IntervalTier

IntervalTier is a type of tier used within the TextGrid data structure in Praat for annotating continuous time with labeled intervals. It is designed to represent segments of audio by their temporal boundaries and an associated label.

An IntervalTier consists of an ordered list of intervals. Each interval has a start time (xmin), an end time (xmax), and a text label. The tier itself has a name and spans a defined time range, typically corresponding to the analyzed audio. Intervals are arranged sequentially, and adjacent intervals may share boundary points.

Common uses include segmenting speech into phonetic units (such as phonemes or allophones), words, syllables, or events like pauses and breaths. Interval labels can be short or long, and can be used for transcription, timing alignment with an audio waveform, or linguistic analysis.

In the TextGrid file format, an IntervalTier is saved with its name, xmin, xmax, and the list of intervals with their xmin, xmax, and text. Editing tools allow adding, removing, splitting, merging, and re-timing intervals to refine alignment with audio or transcripts. Intervals can be relabeled without altering their time boundaries, and boundaries can be adjusted to improve precision.

Relation to other tiers: a TextGrid may contain multiple tiers of type IntervalTier as well as tiers of type PointProcess for timestamped events. All tiers share a common time axis, enabling cross-tier alignment and comparative analysis. IntervalTier is a core element for structured, time-aligned annotation in Praat workflows.