Pitch contour
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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.
[edit] See also
[edit] External links
- Reuven Tsur. Phonetic Cues and Dramatic Function Artistic Recitation of Metered Speech. Tel Aviv University. A research article containing images illustrating many specific examples of pitch contours for recited poetry.
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