by stephen barrass
presented at the Australian Computer Music Conference at the Australian National University in Canberra, 1994
Abstract
The hue, saturation, lightness (HSL) colour model is an intuitive interface for interaction with the... more
Abstract
The hue, saturation, lightness (HSL) colour model is an intuitive interface for interaction with the millions of colours which are available in high quality colour processes. This interface makes it possible to specify colours in a natural manner, to manipulate the subjective dimensions of colour independently, to use geometric paths to specify ordered sequences of colours, and to use a system which does not depend on a particular colour output device.
This paper proposes a naturally ordered geometric model of sound, derived from considerations of the form and properties of the HSL colour model. The recognition that both hue and timbre are categorical perceptions is the link which allows the creation of a cycle of timbres which mimics the hue circle. There is no consistent ordering of timbre but it is hypothesised that a subset of timbres may be arranged in a circle by a pair of underlying perceptual axes. The Timbre Circle, in which the most similar timbres are adjacent, and the most dissimilar lie diagonally opposite, is investigated by implementing several such sequences based on dimensions of timbre identified in the psychoacoustic research studies of von Bismarck, Slawson and Grey. A complex timbre attribute consisting of a spectral and temporal component is proposed as the basis for an extension of the Timbre Circle with an independent naturally ordered radial component to form the Timbre Wheel. Brightness is identified in many timbre spaces as the most important aspect, and has been shown to have a perceptual metric. An example of a Timbre Wheel in which brightness is the radial component is implemented and various sequences such as a diagonal and a spiral are used to confirm perceptible ordering and smooth transition through the centre which supports the polar geometry. The sound model is completed by choosing pitch over loudness as a vertical axis, analogous with the lightness axis in the colour model. The result is called the Timbre, Brightness, Pitch (TBP) sound model. The generality of the model is demonstrated by fitting Gaver’s “everyday” synthesis algorithm within the framework.
The TBP sound model is illustrated with a SoundChooser graphical user interface similar to the colour chooser found in many colour applications.
Keywords Colour, Sound, Perception, Synaesthesia, User Interface
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