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What is Timbre?

"the distinctive property of a complex sound"

"timbre refers to the perceptual quality of sounds"

"timbre is that attribute of sensation in terms of which a
listener can judge that two sounds having the same loudness
and pitch are dissimilar"

"the timbre of an instrument is the type of sound it makes"

"everything that is not loudness, pitch, or spatial perception"

         So often used, but often so ambiguously defined. Timbre like pitch is tied to human perception, thus it is inherently subjective in nature. The last definition above is the most correct.  Timbre is defined in terms of what it is not.  It is all the qualities left over after describing pitch and loudness.   Timbre is often determined by the harmonic content and dynamic character of the sound; it is a psychoacoustic property. Scales to rate or distinguish timbre have been developed and use terms like sharp & dull,compact & scattered, bright & dark, hollow & full. Although these terms do have meaningful correlations to sound, they are still very subjective and do not offer a systematic method for timbre classification.
         The speech counterpart of musical timbre is the phoneme, which often carries some of the same ambiguity as the term timbre. Merriam Webster defines it as "An abstract unit of language that is clearly distinguished from a set of similar sounds corresponding to it." So the phoneme like timbre involves distinguising "similar" sounds. However, the phoneme has been extensively studied and described by linguists, and offers a highly developed and systematic description of vocal sound. The English cardinal vowels are only a faction of the distinct set of phonemes that make up the English language.
         It would be nice to have a similar system to describe musical timbre. In this project from music 255 at CCRMA, based on the ideas of Professor Jonathan Berger, I propose a system of musical timbre classification based on english vocal phonemes. Through the use of formant analysis, acoustic instrument sounds and combinations of instrument sounds can be classified on a vowel scale in a very analytical way. This provides a platform for concise timbre description and comparison. The fricative vocal sounds provide a system for describing attack, and non-tonal musical elements.
         This system can be used as a tool for teaching orchestration. Orchestration is largely concerned with the timbral combination of instrumental and sometimes electronic sounds. The phoneme classification system provides a platform for scientific orchestrational analysis. Also, it offers teachers a well-defined method for evaluating and critiquing student work.

  © 2003 John McCarty - mccarty@stanford.edu