In a society filled with individuals claiming ownership of new ideas, it is surprising to note how modest the reaction was to our ‘call for papers’ for this issue, which was to be primarily based on the theme, ‘Breaking the Boundaries’. Perhaps this has to do with the number of people who believe that the new millennium will commence in January 2001. We have chosen two submissions to include in Volume 4(3) of Organised Sound. Barry Truax presents his thoughts on the current position of the electroacoustic community in the form of a letter to a twenty-five year old electroacoustic composer which highlights paradigm shifts that he sees evolving. Laurie Spiegel's ‘Music as mirror of mind’ describes another paradigm shift towards new musical models based on psychoacoustics, cognitive studies and subjective auditory experience.

This paper postulates that the analysis of MIDI data allows for the statistical analysis of motion in music, in particular, the kinematic analysis of motion curves in music. The paper deals with the analysis of the kinematic motion components within music, specifically music velocity (i.e. tempo) and music acceleration/deceleration (i.e. tempo change), based upon Truslit's definition of the predominant up–down motion types in music (1938). Thus, the variables of music velocity and acceleration are mathematically defined and extracted from MIDI encodings. Analysis of music velocity indicates that the differing motion types have specific and consistent velocity profiles, and that these profiles can be expressed mathematically and analysed statistically. In particular, the paper focuses on the open motion curve fit, relating the open motion velocity curve to the beta distribution. Analysis of acceleration within music suggests that music acceleration is not constant in nature, implying that theories of linear velocity are inaccurate models. Hence, it is suggested that MIDI data analysis allows for the statistical exploration into music kinematics and the motion curves within music.

So, this field we call electroacoustic music is celebrating its first half century, just as I did recently. While I cannot say that I actually grew up with this music, I discovered it in my early twenties (1969), and so I have participated in a good twenty-five years of its development. I have also heard a lot about the previous twenty-five years, often from the practitioners themselves, many of whom have unfortunately passed away in the meantime. With any luck I may still have another twenty-five years, and then you will be in my place now, and I wonder what choices you will have made, and what you will be writing to the next generation?

Hierarchical and other historically dominant models of perceived musical organisation are increasingly inapplicable to new musical processes and repertoire. The next major paradigm shift for music models, structures and concepts, perhaps comparable in importance to that in which polyphony gave way to homophony, may be a shift of emphasis from means of acoustic production and the nature of sound per se to new musical models based on psychoacoustics, cognitive studies and subjective auditory experience.

Music acoustics research can provide support in terms of objective knowledge to further the rapidly developing areas of music technology and audio processing. This is illustrated by three examples taken from current projects at KTH. One concerns the improvement in quality of sound reproduction systems over the last century. A test, where expert listeners rated the year of recordings of different ages, demonstrated that significant advances were made between 1950 and 1970, while development was rather modest before and after this period. The second example investigates the secrets of timbral beauty. Acoustic analyses of recordings of an international opera tenor and a singer with an extremely unpleasant voice shed some light on the basic requirements of good vocal timbre. The unpleasant voice is found to suffer from pressed phonation, lack of a singer's formant, irregular vibrato and insufficient pitch accuracy. The third example elucidates tuning and phrasing differences between deadpan performances of MIDI files played on synthesizers and performances by musicians on real instruments. The examples suggest that future development in the areas of music technology and audio processing may gain considerably from a close interaction with music acoustics research.

We present a novel efficient algorithm for scaling the frequency content of an audio signal by any desired factor in the range 0.5 (minus one octave) to 2.0 (plus one octave) enabling a recording to be played in any desired key without affecting the tempo. The algorithm uses an adaptive overlap-add (AOLA) technique to realise the desired frequency scaling without affecting the duration. Informal listening tests show output quality equal to that of a conventional overlap-add algorithm used in many commercially available systems, but offering significant computational saving relative to that algorithm. The algorithm can also be used to simultaneously change both the tempo and key of a recording.

Existing audio tools handle the increasing amount of computer audio data inadequately. The typical tape-recorder paradigm for audio interfaces is inflexible and time consuming, especially for large data sets. On the other hand, completely automatic audio analysis and annotation is impossible using current techniques. Alternative solutions are semi-automatic user interfaces that let users interact with sound in flexible ways based on content. This approach offers significant advantages over manual browsing, annotation and retrieval. Furthermore, it can be implemented using existing techniques for audio content analysis in restricted domains. This paper describes MARSYAS, a framework for experimenting, evaluating and integrating such techniques. As a test for the architecture, some recently proposed techniques have been implemented and tested. In addition, a new method for temporal segmentation based on audio texture is described. This method is combined with audio analysis techniques and used for hierarchical browsing, classification and annotation of audio files.