- the interpretation of values in tiers before the first point or after the last point.
The following is a PitchTier with three points:
Between 0.10 and 0.20 seconds, the pitch rises from 170 to 180 Hz, and between 0.20 and 0.45 seconds it falls from 180 to 110 Hz. This is linear interpolation.
But what happens before 0.10 seconds? There, the pitch is just 170 Hz, i.e. the value of the first pitch point. This is constant extrapolation to the left.
Likewise, after 0.45 seconds the pitch is just 110 Hz, i.e. the value of the last pitch point. This is constant extrapolation to the right.
Praat uses constant extrapolation in all tiers and grids with values at time points (PitchTier, IntensityTier, DurationTier, AmplitudeTier, FormantGrid).
© ppgb, April 25, 2008