TTS caching

Speech synthesis is often the most expensive step in a voice agent. Greetings, confirmations, and hold messages repeat on every call. TTS caching stores the audio for a phrase the first time it is synthesized, then reuses it on later calls. By policy, the cache is isolated per organization and PII-aware, so your audio is not stored where another customer can reach it. Cached audio expires on a sliding schedule: phrases that keep coming up stay cached, and unused ones age out.

Skip the cache

TTS caching is on by default for every use case. It runs the same way whether the audio comes from an SLNG-hosted model or BYOK. To skip the cache for a connection, send the X-Slng-Cache-Bypass header set to true. The gateway then neither reads nor writes cached audio for that connection. Leave the header out, or set it to false, to keep caching on.

Skip the cache

import WebSocket from "ws";

const ws = new WebSocket(
  "wss://api.slng.ai/v1/tts/slng/deepgram/aura:2-en",
  {
    headers: {
      Authorization: `Bearer ${process.env.SLNG_API_KEY}`,
      "X-Slng-Cache-Bypass": "true",
    },
  }
);

ws.on("open", () => {
  ws.send(JSON.stringify({ type: "text", text: "Hello from sunny Barcelona!" }));
});

ws.on("message", (data) => {
  playAudio(data); // play each chunk as it arrives
});

// Call ws.close() when the turn or session ends so the server releases resources.

SLNG models and your own keys

Caching works the same whether the agent uses an SLNG-hosted model or a model on your own provider key. There is nothing extra to set up for either.

Regions

TTS caching is region-aware and organization-scoped: your speech is never synthesized or hosted in another region.

Get started

Regions

Execution layer

Agent Builder

Models

Integrate

Skip the cache

SLNG models and your own keys

Regions

​Skip the cache

​SLNG models and your own keys

​Regions

Skip the cache

SLNG models and your own keys

Regions