Java Speech Development Kit: A Tutorial
As mentioned, the result objects are created as answers to the recognition performed by the SDK Java. They are responsible for generating recognition result events or ResultEvents that might be intercepted by ResultListeners. These events are implemented in such a way that it is possible for the application to have access to the object that generated it (following the Java standard) through the getSource method. (The getSource method belongs to the java.util.EventObject class interface of which ResultEvent inherits.) In this context we will have a result object, or a descendent, returned.
The possible result object states are:
ACCEPTED: the audio item was understood and an association with one of the active grammars was determined.
REJECTED: the audio item was understood, but the recognizer considers a high possibility of a mistake having been made. That means, the recognizer was able to understand (to associate a string, or token, meaning the heard sound) what was said, but there was not enough information to be sure of the recognition, due to poor sound quality, a bad pronunciation or even due to hardware problems. These results must be treated carefully by the application.
UNFINALIZED: the audio item was understood and it is been processed, but it was not possible yet to determine an association with one of the active grammars.
Accept or Reject: rejection of a result indicates that the recognizer is not confident that it has accurately recognized what a user said. Rejection can be controlled through the RecognizerProperties interface with the setConfidenceLevel method. Increasing the confidence level requires the recognizer to have greater confidence to accept a result, so more results are likely to be rejected.
Below is an illustration of the recognition cycle and some of the fired events:
By looking at the figure, we can establish the relationship between the result object states and the events (ResultEvent) that the listeners (ResultListeners) are able to intercept.
A RESULT_CREATED event creates a result object. A new result is started in the UNFINALIZED state.
UNFINALIZED state: RESULT_UPDATED events indicate a change in finalized and/or unfinalized tokens; a GRAMMAR_FINALIZED event indicates that the grammar matched by this result has been identified.
The RESULT_ACCEPTED event finalizes a result by indicating a change in state from UNFINALIZED to ACCEPTED.
The RESULT_REJECTED event finalizes a result by indicating a change in state from UNFINALIZED to REJECTED.
In the finalized states (ACCEPTED and REJECTED), the AUDIO_RELEASED and TRAINING_INFO_RELEASED events also may be issued.
The result objects are:
Result: the most primitive form of a created result. This form is used until the recognition cycle is finished, before all the information relating to a certain audio entrance is available. The substates might be FINALIZED or UNFINALIZED.
FinalResult: created when we have all the information relating to a certain audio entrance, that is, it is a complete result able to supply all the possible data as a consequence of a complete recognition. Its substates are ACCEPTED or REJECTED (always FINALIZED).
The information available in a result is determined by the type of grammar to which it was associated. Therefore, completing the model, the FinalResult interface is inherited by two other interfaces exclusively implemented by the recognizer for a certain finalized result, they are:
FinalRuleResult: the final result in consequence of an audio entrance associated to a RuleGrammar, with the substates ACCEPTED or REJECTED (FINALIZED).
FinalDictationResult: the final result in consequence of an audio entrance associated to a DictationGrammar, with the substates ACCEPTED or REJECTED (FINALIZED).
This schema is useful on the following situations:
Makes it possible to have access to the created results before they are finalized, for that we use simple result objects.
We can have both types of grammars associated to the same recognizer. And, in certain moments, we might need information that is not relevant either to an association with a rule or to a dictation grammar, but simply for a finalized result. For that we can use the FinalResult interface without having to test the nature of the result.
Having two types of finalized results, we can have additional data referring to the type of the grammar associated, increasing the control of applications.