Voice Activity Detection (VAD) Demo

This example demonstrates Voice Activity Detection using PromptKit’s audio package.

Features

• SimpleVAD: Basic voice activity detection using RMS energy analysis
• State Tracking: Monitor transitions between quiet/starting/speaking/stopping
• Configurable Parameters: Tune sensitivity for different environments
• Event Notifications: React to state changes in real-time

Running

cd sdk/examples/vad-demo
go run .

This example runs with simulated audio data - no microphone required.

VAD States

State	Description
quiet	No voice activity detected
starting	Voice beginning (within start threshold)
speaking	Active speech detected
stopping	Voice ending (within stop threshold)

Configuration

Default Parameters

params := audio.DefaultVADParams()
// Confidence: 0.5
// StartSecs: 0.2
// StopSecs: 0.8
// MinVolume: 0.01
// SampleRate: 16000

Strict VAD (noisy environments)

params := audio.VADParams{
    Confidence: 0.7,   // Higher confidence required
    StartSecs:  0.3,   // Longer speech to trigger
    StopSecs:   1.2,   // Allow longer pauses
    MinVolume:  0.02,  // Higher volume threshold
    SampleRate: 16000,
}

Sensitive VAD (quiet environments)

params := audio.VADParams{
    Confidence: 0.3,   // More sensitive
    StartSecs:  0.1,   // Quick start detection
    StopSecs:   0.5,   // Quick end detection
    MinVolume:  0.005, // Detect quiet speech
    SampleRate: 16000,
}

State Change Events

vad, _ := audio.NewSimpleVAD(audio.DefaultVADParams())
stateChanges := vad.OnStateChange()

go func() {
    for event := range stateChanges {
        fmt.Printf("State: %s -> %s (confidence: %.2f)\n",
            event.PrevState, event.State, event.Confidence)
    }
}()

Integration with SDK

VAD is typically used with audio sessions:

conv, _ := sdk.Open("./pack.json", "assistant")

// Create audio session with VAD
session, _ := conv.OpenAudioSession(ctx,
    sdk.WithSessionVAD(audio.NewSimpleVAD(audio.DefaultVADParams())),
)

// VAD automatically processes audio chunks
session.SendChunk(ctx, audioChunk)

Notes

• VAD is energy-based (RMS volume analysis)
• Works with 16-bit PCM audio at configurable sample rates
• Default sample rate is 16kHz (common for speech recognition)
• Transition thresholds prevent false positives from brief sounds