[Architecture] Transformations for speech rate NVDA [%] <=> espeak [wpm]

Claudia Loitsch claudia.loitsch at tu-dresden.de
Thu Mar 7 08:09:53 EST 2013

Hi all,

If the discussion regarding transformations of speech rate is still 
open, the following information could be helpful:

Transformation depends on the min and max values defined in the 
configuration file of espeak [1]. Per default it seems that min = 80 and 
max = 390. NVDA supports a scale between min = 0% and max 100%. NVDA 
uses the following both Transformations:

Transformation 1 - *percentToParam()* [2]
Convert a percentage to a raw parameter value given the current 
percentage and the minimum and maximum raw parameter values
     int(round(float(percent) / 100 * (max - min) + min))

Transformation 2 - *paramToPercent() *[3]
Convert a raw parameter value to a percentage given the current (int), 
minimum (int) and maximum (int) raw values:
     int(round(float(current - min) / (max - min) * 100))

You can test these transformations with the help of the phyton console 
of nvda (context menu => extras) by using the following commands:
speech.getSynth()._paramToPercent(100, 80, 390)
speech.getSynth()._percentToParam(100, 80, 390)

Further more, booster multipler ist set to 3 [4].

Best regards,



Dipl.-Medieninf. Claudia Loitsch

Technische Universität Dresden
Institut für Angewandte Informatik
Professur Mensch-Computer Interaktion

Tel.: 0351/463 42025
Fax: 0351/463 38491

E-Mail: claudia.loitsch at tu-dresden.de

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