Pitch contours

In linguistics, speech synthesis, and music, the pitch contour of a sound is a function or curve that tracks the perceived pitch of the sound over time. Because it deals with complex sounds involving many pitches, it is necessarily a relative measure that relates the frequency function at one point in time to the frequency function at a later point.

It is fundamental to the linguistic concept of tone, where the pitch or change in pitch of a speech unit over time affects the semantic meaning of a sound. It also indicates intonation in pitch accent languages.

One of the primary challenges in speech synthesis technology, particularly for Western languages, is to create a natural-sounding pitch contour for the utterance as a whole. Unnatural pitch contours result in synthesis that sounds "lifeless" or "emotionless" to human listeners, a feature that has become a stereotype of speech synthesis in popular culture.

In music, the pitch contour focuses on the relative change in pitch over time of a primary sequence of played notes. The same contour can be transposed without losing its essential relative qualities, such as sudden changes in pitch or a pitch that rises or falls over time.

Pure tones have a clear pitch, but complex sounds such as speech and music typically have intense peaks at many different frequencies. Nevertheless, by establishing a fixed reference point in the frequency function of a complex sound, and then observing the movement of this reference point as the function translates, one can generate a meaningful pitch contour consistent with human experience.

For example, the vowel e has two primary formants, one peaking between 400 and 600 Hz and one between 2200 and 2600 Hz. When a person speaks a sentence involving multiple e sounds, the peaks will shift within these ranges, and the movement of the peaks between two instances establishes the difference in their values on the pitch contour.

Music bibliography

 * Cogan and Escot (1976). Sonic Design: The Nature of Sound and Music. (Englewood Cliffs, NJ: Prentice-Hall.
 * Friedmann, "A Methodology for the Discussion of Contour: Its Application to Schoenberg's Music," Journal of Music Theory 29 (1985): 223-48.
 * Morris, Composition with Pitch-Classes: A Theory of Compositional Design (New Haven and London: Yale University Press, 1987)
 * Polansky, "Morphological Metrics: An Introduction to a Theory of Formal Distances" in Proceedings of the International Computer Music Conference (San Francisco: Computer Music Association, 1987).


 * Larry Polansky; Richard Bassein (1992). "Possible and Impossible Melody: Some Formal Aspects of Contour", Journal of Music Theory, Vol. 36, No. 2. (Autumn, 1992), pp. 259-284.

Ethnomusicology

 * Mieczyslaw Kolinski, "The Structure of Melodic Movement: A New Method of Analysis," Studies in Ethnomusicology 2 (1965): 96-120
 * Charles R. Adams, "Melodic Contour Typology," Ethnomusicology 20 (1976): 179- 215.
 * Charles Seeger, "On the Moods of a Music-Logic." Journal of the American Musicology Society 8 (1960): 224-61.
 * Elizabeth West Marvin, "A Generalization of Contour Theory to Diverse Musical Spaces: Analytical Applications to the Music of Dallapiccola and Stockhausen" in Musical Pluralism: Aspects of Aesthetics and Structure Since 1945 (forthcoming). Contains review of these and earlier articles.