Internet Engineering: VoiceXML Ali Kamandi Sharif University of - - PowerPoint PPT Presentation

Internet Engineering: VoiceXML

Ali Kamandi Sharif University of Technology Fall 2007 kamandi@ce.sharif.edu

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What Is VoiceXML?

VoiceXML, or VXML, is a markup language

like HTML.

The difference:

HTML is rendered by your Web browser to format

content and user-input forms;

VoiceXML is rendered by a voice browser.

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User Interaction

Your application can speak to the user via

synthesized speech prerecorded audio files.

Your software can receive input from the user

via

speech the tones from their telephone keypad.

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How to Make Your Content Telephone-Accessible

Rent a telephone line and run commercial

voice recognition software and text-to-speech (TTS) conversion software.

VoiceXML revolution There are free VoiceXML gateways, such as:

BeVocal (http://www.bevocal.com), Voxeo (http://www.voxeo.com), and VoiceGenie (http://www.voicegenie.com).

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VoiceXML

These gateways take VoiceXML pages from

your Web server and read them to your user. If your application needs input from the user, the gateway will interpret the incoming response and pass that response to your server in a way that your software can understand.

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VoiceXML

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VoiceXML

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VoiceXML Basics

<?xml version="1.0"?> <vxml version="2.0"> <form> <block> <audio>Hello, World</audio> </block> </form> </vxml>

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VoiceXML Basics (2)

Within that is a <form>, which can either be

an interactive element-requesting input from the user-or informational.

You can have as many forms as you want

within a VoiceXML document.

A <block> is a container for your executables,

meaning that all your tags that make your application do something, such as <audio>, <goto>,…

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VoiceXML Basics (3)

<audio>text</audio> will read the text with a TTS converter,

whereas

<audio src="wav_file_URL"/> will play a prerecorded .wav audio file.

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More VoiceXML

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More VoiceXML

<?xml version="1.0"?> <vxml version="2.0"> <form id="animal_questionnaire"> <field name="favorite_animal"> <prompt> <audio>Which do you like better, dogs or cats?</audio> </prompt> <grammar> <![CDATA[ [ [dog dogs] {<option "dogs">} [cat cats] {<option "cats">} ] ]]> </grammar>

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More VoiceXML (2)

<!-- if the user gave a valid response, the filled block is executed. --> <filled> <if cond="favorite_animal == ‘dogs’"> <goto next="#popular_dog_facts"/> <else/> <goto expr="‘psychological_evaluation.cgi?affliction=’+ favorite_animal"/> </if> </filled>

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More VoiceXML (3)

<!-- if the user responded but it didn’t match the grammar, the nomatch block is executed --> <nomatch> I’m sorry, I didn’t understand what you said. <reprompt/> </nomatch>

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More VoiceXML (4)

<!-- if there is no response for a few seconds, the noinput block is executed --> <noinput> I’m sorry, I didn’t hear you. <reprompt/> </noinput> </field> </form> <!-- additional forms can go here --> </vxml>

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Barge-in

Normally the user does not have to wait for

the prompt to finish before speaking. Instead, he can “barge in” and speak a response at any time. <prompt bargein="false"> <audio src="advertisement.wav"> </prompt>

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Speech Timeouts

If a user does not speak after hearing a

prompt, the interpreter will generate a timeout and execute the <noinput> event handler, if there is one.

<property name="timeout" value="10">

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Grammar Format

In VoiceXML 1.0, the W3C did not specify the

grammar format, allowing each Voice-XML platform to implement grammars as they chose.

In VoiceXML 2.0, each platform is required to

implement the XML format of the W3C’s Speech Recognition Grammar Format (SRGF),

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Mobile versus Voice Applications

Hard to use in noisy environment Works well in noisy environment Speech or keypad input User-input with uncomfortable keypads Can be used with any phone Requires browser-enabled telephones VoiceXML Mobile Browser

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Mobile versus Voice Applications

You only need to develop

• ne version of your

software You need to develop versions of your software for a variety of mobile gateways Users can only say predefined phrases User can enter arbitrary information Works poorly for giving the user long lists of information Works well for displaying long list of information VoiceXML Mobile Browser

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Syntax in HTML & VoiceXML

Compared to HTML, VoiceXML is much

stricter about using correct syntax.

In HTML

writing attribute values without quotes

• mitting the ending tag of a container

In VoiceXML, you must use proper syntax in

all documents.

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Beyond VoiceXML: Conversational Speech

You Will it rain tomorrow in Boston? JUPITER To my knowledge, the forecast

calls for no rain tomorrow in Boston.

You What about Detroit? JUPITER To my knowledge, the forecast

calls for no rain tomorrow in Detroit.

• Assumed that you were still interested in

rain when asking about Detroit, context carried over from the Boston question.

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References

Chapter 10:

Software Engineering for Internet Applications

by Eve Andersson, Philip Greenspun, and Andrew Grumet; The MIT Press Cambridge, Massachusetts London, England, 2006.