Speech Synthesis Markup Language (SSML) is an
XML
Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing data. It defines a set of rules for encoding electronic document, documents in a format that is both human-readable and Machine-r ...
-based
markup language
A markup language is a Encoding, text-encoding system which specifies the structure and formatting of a document and potentially the relationships among its parts. Markup can control the display of a document or enrich its content to facilitate au ...
for
speech synthesis
Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal langua ...
applications. It is a recommendation of the
W3C
The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working together in ...
's
Voice Browser {{Short description, Interactive voice user interface
A voice browser is a Application software, software application that presents an interactive voice user interface to the user in a manner analogous to the functioning of a web browser interpretin ...
Working Group. SSML is often embedded in
VoiceXML
VoiceXML (VXML) is a digital document standard for specifying interactive media and voice dialogs between humans and computers. It is used for developing audio and voice response applications, such as banking systems and automated customer service ...
scripts to drive interactive telephony systems. However, it also may be used alone, such as for creating audio books. For desktop applications, other markup languages are popular, including
Apple's embedded speech commands, and
Microsoft's SAPI Text to speech (TTS) markup, also an XML language. It is also used to produce sounds via Azure Cognitive Services' Text to Speech API or when writing third-party skills for
Google Assistant or
Amazon Alexa.
SSML is based on the
Java Speech Markup Language (JSML) developed by
Sun Microsystems
Sun Microsystems, Inc., often known as Sun for short, was an American technology company that existed from 1982 to 2010 which developed and sold computers, computer components, software, and information technology services. Sun contributed sig ...
, although the current recommendation was developed mostly by speech synthesis vendors. It covers virtually all aspects of synthesis, although some areas have been left unspecified, so each vendor accepts a different variant of the language. Also, in the absence of markup, the synthesizer is expected to do its own interpretation of the text.
Example
Here is an example of an SSML document:
Telephone Menu: Level 1
For English, press one.
Para español, oprima el dos.
Features
SSML specifies a fair amount of markup for
prosody, which is not included in the above example. This includes markup for
* pitch
* contour
* pitch range
* rate
* duration
* volume
See also
*
Pronunciation Lexicon Specification (PLS)
*
Speech Recognition Grammar Specification (SRGS)
*
Semantic Interpretation for Speech Recognition (SISR)
*
SABLE speech synthesis markup language, intended to combine SSML, STML, and JSML
References
External links
W3C SSML 1.1 Recommendation W3C SSML 1.0 Recommendation
{{Speech synthesis
Speech synthesis
XML-based standards
World Wide Web Consortium standards
Markup languages
2004 introductions