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We have developed a simple algebraic approach to music description and composition called Haskore. In this framework, musical objects consist of primitive notions such as notes and rests, operations to transform musical objects such as transpose and tempo-scaling, and operations to combine musical objects to form more complex ones, such as concurrent and sequential composition. When these simple notions are embedded into a functional language such as Haskell, rather complex musical relationships can be expressed clearly and succinctly. Exploiting the algebraic properties of Haskore, we have furthermore defined a notion of literal performance (devoid of articulation) through which observationally equivalent musical objects can be determined. With this basis many useful properties can be proved, such as commutative, associative, and distributive properties of various operators. An algebra of music thus surfaces. 1 Introduction Traditional music notation (often called common practice no...

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The MPEG-4 standard, which will be published in October 1998, contains extensive provisions for sound synthesis as well as traditional methods of audio compression. At the heart of MPEG-4 Structured Audio, the sound-synthesis framework, is a new music-synthesis language called SAOL. This language, based on the Music-N model, is specified and defined fully in the MPEG-4 International Standard; a real-time implementation must be embedded in any device conforming to the full MPEG-4 Audio standard. In this paper, the structure and capabilities of SAOL are discussed, especially in comparison with other music languages. A discussion of the role of international standardization in the future development of computer-music tools is also presented.

Sounds are often the result of motions of virtual objects in a virtual environment. Therefore, sounds and the motions that caused them should be treated in an integrated way. When sounds and motions do not have the proper correspondence, the resultant confusion can lessen the effects of each. In this paper, we present an integrated system for modeling, synchronizing, and rendering sounds for virtual environments. The key idea of the system is the use of a functional representation of sounds, called timbre trees. This representation is used to model sounds that are parameterizable. These parameters can then be mapped to the parameters associated with the motions of objects in the environment. This mapping allows the correspondence of motions and sounds in the environment. Representing arbitrary sounds using timbre trees is a difficult process that we do not address in this paper. We describe approaches for creating some timbre trees including the use of genetic algorithms. Rendering the...

Two systems are reviewed than perform automatic music transcription. The first perform monophonic transcription using an autocorrelation pitch tracker. The algorithm takes advantage of some heuristic parameters related to the similarity between image and sound in the collector. The detection is correct between notes B1 to E6 and further timbre analysis will provide the necessary parameters to reproduce a similar copy of the original sound. The second system is able to analyse simple polyphonic tracks. It is composed of a blackboard system, receiving its input from a segmentation routine in the form of an averaged STFT matrix. The blackboard contents an hypotheses database, an scheduler and knowledge sources, one of which is a neural network chord recogniser with the ability to reconfigure the operation of the system, allowing it to output more than one note hypothesis at the time. Some examples are provided to illustrate the performance and the weaknesses of the current implementation. Next steps for further development are defined.

. While previous generations of the MPEG multimedia standard have focused primarily on coding and transmission of content digitally sampled from the real world, MPEG-4 contains extensive support for structured, synthetic and synthetic/natural hybrid coding methods. An overview is presented of the "Structured Audio" and "AudioBIFS" components of MPEG-4, which enable the description of synthetic soundtracks, musical scores, and effects algorithms and the compositing, manipulation, and synchronization of real and synthetic audio sources. A discussion of the separation of functionality between the systems layer and the audio toolset of MPEG-4 is presented, and prospects for efficient DSP-based implementations are discussed.

this paper I assume that the reader is familar with the basics of functional programming and Haskell in particular. If not, I encourage reading at least A Gentle Introduction to Haskell [HF92] before proceeding. I also assume some familiarity with equational reasoning; an excellent introductory text on this is [BW88]. 2 The Architecture of Haskore

Structured-audio techniques are a recent development in audio coding that develop new connections between the existing practices of audio synthesis and audio compression. A theoretical basis for this coding model is presented, grounded in information theory and Kolmogorov complexity theory. It is demonstrated that algorithmic structured audio can provide higher compression ratios than other techniques for many audio signals and proved rigorously that it can provide compression at least as good as every other technique (up to a constant term) for every audio signal. The MPEG-4 Structured Audio standard is the first practical application of algorithmic coding theory. It points the direction toward a new paradigm of generalized audio coding, in which structured-audio coding subsumes all other audio-coding techniques. Generalized audio coding offers new marketplace models that enable advances in compression technology to be rapidly leveraged toward the solution of problems in audio coding. Index Terms---Audio compression, MPEG-4, sound synthesis, structured audio. I.

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