Java Speech Development Kit: A Tutorial

Java Speech Markup Language (JSML) is a markup language derived from XML and is used to describe an audio entrance in the synthesizers of the API. Its elements are able to supply detailed information about how to pronounce the text provided to the synthesizer. These elements describe the structure of a document (paragraphs, phrases), the words pronounced, text markers and prosodic elements that control phrasing, emphasis, pitch, speaking rate and other important characteristics. Appropriate markup of text improves the quality and naturalness of the synthesized voice.

JSML is used as arguments to the synthesizers and can be accessed through one of the forms of the method speak. It might be provided in a text file with the JSML formatted text or in small phrases as arguments for the method. Table 4 shows the JSML tags:

Table 2. JSML Tags

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The recognizers are the entities responsible for speech recognition. They are created through the Central class and are initialized using the allocate method. They process the audio entering in parallel to the main application.

The recognition is done with the help of a set of words that limit the universe of possibilities that can be pronounced by the user. These sets are extensible, and new words can be added, increasing the application functionality. The sets are known as grammars, and it is necessary to have at least one grammar associated with each recognizer.

When audio enters the recognizers, they try to determine an association between the spoken words and their associated grammars. The recognition process culminates on the creation of objects named results. Results have types ACCEPTED or REJECTED accordingly to the confidence level determined by the setConfidenceLevel method (the default value is 0.5).

In the same way as the synthesizers, the recognizers are created through the Central class in two possible ways:

1. Accessing the recognizer's default implementation that better fits the current locale. It is the simplest manner and the most common:

                 Locale.setDefault("en","US");
                 Recognizer recognizer =
                 Central.createRocognizer(null);

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2. Accessing a recognizer that satisfies predetermined conditions, this method is used in cases where there are more than one recognizer implementation available. The required parameters are:

Any of the parameters might be null, and the Central class will try to make the best choice for them. These parameters are defined via a RecognizerModeDesc object, as shown here:

 RecognizerModeDesc(String engine, String mode, Locale locale, Boolean running,
 Boolean dictationGrammarSupported, SpeakerProfile[] profiles)

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