A query to ask the selected tier object (DurationTier, IntensityTier, PitchTier) which point is nearest to, but no later than, the specified time.
This query returns the index of the point with the highest time less than or equal to Time. It is undefined if there are no points. It is 0 (offleft) if the specified time is less than the time of the first point.
© ppgb, December 30, 2010