Real Time Automatic Harmonisation (in French)

Giordano Cabra
University of Paris 6, Paris, France (July, 2008)


We define real-time automatic harmonization systems (HATR in french) as computer programs that accompany a possibly improvised melody, by finding an appropriate harmony to be applied to a rhythmic pattern. In a real-time harmonization situation, besides performance and scope constraints, the system and the user are in symbiosis. Consequently, the system incorporates elements from accompaniment, composition, and improvisation, remaining a challenging project, not only for its complexity but also for the lack of solid references in the scientific literature.

In this work, we propose some extensions to techniques developed in the recent past by the music information retrieval (MIR) community, in order to create programs able to work directly with audio signals. We have performed a series of experiments, which allowed us to systematize the main parameters involved in the development of such systems. This systematization led us to the construction of a HATR framework to explore possible solutions, instead of individual applications.

We compared the applications implemented with this framework by an objective measure as well as by a human subjective evaluation. This thesis presents the pros and cons of each solution, and estimates its musical level by comparing it to real musicians. The results of these experiments show that a simple solution may overcome complex ones. Other experiments have been made to test the robustness and scalability of the framework solutions.

Finally, the technology we constructed has been tested in novel situations, in order to explore possibilities of future work.

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