Festival Speech Synthesis System: - Speech Resource Pages

19.3 Klatt durations Klatt rules from book.
19.4 CART durations Tree based durations
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19.1 Default durations
If parameter Duration_Method is set to Default, the simplest duration model is used. All segments are 100
milliseconds (this can be modified by Duration_Stretch, and/or the localised Token related dur_stretch
feature).
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19.2 Average durations
If parameter Duration_Method is set to Averages then segmental durations are set to their averages. The
variable phoneme_durations should be an a-list of phones and averages in seconds. The file
`lib/mrpa_durs.scm' has an example for the mrpa phoneset.
If a segment is found that does not appear in the list a default duration of 0.1 seconds is assigned, and a warning
message generated.
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19.3 Klatt durations
If parameter Duration_Method is set to Klatt the duration rules from the Klatt book (allen87, chapter 9). This
method requires minimum and inherent durations for each phoneme in the phoneset. This information is held in the
variable duration_klatt_params. Each member of this list is a three-tuple, of phone name, inherent duration
and minimum duration. An example for the mrpa phoneset is in `lib/klatt_durs.scm'.
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19.4 CART durations
Two very similar methods of duration prediction by CART tree are supported. The first, used when parameter
Duration_Method is Tree simply predicts durations directly for each segment. The tree is set in the variable
duration_cart_tree.
The second, which seems to give better results, is used when parameter Duration_Method is Tree_ZScores.
In this second model the tree predicts zscores (number of standard deviations from the mean) rather than duration
directly. (This follows campbell91, but we don't deal in syllable durations here.) This method requires means and
standard deviations for each phone. The variable duration_cart_tree should contain the zscore prediction tree
and the variable duration_ph_info should contain a list of phone, mean duration, and standard deviation for
each phone in the phoneset.
An example tree trained from 460 sentences spoken by Gordon is in `lib/gswdurtreeZ'. Phone means and
standard deviations are in `lib/gsw_durs.scm'.