Colour Music

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

Il saggio analizza tre casi studio di collaborazioni tra artisti e aziende ritenuti particolarmente emblematici poiché nella prima metà del Novecento hanno portato all’invenzione di dispositivi sonori e/o luminosi destinati ad un’esecuzione dal vivo e all’istituzione di dipartimenti di ricerca congiunta tra ingegneri e artisti: l’incontro nel 1927 tra il dadaista Raoul Hausmann e l’ingegnere Daniel Broido dell’azienda elettrica AEG di Berlino che conduce al brevetto dell’Optofono, un dispositivo di conversione di luce in suono e viceversa; la collaborazione tra il direttore d’orchestra Modest Altschuler e l’ingegnere Preston S. Millar dell’Electrical Testing Laboratories che porta alla realizzazione del Chromola, un proiettore/tastiera di fasci luminosi; la mostra Nine Evenings: Theatre and Engineering, curata nel 1966 dall’artista Robert Rauschenberg e l’ingegnere della compagnia Bell Telephone Laboratories Billy Klüver, a partire dalla quale nasce il dipartimento E.A.T. (Experiments in Art and Technology), un centro di ricerca e sviluppo ad opera di artisti e ingegneri della Bell Telephone Laboratories. L’obiettivo è quello di portare in luce il ruolo che gli artisti hanno avuto nel corso del Novecento come attori di anticipazione, sperimentazione e promozione di innovazione e sviluppo non solo di artefatti tecnico-culturali, ma anche di pratiche discorsive e metodologie di creazione e condivisione di sapere.

A forced choice paradigm was employed, similar to that of a recent experiment conducted by Hubbard (1996) using paired greyscale patches and pitch intervals, which provided evidence of a universal mapping of lightness value relative to pitch height. In the current experiment we used colour, instead of greyscale, and tonal intervals within the normal vocal and instrumental midrange. 40 participants chose between colour combinations derived from two models of pitch-colour correspondence in response to intervals and dyads from all 48 major and minor keys in the cycle of 5ths. Analyses revealed a tendency to map adjacent colours onto close intervals and relate spectrally distant colours to larger intervals, particularly amongst those with musical training, but also among participants with training in visual arts. This experiment provides evidence of a perceptual analogy between pitch and colour relationships, as well as some support for the traditional linear model of pitch-colour correspondence.