Syncfusion Angular SpeechToText Component

Component Overview

The Syncfusion Angular SpeechToText component is a lightweight, accessible control that converts spoken words into text using the browser's native Speech Recognition API.

Key Capabilities:

• Real-time Transcription - Convert speech to text with interim and final results
• Button Customization - Configure icon, text, positioning, and styling for start/stop buttons
• Tooltip Support - Add tooltips with custom content and positioning for better UX
• Events & Interactions - Handle listening state changes, errors, and transcript updates
• Methods - Programmatic control via startListening() and stopListening() methods
• Language Support - Multi-language recognition with locale configuration
• Globalization - RTL support and localization for international applications
• Styling Options - CSS classes, HTML attributes, and theme integration
• Security Features - HTTPS enforcement and explicit microphone permissions
• Browser Compatibility - Chrome 25+, Edge 79+, Safari 12+, Opera 30+

Documentation and Navigation Guide

Getting Started

📄 Read: references/getting-started.md

• Package installation (Ivy vs ngcc compatibility)
• Angular project setup and configuration
• CSS imports and theme management
• Module imports and basic component rendering
• Button content customization
• Complete working example with TextArea integration

Button Customization

📄 Read: references/button-customization.md

• ButtonSettingsModel configuration
• Start and stop button content labels
• Icon customization with CSS classes
• Icon positioning (top, bottom, left, right)
• Primary button styling for emphasis
• Visual style variations and best practices

Tooltip Configuration

📄 Read: references/tooltip-configuration.md

• TooltipSettingsModel setup
• Tooltip content for start and stop states
• Tooltip positioning relative to button
• Enabling and disabling tooltips
• Practical tooltip usage patterns

Styling and Appearance

📄 Read: references/styling-and-appearance.md

• CSS class system (e-primary, e-outline, e-info, e-success, e-warning, e-danger)
• Custom styling with cssClass property
• Theme configuration and integration
• HTML attributes customization
• Custom CSS examples and advanced styling

Events and Methods

📄 Read: references/events-and-methods.md

• Event types (created, onStart, onStop, onError, transcriptChanged)
• Event handler implementation and event arguments (including event, name properties)
• Programmatic control with startListening(), stopListening(), and destroy() methods
• Controlling component state with listeningState property (Inactive, Listening, Stopped)
• Canceling listening with the cancel property in onStart event
• Distinguishing user vs programmatic actions with isInteracted property
• Event handling patterns for different scenarios
• Managing listening lifecycle programmatically
• State transition management and workflow control
• Component cleanup and memory management

Speech Recognition Features

📄 Read: references/speech-recognition-features.md

• Retrieving transcript from speech input
• Setting recognition language (lang property)
• Interim results configuration (allowInterimResults)
• Listening state management (Inactive, Listening, Stopped)
• Tooltip visibility control (showTooltip)
• Disabled state configuration
• State persistence with enablePersistence property
• State monitoring and status management
• Custom state management with localStorage

Internationalization

📄 Read: references/internationalization.md

• Localization setup using L10n.load()
• Translation key mapping for error messages and labels
• Multi-language implementation examples
• RTL (Right-to-Left) support enablement
• Language-specific configuration best practices

Security and Error Handling

📄 Read: references/security-and-error-handling.md

• Security risks and mitigation strategies
• Data transmission and privacy concerns
• HTTPS enforcement and MITM prevention
• Microphone permission management
• Error type handling (no-speech, aborted, audio-capture, not-allowed, service-not-allowed, network, unsupported-browser, default)
• Browser support matrix and compatibility

Quick Start Example

Here's a minimal working SpeechToText component with transcript output:

import { Component, ViewChild } from '@angular/core';
import { SpeechToTextModule, TextAreaComponent, TextAreaModule, TranscriptChangedEventArgs } from '@syncfusion/ej2-angular-inputs';

@Component({
    imports: [SpeechToTextModule, TextAreaModule],
    standalone: true,
    selector: 'app-root',
    template: `
    <div class="speechText-container">
        <button ejs-speechtotext 
                (transcriptChanged)="onTranscriptChange($event)">
        </button>
        <ejs-textarea #outputTextarea 
                      id="textareaInst" 
                      value="" 
                      rows="5" 
                      cols="50" 
                      resizeMode="None" 
                      placeholder="Transcribed text will be shown here...">
        </ejs-textarea>
    </div>`
})
export class AppComponent {
    @ViewChild('outputTextarea') outputTextarea!: TextAreaComponent;
    
    onTranscriptChange(args: TranscriptChangedEventArgs): void {
        this.outputTextarea.value = args.transcript;
    }
}

Common Patterns

Pattern 1: Customized Button with Events

Implement a styled button with custom labels and event handlers:

public buttonSettings: ButtonSettingsModel = {
    content: 'Start Listening',
    stopContent: 'Stop Listening',
    iconCss: 'e-icons e-play',
    stopIconCss: 'e-icons e-pause',
    isPrimary: true
};

onListeningStart(args: StartListeningEventArgs): void {
    console.log('Listening started');
}

onListeningStop(args: StopListeningEventArgs): void {
    console.log('Listening stopped');
}

Pattern 2: Multi-Language Support

Configure localization for international applications:

L10n.load({
    'de': {
        "speech-to-text": {
            "startAriaLabel": "Drücken Sie, um zu sprechen",
            "stopAriaLabel": "Drücken Sie, um zu stoppen",
            "noSpeechError": "Keine Sprache erkannt"
        }
    }
});

Pattern 3: Programmatic Control

Manage listening state programmatically without user button clicks:

@ViewChild('speechtotext') speechToText!: SpeechToTextComponent;

public startListening(): void {
    this.speechToText.startListening();
}

public stopListening(): void {
    this.speechToText.stopListening();
}

Pattern 4: Error Handling

Handle speech recognition errors gracefully:

onErrorHandler(args: ErrorEventArgs): void {
    if (args.error === 'no-speech') {
        console.log('No speech detected. Please try again.');
    } else if (args.error === 'not-allowed') {
        console.log('Microphone permission denied.');
    }
}

Pattern 5: Conditional Listening with Cancel

Control when listening can start using the cancel property:

onListeningStart(args: StartListeningEventArgs): void {
    // Cancel listening if conditions aren't met
    if (!this.hasPermission || !navigator.onLine) {
        args.cancel = true;
        alert('Cannot start listening. Check permissions and connection.');
        return;
    }
    
    // Track if user or system triggered the action
    if (args.isInteracted) {
        console.log('User clicked the button');
    } else {
        console.log('Started programmatically');
    }
}

Pattern 6: Distinguishing Interim vs Final Results

Handle interim and final transcripts differently:

onTranscriptChange(args: TranscriptChangedEventArgs): void {
    if (args.isInterimResult) {
        // Show interim results in real-time (lighter styling)
        this.interimText = args.transcript;
    } else {
        // Process final results (save, send to API, etc.)
        this.finalText = args.transcript;
        this.saveTranscript(args.transcript);
    }
}

Pattern 7: Controlling Component State

Programmatically control the component's operational state:

import { SpeechToTextState } from '@syncfusion/ej2-angular-inputs';

export class AppComponent {
    public currentState: SpeechToTextState = SpeechToTextState.Inactive;
    
    // Set component to listening state
    startListening(): void {
        this.currentState = SpeechToTextState.Listening;
    }
    
    // Set component to stopped state
    stopListening(): void {
        this.currentState = SpeechToTextState.Stopped;
    }
    
    // Reset to inactive state
    resetState(): void {
        this.currentState = SpeechToTextState.Inactive;
    }
}

Pattern 8: Proper Component Cleanup

Ensure proper cleanup to prevent memory leaks:

import { OnDestroy } from '@angular/core';

export class AppComponent implements OnDestroy {
    @ViewChild('speechtotext') speechToText!: SpeechToTextComponent;
    
    ngOnDestroy(): void {
        if (this.speechToText) {
            this.speechToText.stopListening();
            this.speechToText.destroy();
        }
    }
}

Key Props

Prop	Type	Default	Purpose
buttonSettings	ButtonSettingsModel	-	Configure button appearance and labels
tooltipSettings	TooltipSettingsModel	-	Customize tooltip content and position
lang	string	'en-US'	Set speech recognition language
allowInterimResults	boolean	true	Enable real-time interim transcription
transcript	string	''	Current recognized text (read-only)
listeningState	SpeechToTextState	Inactive	Monitor listening status (Inactive, Listening, Stopped)
showTooltip	boolean	true	Display tooltip on hover
disabled	boolean	false	Disable component interaction
enablePersistence	boolean	false	Persist component state across page reloads
enableRtl	boolean	false	Enable right-to-left text direction
cssClass	string	-	Apply custom CSS classes
htmlAttributes	object	-	Set custom HTML attributes on button
locale	string	'en-US'	Set UI localization language

Browser Requirements

The SpeechToText component requires:

• Active internet connection for speech recognition processing
• Browser Speech Recognition API support:
  • Chrome 25+
  • Edge 79+
  • Safari 12+
  • Opera 30+
  • Firefox: Not Supported
• Microphone hardware connected to the system
• User microphone permission granted in browser settings
• HTTPS context for secure microphone access (recommended)