Interpreting Spoken Input

Since the VoiceXML Forum Community Bulletin Board is increasingly besieged by spammers, going forward I’m going to cross post responses I submit there on this site so that interested parties (assuming there are any ;-)) can read them.

This response relates to the use of semantic interpretation in VoiceXML applications, something I have written on before. I hope readers find the exchange below helpful.


Is there a way to map a response to a certain value? For instance, if the user says “yes,” “sure,” or “yeah” I’d like to put 1 in the database? If the user says “no,” “nope,” or “nah” I’d put 0.


There are a couple of option open to you if all you are using is a simple yes/no grammar.

Option 1 = use the builtin “boolean” grammar type. By specifying a field type of “boolean”, an implicit grammar is created that should cover affirmative or negative responses for whataver language is being used. A boolean field returns a JavaScript string based on what the user says (e.g., yes=’true’ or no=’false’). You can convert this to a 1 or 0 using a simple if/else construct and a predefnied variable.

<var name="convert" expr="0"/>


<field name="F_1" type="boolean">
<prompt>Do you think VoiceXML rocks?</prompt>

<!-- If the user says yes, then the expression in the "cond" attribute will evaluate to true -->
<if cond="F_1">
<assign name="convert" expr="1"/>

<!-- If the preceding if statement did not execute, then expression in the cond attribute evaluated to false. User said no, so we keep our original value of 0 -->
<submit next="mypage.jsp" namelist="convert"/>


Option 2 = you can use the <tag> element with a custom yes/no grammar to return a 1 or a 0. (Check your platform vendor’s documentation on this element, as there is some variation.)

<!-- In your VoiceXML document, reference the yes/no grammar -->
<field name="F_1">
<grammar src="yesno.grxml"/>

<!-- Contents of yesno.grxml file -->
< ?xml version = "1.0"?>
<grammar xml:lang="en-US" version="1.0" root="R_1" type="application/srgs+xml" xmlns="">
<rule id="R_1">
<one -of>
<item>yes <tag>F_1=1;</tag> </item>
<item>yeah <tag>F_1=1;</tag> </item>
<item>hells yeah <tag>F_1=1;</tag> </item>
<item>yur damn skippy <tag>F_1=1;</tag> </item>
<item>no <tag>F_1=0;</tag> </item>
<item>nope <tag>F_1=0;</tag> </item>
<item>no way <tag>F_1=0';</tag> </item>
<item>hells no <tag>F_1=0;</tag> </item>


This has the effect of filling the field named “F_1” with the value specified in the <tag> when one of the grammar items is recognized. A few good links to get you started follow:

BeVocal Cafe

Voxeo Community


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