The Speech API needs support for event listeners for synthesis events

I'm the VP of Engineering at Benetech, the nonprofit behind Bookshare ( - the world's largest library of accessible ebooks for people with print disabilities (e.g. blind, dyslexic, cerebral palsy).

Over 70% of our 200K users have learning disabilities, such as dyslexia, and need synchronized highlighting of words as they are being spoken by a TTS engine.  We are planning to integrate the Google Chrome specific TTS APIs into the open source Readium ( EPUB 3 ebook reader to fulfill this use case in a web environment.

To validate market acceptance of this use case, below are examples of vendors to the dyslexic community, which have implemented this synchronized word-level highlighting capability in their applications:

Don Johnston: ReadOut:Loud -
Bookshare/Shinano: Read2Go -
textHELP: Read&Write Gold -
Freedom Scientific: WYNN -
Levelware: InDAISY -

To implement such features in a web application, the TTS engine needs to be able to support JS based synthesized event handlers.  Google implemented a callback mechanism in their Chrome TTS APIs by supporting an event handler as part of the speak() method (  The callbacks tied to synthesis events are ideally at the word level or triggered off SSML markers.

You can see some demo's of this capability at the following links: (install extension in Chrome via .crx download) (the FLITE voice supports callbacks, so install that first

I would highly urge that the Speech API be extended with these capabilities, so that our dyslexic users are not limited to Google Chrome for web based reading and so that the general dyslexic community can benefit from this technology in other web based applications.



Gerardo Capiel
VP of Engineering, Benetech<>
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Received on Thursday, 3 May 2012 23:54:14 UTC