SpeechRecognition.md

SpeechRecognition

Namespace: SpawnDev.BlazorJS.JSObjects
Inherits: EventTarget
Source: JSObjects/Speech/SpeechRecognition.cs

The SpeechRecognition interface of the Web Speech API is the controller interface for the recognition service; this also handles the SpeechRecognitionEvent sent from the recognition service.

Constructors

Signature	Description
SpeechRecognition(IJSInProcessObjectReference _ref)	Deserialization constructor
SpeechRecognition()	Creates a new SpeechRecognition.

Properties

Property	Type	Access	Description
Grammars	SpeechGrammarList	get	Returns and sets a collection of SpeechGrammar objects that represent the grammars that will be understood by the current SpeechRecognition.
Lang	string	get	Returns and sets the language of the current SpeechRecognition. If not specified, this defaults to the HTML lang attribute value, or the user agent's language setting if that isn't set either.
Continuous	bool	get	Returns and sets whether continuous results are returned for each recognition, or only a single result. Defaults to false (single result).
InterimResults	bool	get	Returns and sets whether interim results should be returned (true) or not (false). Interim results are results that are not yet final (e.g. the SpeechRecognitionResult.isFinal property is false).
MaxAlternatives	int	get	Returns and sets the maximum number of SpeechRecognitionAlternative objects provided per result. The default value is 1.

Methods

Method	Return Type	Description
Start()	void	Starts the speech recognition service listening to incoming audio with intent to recognize grammars associated with the current SpeechRecognition.
Stop()	void	Stops the speech recognition service from listening to incoming audio, and attempts to return a SpeechRecognitionResult using the audio captured so far.
Abort()	void	Stops the speech recognition service from listening to incoming audio, and doesn't attempt to return a SpeechRecognitionResult.

Events

Event	Type	Description
OnAudioEnd	ActionEvent<Event>	Fired when the speech recognition service has detached from a stream or some other reason.
OnAudioStart	ActionEvent<Event>	Fired when the user agent has started to capture audio.
OnEnd	ActionEvent<Event>	Fired when the speech recognition service has finished listening to incoming audio.
OnError	ActionEvent<SpeechRecognitionErrorEvent>	Fired when a speech recognition error occurs.
OnNoMatch	ActionEvent<SpeechRecognitionEvent>	Fired when the speech recognition service returns a final result with no significant recognition. This may involve some degree of recognition, which doesn't meet or exceed the confidence threshold.
OnResult	ActionEvent<SpeechRecognitionEvent>	Fired when the speech recognition service returns a result - a word or phrase has been positively recognized and this has been communicated back to the app.
OnSoundEnd	ActionEvent<Event>	Fired when the sound that is being recognized has stopped being detected.
OnSoundStart	ActionEvent<Event>	Fired when any sound - recognisable speech or not - has been detected.
OnSpeechEnd	ActionEvent<Event>	Fired when the speech recognition service has stopped being detected.
OnSpeechStart	ActionEvent<Event>	Fired when sound that is recognized by the speech recognition service as speech has been detected.
OnStart	ActionEvent<Event>	Fired when the speech recognition service has begun listening to incoming audio with intent to recognize grammars associated with the current SpeechRecognition.

Example

// Create a speech recognition instance
using var recognition = new SpeechRecognition();

// Configure recognition settings
recognition.Lang = "en-US";
recognition.Continuous = true;
recognition.InterimResults = true;
recognition.MaxAlternatives = 1;

// Subscribe to events using named methods (required for proper cleanup)
recognition.OnResult += Recognition_OnResult;
recognition.OnError += Recognition_OnError;
recognition.OnEnd += Recognition_OnEnd;
recognition.OnStart += Recognition_OnStart;

// Start listening (requires microphone permission)
recognition.Start();

// Stop listening and get final result
// recognition.Stop();

// Or abort without returning results
// recognition.Abort();

// Clean up event handlers before disposal
recognition.OnResult -= Recognition_OnResult;
recognition.OnError -= Recognition_OnError;
recognition.OnEnd -= Recognition_OnEnd;
recognition.OnStart -= Recognition_OnStart;

void Recognition_OnResult(SpeechRecognitionEvent e)
{
    using var results = e.Results;
    var index = e.ResultIndex;
    using var result = results[index];
    using var alternative = result[0];
    Console.WriteLine($"Recognized: {alternative.Transcript} (confidence: {alternative.Confidence})");
}

void Recognition_OnError(SpeechRecognitionErrorEvent e)
{
    Console.WriteLine($"Speech recognition error: {e.Error}");
}

void Recognition_OnEnd(Event e)
{
    Console.WriteLine("Speech recognition ended");
    // Restart if continuous listening is desired
}

void Recognition_OnStart(Event e)
{
    Console.WriteLine("Listening for speech...");
}