/**
 * SimpleVAD - Energy-based Voice Activity Detection
 *
 * This implementation uses audio energy analysis to detect speech without requiring
 * machine learning models. It's fast, requires no downloads, but less accurate than Silero VAD.
 *
 * Algorithm:
 * - Analyzes audio samples in real-time using Web Audio API
 * - Calculates RMS (Root Mean Square) energy level
 * - Detects speech when energy exceeds threshold
 * - Uses redemption frames to avoid flickering (brief silence during speech)
 */
/**
 * SimpleVAD configuration
 */
export interface SimpleVADConfig {
    /** MediaStream from microphone */
    stream: MediaStream;
    /** Energy threshold for speech detection (0-1, default: 0.15) */
    energyThreshold?: number;
    /** Sample rate in Hz (default: 16000) */
    sampleRate?: number;
    /** FFT size for frequency analysis (default: 2048) */
    fftSize?: number;
    /** Analysis interval in ms (default: 100) */
    analysisInterval?: number;
    /** Minimum duration of silence (in frames) before speech is considered ended (default: 8) */
    redemptionFrames?: number;
    /** Called when speech starts */
    onSpeechStart?: () => void;
    /** Called when speech ends */
    onSpeechEnd?: () => void;
}
/**
 * SimpleVAD class
 * Energy-based voice activity detection using Web Audio API
 */
export declare class SimpleVAD {
    private audioContext;
    private analyser;
    private microphone;
    private intervalId;
    private config;
    private stream;
    private isSpeaking;
    private silenceFrames;
    private isActive;
    constructor(config: SimpleVADConfig);
    /**
     * Start VAD processing
     */
    start(): Promise<void>;
    /**
     * Stop VAD processing
     */
    stop(): Promise<void>;
    /**
     * Pause VAD processing
     */
    pause(): void;
    /**
     * Resume VAD processing
     */
    resume(): void;
    /**
     * Check if currently speaking
     */
    isSpeakingNow(): boolean;
    /**
     * Start the audio analysis loop
     */
    private startAnalysis;
    /**
     * Analyze a single audio frame
     */
    private analyzeFrame;
    /**
     * Calculate RMS (Root Mean Square) energy from frequency data
     *
     * @param dataArray - Frequency data array
     * @returns RMS energy value
     */
    private calculateRMS;
}
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