loudness/fourier analysis/grain synthesis (BIGGERSTAFF THAD LEWIS )

Subject: loudness/fourier analysis/grain synthesis
Date:    Wed, 14 Dec 1994 20:46:20 -0600

First of all, I apologize for the delay on replying to those above. I've posted this to the overall list as well, thinking it might be of others interest... The original post was concerned with the question of measuring loudness perception. The "he" in my last post (that is, the author of the article I made reference to) is Barry Truax. Two articles have appeared recently in Computer Music Journal (Volume 18:2, and 18:3) which discuss among other things his involvement in granular synthesis composition, and how this work has contributed towards his understanding of loudness, pitch, timbre: sound in general. I quote the abstract of the 18:2 article: "The psychoacoustic implications of the technique [granular synthesis], such as the magnification of instantaneous resonances and the perception of increased volume, are discussed, as is compositional experience that links the inner complexity of the sound to the complexity of the external world." Volume 18:3's article consists of an interview with Truax, where, again among other things, he goes into more detail on his views of Fourier analysis and its limitations... Another article of great interest in this regard is again authored by Truax. It appears in Interface Journal (Vol. 21, 1992, pp. 29-42). It's title is "Musical Creativity and Complexity at the Threshold of the 21st Century". Again, I quote from the abstract: "The author describes a paradigm shift in which current models of sound and music are replaced by models of complexity. In terms of sound, the shift moves away from linear (e.g. Fourier) models in acoustics and parameter response models in psychoacoustics towards multi-dimensional concepts of timbre, volume, and temporal dynamic shape. In terms of composition, the shift is away from its literate and detereministic aspects, as well as the notion of art as abstract and context free. The result is a concept of music where sound and structure are integrated as well as music and context. Examples are drawn from the composer's work with granular synthesis and enviromental sound composition." This article goes into great depth concerning the limitations of "current" frameworks for assessing sound... As a particular example from this article: "It is interesting to speculate why one model, the timeless Fourier-based fixed waveform oscillator, achieved its dominant role, despite its obvious aural deficiencies, while another that corresponds more closely to the auditory system languished on the sidelines. In 1947 the British physicists Dennis Gabor proposed an 'acoustical quantum' as the fundamental unit of sound that incorporates both frequency and time because "it is our most elementary experience that sound has a time pattern as well as a frequency pattern." ...In other words, the quantum is the shortest duration of sound that will activate the auditory system. It is an event, not merely a fixed stimulus...." If any one has any comments concerning this, please forward them. The CMJ articles were my first introduction to much that is discussed in them, and I would welcome any further information/experience on this topic/approach... I am also wondering if there are any graduate progarms doing research in this or a related field, using a similar approach to Truax's... Hope this is informative, and again I welcome further enquiries/suggestions... -Thad Biggerstaff

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DAn Ellis <dpwe@ee.columbia.edu>
Electrical Engineering Dept., Columbia University