Docs/Voice

Voice

Stream captured audio to an NPC and play back its spoken reply.

Voice runs over the same connection as text. The SDK gives you the wire methods — streaming audio chunks in, receiving synthesized speech back — but capturing the player's microphone and deciding when they've stopped talking is up to you, using the browser's own audio APIs.

No built-in microphone capture or voice detection
Unlike the Unity SDK's VoiceNPC component, the Web SDK does not capture your microphone or run voice-activity detection for you — the browser sandbox makes that a much more involved, permission-gated integration than in a compiled game engine. This is a real gap today, not a hidden limitation: you own capture (e.g. the MediaRecorder API or an AudioWorklet) and pass the SDK raw PCM bytes.

Sending audio

Stream chunks as you capture them, then send one final chunk with end: true — or let the server auto-finalize once it has buffered about 5MB, whichever comes first:

voice.ts
// pcmChunk: ArrayBuffer | Uint8Array of raw audio you've already captured
connection.sendVoiceChunk(pcmChunk, false);

// ...more chunks as they're captured...

connection.sendVoiceChunk(finalChunk, true); // end: true
data
Raw PCM bytes for this chunk, as an ArrayBuffer or Uint8Array. The SDK base64-encodes it for the wire.
end
Set true on the final chunk of the utterance.
senderId
Optional. Overrides the connection's default player id for this utterance.

Once the server finishes transcribing, a transcript event fires with what it heard, followed by the normal chat events — voice replies arrive as one complete chatChunk rather than streamed token by token, since grounding runs before anything is sent back.

Playing the reply

Synthesized speech arrives as raw binary WebSocket frames — no JSON envelope, one frame per sentence, in playback order:

voice.ts
connection.on("audio", (bytes) => {
  // bytes: ArrayBuffer of raw synthesized speech for one sentence.
  // Decode/queue it with the Web Audio API in your own playback pipeline.
  playAudioChunk(bytes);
});
Microphone permission
Requesting microphone access requires a user gesture in most browsers and shows a permission prompt the player can deny. Request access before the first voice interaction, and offer a text fallback — text and voice can be used freely in the same connection, including in the same conversation.