Speech intonation is the pattern of pitch variation across an utterance. Its acoustic description commonly uses a pitch contour, tracking the estimated fundamental frequency through voiced portions of speech. The pitch contour describes one component of prosody; it does not by itself encode every distinction conveyed by emphasis, pauses or timing.
To investigate it, record the same phrase with different intended emphasis, then align the recordings by their words and compare the pitch contours. Inspect the underlying waveform as well as the automatic estimate: a tracking error can resemble an abrupt jump. The analysis range matters, and a low pitch floor requires a longer time window, trading the ability to detect low fundamental frequencies against the resolution of rapid changes.[ref]
An estimated fundamental frequency should not be read as a measured vocal oscillation during a genuinely unvoiced interval. Nor does a rise have a universal meaning independently of the language and conversational setting.
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