Async

Async generates speech with its Flash and Pro models in up to fifteen languages, including English, Spanish, French, German, Italian, Portuguese, Arabic, Russian, Japanese, Hindi and Mandarin Chinese. Async tuning is passed in synthesizer.options.

{
  "verb": "say",
  "text": "Hi there, your order ships today.",
  "synthesizer": {
    "vendor": "asyncai",
    "language": "en-US",
    "voice": "e0f39dc4-f691-4e78-bba5-5c636692cc04",
    "options": {
      "model_id": "async_flash_v1.0",
      "speed_control": 1.1
    }
  }
}

You can also set these in the portal under Extra Options on the speech credential, in which case they apply to every request that uses that credential. Settings supplied on the verb take precedence.

Credential

Create an API key in the Async dashboard. Keys start with sk_, and jambonz sends the key in the x-api-key header (as the api_key query parameter when streaming). Add it as an Async speech credential in the portal or API, using the vendor id asyncai. Async is used for text-to-speech only.

Models

Pick the model on the speech credential, or set options.model_id. jambonz always asks Async for 16-bit PCM at the call’s sample rate.

Voices and languages

A voice is an Async voice id, a UUID. The portal lists e0f39dc4-f691-4e78-bba5-5c636692cc04, Async’s default voice, for every language. Other voices from your Async account work when you enter their id as a custom voice.

synthesizer.language is sent as its language prefix, so en-US is sent as en and pt-BR as pt; cmn-* is sent as zh and iw-* as he. Async supports en, fr, es, de, it, pt, ar, ru, ro, ja, he, hy, tr, hi and zh. Any other language is not sent, and Async detects the language from the text. Set options.language to send a language code directly; it takes precedence over synthesizer.language. A language outside the chosen model may be rejected by Async.

Options

Every option is optional. An option you don’t set is not sent, so Async’s own default applies.

Endpoint override

To point at a non-default endpoint, such as a proxy, set the API base URL on the credential, or api_uri in its Extra Options. Leave it out to use api.async.com.

Streaming

Async supports TTS streaming, so it can be driven token by token from an LLM using tts:tokens, for example from the agent verb. jambonz streams text to Async over a live connection and starts a new Async context for each turn; on barge-in it closes the current context and drops its remaining audio instead of reconnecting.

Async does not return word-level timestamps, so alignment events are not available.