In experimental research into percussion ‘languages', an interactive computer system, the Bol Processor, has been developed by the authors to analyse the performances of expert musicians and generate its own musical items that were assessed for quality and accuracy by the informants. The problem of transferring knowledge from a human expert to a machine in this context is the focus of this paper. A prototypical grammatical inferencer named QAVAID (Question Answer Validated Analytical Inference Device, an acronym also meaning ‘grammar' in Arabic/Urdu) is described and its operation in a real experimental situation is demonstrated. The paper concludes on the nature of the knowledge acquired and the scope and limitations of a cognitive-computational approach to music.