Isoluminance

That sense of unreality was all the more wonderful because the next day I heard sounds as unaccountable as were those lights, and without any emotion of unreality, and I remember them with perfect distinctness and confidence. (Yeats, 2004, p. 139).

There are sounds that present a quality of otherness and have an illusory, almost paranormal quality. They can have an atmosphere of liveliness, unreliability, presence, or mystery. I am interested in sounds that have no discernible source and/or whose presence alludes to an impossible sense of place. The listener can hear it but cannot locate it— as though it were a spirit from another realm. This sonic situation can lead to interesting perceptual results, much like mystical negation.

In the visual realm, this is a situation known as isoluminance and is common in mystical art. Isoluminance can be identified in many religious art traditions, where the divine body is represented as glowing or shimmering. Examples of this can be seen in medieval paintings of holy people, in Hindu and Buddhist art, and in the Yolngu art practice. The divine is represented by light with a shimmer or a glow to represent the spirit. Though isoluminance is a term used specifically to refer to light, there are analogous experiences in sound. I argue though that the ephemerality and time-variable nature of isoluminant phenomena brings this particular visual experience closer to sound and the mystical-ephemeral than to the normal visual sphere. The conflation of location and identification can lead to interesting and somewhat supernatural impressions of objects in space, because the eye can easily identify the presence of an object but cannot easily determine where the object is. Sometimes, when the object is not located in the visual field, the object is interpreted to be from another, possibly spiritual, realm.

In sound, I consider sonic isoluminance to be aberrations in the spatial/locational information gathered from a sound. This would be identifiable as a sonic object but impossible to locate in space, or would seem to have spatial qualities separate from a known listening space. Within this context, isoluminant objects exist almost outside of the realm of space, time, and form. Their conflation of the “where” within the space of the “what” can conjure new, often mystical, sonic experiences and I propose to write a chapter on the meaning of these sounds in a mystical and musical sense.