Phrasify: method

[Verity S]

In the Festival manual, it says that the Phrasify function can use either CARTs or probabilistic methods to assign break strength at word boundaries. Which of these is used as the default? Is there any way of checking which method Festival is using?

[Simon]

The default is the hand-crafted CART. You can inspect this classification tree thus:

festival> phrase_cart_tree 

which should give something like:

((lisp_token_end_punc in ("?" "." ":"))
 ((BB))
 ((lisp_token_end_punc in ("'" "\"" "," ";"))
  ((B))
  ((n.name is 0) ((BB)) ((NB)))))

and if you draw that as a tree, you’ll see that the punctuation symbols

? . :

all lead to a Big Break (BB), and that the symbols

' " , ;

all lead to a Break (B) and otherwise there is No Break (NB) unless we reach the end of the input text, in which case a BB is placed even if there is no sentence-final punctuation.

[Alexandra S]

Is there a command to modify the method used by Festival to prob_models?

[Simon]

It is not expected for this assignment to modify the method used by Festival for any steps in the pipeline, such as prob_models. The combination of which methods are used for each part of the pipeline is part of the voice definition and it won’t always make sense to modify one method in isolation (e.g., a subsequent step in the pipeline might be expecting a specific relation to be created by a preceding step).

[Joseph M]

Is there a command to query Festival as to which ‘Phrase_Method’ it is using?
Per the manual:
“There are two methods for predicting phrase breaks in Festival, one simple and one sophisticated. These two methods are selected through the parameter Phrase_Method…”

Based on my testing, it seems pretty clear that its using the ‘simple’ method, the CART which decides based on punctuation existence/type. And the manual implies that it must select one method or the other. But if I could query the Phrase_Method parameter, I could know for sure. How does one query a parameter??

[Simon]

To query a variable in Scheme, just type it’s name at the Festival prompt, without any parentheses. If you get “unbound variable” that means the variable is not set, so the method will be the built-in default (in this case, the hand-crafted CART).

[Etienne D]

I can’t seem to find what phrase_score means:

id _52 ; name ordinary ; pos_index 6 ; pos_index_score 0 ; pos jj ; phr_pos j ; phrase_score -3.69733 ; pbreak_index 1 ; pbreak_index_score 0 ; pbreak NB ;

[Simon]

This is an internal feature and you don’t need to understand what it means. The key phrase-level feature on the example above is “NB”, meaning “no break”.

[Author]

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