The "Air Worm": An Interface for Real-time Manipulation of Expressive Music Performance

Expressive performance of traditional Western music is a complex phenomenon which is mastered by few, and yet appreciated by many. In this paper we explore various ways of interacting with expressive performances using methods that are accessible to non-expert music-lovers. A digital theremin is used as an input device, and users can control the two most important expressive parameters, tempo and loudness, during playback of an audio or MIDI file. Several modes of operation are possible: the “Air Worm” builds on previous work in performance visualisation, where the tempo is displayed on the horizontal axis and loudness on the vertical axis in a two-dimensional animation; the “Air Tapper” uses a conducting metaphor where the beat is given by the minimum vertical point in a quasi-periodic trajectory; and the “Mouse-Worm” allows users without a theremin to use a standard input device as controller.