18.5 General intonation

As there seems to be a number of intonation theories that predict F0 contours by rule (possibly using trained parameters) this module aids the external specification of such rules for a wide class of intonation theories (through primarily those that might be referred to as the ToBI group). This is designed to be multi-lingual and offer a quick way to port often pre-existing rules into Festival without writing new C++ code.

The accent prediction part uses the same mechanisms as the Simple intonation method described above, a decision tree for accent prediction, thus the tree in the variable int_accent_cart_tree is used on each syllable to predict an IntEvent.

The target part calls a specified Scheme function which returns a list of target points for a syllable. In this way any arbitrary tests may be done to produce the target points. For example here is a function which returns three target points for each syllable with an IntEvent related to it (i.e. accented syllables).

     (define (targ_func1 utt syl)
       "(targ_func1 UTT STREAMITEM)
     Returns a list of targets for the given syllable."
       (let ((start (item.feat syl 'syllable_start))
             (end (item.feat syl 'syllable_end)))
         (if (equal? (item.feat syl "R:Intonation.daughter1.name") "Accented")
             (list
              (list start 110)
              (list (/ (+ start end) 2.0) 140)
              (list end 100)))))

This function may be identified as the function to call by the following setup parameters.

     (Parameter.set 'Int_Method 'General)
     (Parameter.set 'Int_Target_Method Int_Targets_General)
     
     (set! int_general_params
           (list
            (list 'targ_func targ_func1)))