Functional Colour

Functional colour is a design technique for auditory interfaces where visual colour distinctions are replaced with alternative identifiers — typically numbers or mnemonic labels — that convey the same categorical or grouping information through non-visual channels. For example, in an auditory version of a game that uses seven colours to distinguish different pieces, functional colours might use the digits 1 through 7 instead. The concept addresses a fundamental challenge in non-visual interface design: rather than attempting to literally describe visual colours (which provides no useful information to someone who cannot see the display), functional colours encode the purpose the colour serves — distinguishing categories — in a form that is concise and meaningful in an auditory context. This approach exemplifies the broader principle that accessible design should translate function rather than form.