- the interpretation of values in tiers between the first point and the last point.

### Example

The following is a PitchTier with three points:

Between 0.10 and 0.20 seconds, the pitch rises linearly from 170 to 180 Hz, and between 0.20 and 0.45 seconds it falls linearly from 180 to 110 Hz. This is *linear interpolation*: at all times between two adjacent points, the pitch values follow the straight line that connects the two points.

(Before 0.10 seconds and after 0.45 seconds there is constant extrapolation.)

### Linear interpolation in Praat

Praat uses linear interpolation in all tiers and grids with values at time points (PitchTier, IntensityTier, DurationTier, AmplitudeTier, FormantGrid).

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