Matter of Tim(br)e:
Unveiling the occult of the sensory perception of Timbre
Rodrigo Tascon
Timbre, amongst the different perceptual attributes of sound (i.e. pitch, duration, amplitude etc.), is certainly the most mysterious, enigmatic and compelling of them all. The word itself, cryptically bears a number of different meanings in different disciplines, and the concept is usually defined in terms of what it is not: “Timbre is that attribute of auditory sensation in terms of which a listener can judge that two sounds similarly presented and having the same loudness and pitch are dissimilar.” (American National Standards Institute 1960).
Timbre also appears to be considered as a misleading term, as the concept in question is difficult to define with any precision, and is usually described as a complex phenomenon, which is poorly understood and ambiguously defined. In general terms, the physical and psychological correlates of Timbre have not yet been determined. This simple, puzzling word encloses a group of complex set of auditory attributes as well as a number of musical and psychological matters; whatever constitutes the percept of Timbre and how we perceive it remains, in terms of our understanding, occult. However, our experience towards the perception of timbre seems straightforward, that is, we can easily distinguish a piano from a saxophone, furthermore, we can still recognize a saxophone weather it is playing in a concert hall, open doors or on the radio.
So, what is it about Timbre that we find so compelling? It seems of human nature to feel seduced by the unknown, but it’s also its complex chaotic behavior that appeals to our ears: we find much more ‘musical’ the chaotic sound of a violin than a computer generated steady pure sine tone. In a way, because it’s intrinsically related to the rest of parameters, and also because, although different from Time, it’s inseparable from it. Furthermore, cognitive psychology, in terms of what is referred to as ‘musical experience’, divides neural processes within certain ‘time frames’, and places the percept of Timbre in a particular time scale described as ‘fusion threshold’. That is, when individual events occur in a very short time, the mind shifts the way it processes sounds and ‘fuses’ events’. “At a rate a rate of 20 events per second (50 msec per event), the pattern of events for all practical purposes is a waveform, and its individual events fuse together to form a single higher-level event” (Snyder 2000). The result, given a particular noise-periodicity rate, becomes Timbre. In other words, there exists a continuum between Rhythm and Timbre, that is the discernment of individual events that constitute timbre; it’s only a matter of time: “The distinction between note, frequency, timbre and harmony and rhythm, becomes fuzzy or even irrelevant.” (D. Pressnizter, McAdams, S. 2000)
This paper is not an attempt to shed new light on the subject nor to be an exhaustive or critical review on the subject, but rather to clarify and to put forward the fundamental variables for its prediction according to recent studies. The main reason for this is obviously to gain control within sound synthesis, but also to familiarize composers with the theoretical and technical boundaries encountered when dealing and constructing upon the percept of Timbre; to put it in Risset’s words:
“[…] what we call the psychoacoustic problem: to use sound synthesis effectively, one most resort to some sort of psychoacoustic knowledge or know-how on the relation between the physical structure – which the composer controls when he specifies the synthesis data – and aural effect – which determines the musical impact.”
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To download full article go to: http://files-upload.com/files/661180/CNQ- Winter 2007, Tascon "Matter of Tim(br)e".pdf
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