Music communication as studied by means of performance

This article presents an overview of a long-term research work with a rule system for the automatic performance of music. The performance rules produce deviations from the durations, sound levels, and pitches nominally specified in the music score. They can be classified according to their apparent musical function: to help the listener ( I ) in the differentiation of different pitch and duration categories and (2) in the grouping of the tones. Apart from this, some rules serve the purpose of organizing tuning and synchronization in ensemble performance. The rules reveal striking similarities between music performance and speech; for instance final lengthening occur in both and the acoustic code used for marking of emphasis are similar. INTRODUCTION In our computer age, it is neither difficult nor rare to have computers perform music. What distinguishes these performances from man-made performances is a lack of musical expressivity. Computer-generated performances sound musically pathological. Physical correlates of musical expressivity have been identified in terms of numerous minor and major deviations from the pitches, durations, and sound levels nominally assigned to the different tones by the score. These deviations are often referred to as expressive deviations. The unmusical quality of computer-generated performances is interesting, as it seems to point to a very significant aspect of music communication. Ten years ago we started to investigate this area. The aim was to describe the principles according to which musicians distribute expressive deviations. Results from our research have been presented in detail elsewhere (Friberg, 1989; Sundberg, 1988; Sundberg, 1989; Sundberg, Friberg, & FrydCn, 1989). Once the expressive deviations have been described, the principles underlying them can be submitted to a scientific inquiry. Here, we will concentrate on two questions: what do the musicians add which is not written in the score, and why do they add this?