W3C home > Mailing lists > Public > w3c-wai-gl@w3.org > July to September 2005

RE: [action] VoiceXML and WCAG

From: Christophe Strobbe <christophe.strobbe@esat.kuleuven.be>
Date: Fri, 30 Sep 2005 11:07:23 +0200
Message-Id: <>
To: "Roberto Scano - IWA/HWG" <rscano@iwa-italy.org>, gramuglio@dotvocal.com
Cc: w3c-wai-gl@w3.org

Hi Fabrizio and Roberto,

Thank you for pointing out that the VoiceXML Forum has an accessibility
committee (http://www.voicexml.org/resources/accessibility.html).

At 18:30 29/09/2005, Roberto Scano wrote:
Here some note from our representative inside VoiceXML WG. Note is with >.
He is in cc.

   Level 3 Success Criteria for Guideline 1.1

   For prerecorded multimedia content, a combined transcript of captions
   and audio descriptions of video is available.

   Not applicable (multimedia).
 ><Audio> Provide a multimedia content (pre-registred file)

I don't understand this comment.
In the context of this success criterion, multimedia means combined audio
and video. Streaming video through a voice application doens't seem to
make sense. Prerecorded audio can be used, but this is already covered by
the success criteria at level 1.
Requiring a text alternative (GL 1.1 L1 SC 1-5) is reasonable because
the person whose voice is being used (in the recording) also needs this
text, so it is definitely available.

   Level 1 Success Criteria for Guideline 1.3

   1. Structures within the content can be programmatically determined.

   Until I find evidence to the contrary, a VoiceXML document must meet this
   success criterion or the voice application will not work. However, if
   VoiceXML is used to present structured text (newspaper articles, any
   non-fiction or fiction), there are no elements to mark headings, quotes,
   etcetera. There is even no element for descriptive titles (see discussion
   of Guideline 2.4 Level 2 SC 3 below).

 >If the rule is related only to a presentation feeling.. SSML with
<emphasis>  can be very usefull, even quotes can be transled in <break>

While writing these notes, I considered <emphasis>, <break> and most other
SSML elements (with the exception of <meta>, <metadata>, <p> and <s>) as
presentational elements, not structural elements. You can use SSML
to markup the types of (structured) text I listed, but that would be
like abusing presentational HTML markup to fake structure
(e.g. using big, bold text instead of <hx>).
To my understanding, VoiceXML elements do not represent structure in
the sense of document structure, but dialogue/interaction "structure",
and without the proper use of these structures (prompts, forms, menus,
nomatch, etc.) a VoiceXML document will not work properly. This is where
HTML differs from VoiceXML: if you throw out structure and rely purely
on presentational elements, an HTML document will still work for a large
percentage of the population.

   Level 1 Success Criteria for Guideline 2.2
   1. Content is designed so that time-outs are not an essential part of
   interaction, or .

   However, the use of this feature does not meet any of the bullet points of
   this success criterion. I am not sure if it is possible to store the
   timeout value in a variable, then reference this variable in the timeout
   attribute and increment it in <noinput>, or to prompt the user for a new 

 > In a dialog prompts have to be designed, and u can include for example the
 >In tapered prompts for example:
 >       <form id="one">
                 <field name="one">
                         <prompt timeout="120s">First prompt</prompt>
                         <noinput count="1">
                                 <prompt timeout="150s">Second
                         <noinput count="2">
                                 <prompt timeout="170s">Third prompt</prompt>
the user is allowed to deactivate the time-out or ..
 > But.. there is also a timeout property, so.. it's possible to ask to user
if it prefer to have or not timeout, and then set the property, and turn-off
the timeout attribute

It is not obvious how you can turn off timeout: section 6.3.4 states that the
default value for timeout is platform-dependent. To my understanding, this
means that some platforms (may) provide there own timeout value, while others
don't provide a value, and that both categories of platforms conform to the
If you could provide example code for turning off a timeout, especially for
platforms that provide their onw timeout value, that would be great.

I delved somewhat deeper and noticed that this success criterion does not only
apply to the timeout attribute, but also to the maxtime and finalsilence
attributes of the record element, and probably also to the maxspeechtimeout
property (one of the generic speech recognizer properties).

   2. Moving or time-based content can be paused by the user.
   If a prompt does not specify a noinput timeout, the application uses a
   platform-specific default timeout. It is not obvious how content can be
   paused by the user.

 > for long prompt, for example: a mail reader, yoi can set <mark> tag ..
even if is not well supported at this time.

I had not thought of this. The problem here is that <mark> is in SSML
but regarding its purpose in VoiceXML, the VoiceXML specification
says that it is "ignored by VoiceXML platforms" (section 4.1.1: Speech

   Guideline 2.5 Help users avoid mistakes and make it easy to correct them

   Level 2 Success Criteria for Guideline 2.5

   1. If an input error is detected, the error is identified and provided to
   the user in text.
   It is not possible to detect errors, only that inputs don't match grammars,
   so VoiceXML applications don't need to do anthing to meet this criterion.

 > there are, more than <noinput> or <nomatch>, other errors, for example the
resource is not available, etc..
 > these errors can be catched by <catch> element and a can be sumbit a

Yes, there are other errors, but are these input errors? If a resource is not
available, that is not an input error. (In previous drafts of WCAG, input
errors were called "user errors".)
When a resource is not available, the user should be notified, but WCAG has
no guideline on this: it is a usability issue rather than an accessibility

Thanks for the input and feedback. I'll update the document some time next 
I was considering sending it to www-voice@w3.org and to the VoiceXML 
of which I am still a member.


Christophe Strobbe

Christophe Strobbe
K.U.Leuven - Departement of Electrical Engineering - Research Group on 
Document Architectures
Kasteelpark Arenberg 10 - 3001 Leuven-Heverlee - BELGIUM
tel: +32 16 32 85 51

Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
Received on Friday, 30 September 2005 09:08:42 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 16 January 2018 15:33:56 UTC