Manipulation

One of the types of objects in Praat, for changing the pitch and duration contours of a sound.

Inside a manipulation object

With Inspect, you will see the following attributes:

timeStep
the time step (or frame length) used in the pitch analysis. A common value is 0.010 seconds.
minimumPitch
the minimum pitch frequency considered in the pitch analysis. A common value is 75 hertz.
maximumPitch
the maximum pitch frequency considered in the pitch analysis. A common value is 600 hertz.

A Manipulation object also contains the following smaller objects:

1. The original Sound.
2. A PointProcess representing glottal pulses.
3. A PitchTier.
4. A DurationTier.

Analysis

When a Manipulation object is created from a sound, the following steps are performed:

1. A pitch analysis is performed on the original sound, with the method of Sound: To Pitch.... This uses the time step, minimum pitch, and maximum pitch parameters.
2. The information of the resulting pitch contour (frequency and voiced/unvoiced decisions) is used to posit glottal pulses where the original sound contains much energy. The method is the same as in Sound & Pitch: To PointProcess (cc).
3. The pitch contour is converted to a pitch tier with many points (targets), with the method of Pitch: To PitchTier.
4. An empty DurationTier is created.

Resynthesis

A Manipulation object can produce Sound input. This Sound can be computed in several ways:
overlap-add: from original sound + pulses + pitch tier + duration tier;
LPC: from LPC (from original sound) + pulses + pitch tier;
• from the pulses only, as a pulse train or hummed;
• from the pitch tier only, as a pulse train or hummed.

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© ppgb, March 16, 2003