downward and being replaced by another like a chain, the pitch seems to continually ascend or descend, yet which ultimately gets no higher or lower.
It's the auditory equivalent to the infamous Penrose Stairs. The filed of optical illusions is of huge popularity and it is within the fringes of perception that considerable attention is payed by scientists and artists.
An extension of the Shepard Tone is the proposed Tritone Paradox:
a sequentially played pair of Shepard tones are separated by an interval of a tritone (half octave). By some it is heard as ascending and by others as descending. Much like The Dress!
Illusions aren't limited to sight and sound. A recent paper by Richard J. Stevenson is getting traction in unveiling the world of olfactory illusions. This blog article gives some nice examples.
I have been excited to learn about instances of illusion within our perception and I've been very impressed by work in the field by Shepard. I like how he bridged the visual with sound and unified all the senses under our mechanisms of perception. We've often worked with the beating effect, which is an interesting auditory effect, but what excited me about some of these other examples of illusion is the possibility to make extremely subjective sounds and effects that break from typical logics. This is brilliant new lens to consider our sound experiments with.
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