Supported Features in VoiceXML Applications
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Speech Server supports VoiceXML application features, VoiceXML elements, and a variety of properties.
Application Features
| Description | Support Level | Standard | Note |
|---|---|---|---|
Referencing scripts dynamically |
Full |
2.1 |
|
Referencing grammars dynamically |
Full |
2.1 |
|
Recording user utterances while attempting recognition |
Full |
2.1 |
VoiceXML 2.1 extends the <field>, <initial>, <link>, <menu>, <record>, and <transfer> elements to allow the interpreter to conditionally enable recording while simultaneously gathering input from the user. |
Platform-specific commands |
Full |
The following platform-specific commands are supported: Help, Cancel, and Exit. |
|
Built-in grammars |
Full |
The following built-in grammar types are supported: Boolean, date, digits, currency, number, phone, and time. |
|
Keyword grammars |
Full |
These grammars are created using Speech Grammar Editor and comply with the W3C SRGS specification. |
|
Prompt Engine Markup Language (PEML) |
Full |
PEML is markup language that specifies the text input used by the prompt engine to produce speech output. |
|
Bridge and consultation transfers |
Bridge transfer is not supported in Speech Server. |
VoiceXML Elements
| Element | Support Level | Standard | Note |
|---|---|---|---|
<assign> |
Full |
2.0 |
|
<audio> |
Full |
2.0 |
|
<block> |
Full |
2.0 |
|
<catch> |
Full |
2.0 |
|
<choice> |
Full |
2.0 |
|
<clear> |
Full |
2.0 |
|
<data> |
Limited |
2.1 |
Ignored by Speech Server. |
<disconnect> |
Full |
2.0 |
The 2.1 namelist attribute is supported. |
<else> |
Full |
2.0 |
|
<elseif> |
Full |
2.0 |
|
<enumerate> |
Full |
2.0 |
|
<error> |
Full |
2.0 |
|
<exit> |
Full |
2.0 |
|
<field> |
Full |
2.0 |
|
<filled> |
Full |
2.0 |
|
<foreach> |
Full |
2.1 |
|
<form> |
Full |
2.0 |
|
<goto> |
Full |
2.0 |
|
<grammar> |
Full |
2.1 |
Only SRGS (Speech Recognition Grammar Specification) or CFG (context-free grammar) grammars are supported. See the following example. ABNF (Augmented Backus-Naur Form) grammars are not supported. |
<help> |
Full |
2.0 |
|
<if> |
Full |
2.0 |
|
<initial> |
Full |
2.0 |
|
<link> |
Full |
2.0 |
|
<log> |
Full |
2.0 |
|
<mark> |
Partial |
2.1 |
<mark> is recognized by Speech Server and the VoiceXML interpreter. However, it is not supported in the TIM (Telephony Interface Manager)/TIMC (Telephony Interface Manager Connector) scenario. |
<menu> |
Full |
2.0 |
|
<meta> |
Full |
2.0 |
|
<metadata> |
Full |
2.0 |
|
<noinput> |
Full |
2.0 |
|
<nomatch> |
Full |
2.0 |
|
<object> |
Limited |
2.0 |
Ignored by Speech Server; no action is taken. |
<option> |
Full |
2.0 |
|
<param> |
Full |
2.0 |
The <object> tag has limited support. |
<prompt> |
Full |
2.0 |
|
<property> |
Full |
2.1 |
The <data>-related properties have no support and are ignored by Speech Server. The <recording>-related property is supported. |
<record> |
Full |
2.0 |
|
<reprompt> |
Full |
2.0 |
|
<return> |
Full |
2.0 |
|
<script> |
Full |
2.1 |
The 2.1 srcexpr= attribute is supported. |
<subdialog> |
Full |
2.0 |
|
<submit> |
Full |
2.0 |
|
<throw> |
Full |
2.0 |
|
<transfer> |
Partial |
2.1 |
Only blind and consultation transfers are supported. Follow the 2.1 specification and use the type= attribute. |
<value> |
Full |
2.0 |
|
<var> |
Full |
2.0 |
|
<vxml> |
Full |
2.0 |
Speech Recognizer Properties
For more information about the following properties, see W3C VoiceXML 2.0 Introduction.
| Property | Support Level | Note |
|---|---|---|
confidencelevel |
Full |
Specifies the speech recognition confidence level, which is a float value from 0.0 to 1.0. Results are rejected and a nomatch event is thrown when application.lastresult$.confidence is below this threshold. A value of 0.0 means minimum confidence is needed for a recognition, and a value of 1.0 means maximum confidence is needed. The value is a Real Number Designation. The default value is 0.5. |
sensitivity |
Full |
Sets the sensitivity level. A value of 1.0 means that the speech recognizer is highly sensitive to quiet input. A value of 0.0 means it is least sensitive to noise. The value is a Real Number Designation. The default value is 0.5. |
speedsvsaccuracy |
Full |
Provides a hint specifying the desired balance of speed versus accuracy. A value of 0.0 means fastest recognition. A value of 1.0 means best accuracy. The value is a Real Number Designation. The default is value 0.5. |
completetimeout |
Full |
Specifies the length of silence required following user speech before the speech recognizer finalizes a result, either accepting it or throwing a nomatch event. The complete time-out is used when the speech is a complete match of an active grammar. By contrast, the incomplete time-out is used when the speech is an incomplete match to an active grammar. A long complete time-out value delays the result completion and therefore makes the computer's response slower. A short complete time-out can lead to an utterance being broken up inappropriately. Reasonable complete time-out values are typically in the range of 0.3 to 1.0 second. The value is a Time Designation. The default is .5 seconds. |
incompletetimeout |
Full |
Specifies the required length of silence following user speech after which a speech recognizer finalizes a result. The incomplete time-out applies when the speech prior to the silence is an incomplete match of all active grammars. In this case, when the time-out is triggered, the partial result is rejected with a nomatch event. The incomplete time-out also applies when the speech prior to the silence is a complete match of an active grammar, but where it is possible to speak further and still match the grammar. By contrast, the complete time-out is used when the speech is a complete match to an active grammar and no further words can be spoken. A long incomplete time-out value delays the result completion and therefore makes the computer's response slower. A short incomplete time-out can lead to an utterance being broken up inappropriately. The incomplete time-out is usually longer than the complete time-out to allow users to pause mid-utterance, for example, to breathe. The default is 1.0 second. |
maxspeechtimeout |
Full |
Specifies the maximum duration of user speech. If this time elapses before the user stops speaking, the maxspeechtimeout event is thrown. The value is a Time Designation. The default duration is 20 seconds. |
Generic DTMF Properties
| Property | Support Level | Note |
|---|---|---|
interdigittimeout |
Full |
The inter-digit time-out value to use when recognizing DTMF (dual tone multi-frequency) input. The value is a Time Designation. The default is 1.0 second. |
termtimeout |
Full |
The terminating time-out to use when recognizing DTMF input. The value is a Time Designation. The default value is 0. |
termchar |
Full |
The terminating DTMF character for DTMF input recognition. The default value is #. |
Prompt and Collect Properties
| Property | Support Level | Note |
|---|---|---|
bargein |
Full |
Specifies the bargein attribute for prompts. Setting this to true allows bargein by default. Setting it to false disallows bargein. The default value is true. |
bargeintype |
Full |
Sets the type of bargein to be speech or hotword. The default value is speech. |
timeout |
Full |
Specifies the time after which a noinput event is thrown by Speech Server. The value is a Time Designation. The default value is 5.0 seconds. |
Miscellaneous Properties
| Property | Support Level | Note |
|---|---|---|
inputmodes |
Full |
|
universals |
Full |
|
maxnbest |
Full |
|
maxtime |
Full |
The maximum duration to record. The value is a Time Designation. This is an attribute of the record element. The default duration is 5 minutes. |
See Also
Tasks
How to: Create a VoiceXML Application Project