Mapping transparency through metaphor: towards more expressive musical instruments

We define a two-axis transparency framework that can be used as a predictor of the expressivity of a musical device. One axis is the player's transparency scale, while the other is the audience's transparency scale. Through consideration of both traditional instruments and new technology-driven interfaces, we explore the role that metaphor plays in developing expressive devices. Metaphor depends on a literature, which forms the basis for making transparent device mappings. We examine four examples of systems that use metaphor: Iamascope, Sound Sculpting, MetaMuse and Glove-TalkII; and discuss implications on transparency and expressivity. We believe this theory provides a framework for design and evaluation of new human–machine and human–human interactions, including musical instruments.