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FeaturesTTS Vendor Settings

Speechmatics

British and American English preview voices on the same key as Speechmatics speech-to-text.

Speechmatics text-to-speech uses the same API key as Speechmatics speech-to-text. jambonz sends the text to Speechmatics’ POST /generate/<voice> endpoint and asks for 16 kHz PCM audio. Speechmatics tuning is passed in synthesizer.options.

{
  "verb": "say",
  "text": "Hi there, your order ships today.",
  "synthesizer": {
    "vendor": "speechmatics",
    "language": "en-GB",
    "voice": "sarah"
  }
}

You can also set options 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.

Speechmatics text-to-speech is a preview product. Its host, voices and limits may change; confirm availability with Speechmatics before production use.

Credential

Create an API key in the Speechmatics portal. jambonz sends it as a Bearer token. In the portal, open or add the Speechmatics speech credential and check Use for text-to-speech; one credential can serve both text-to-speech and speech-to-text.

FieldRequiredMeaning
API key (api_key)YesYour Speechmatics key, used for both TTS and STT.
Endpoint (speechmatics_stt_uri)Only for speech-to-textThe realtime STT host. A credential used only for text-to-speech can leave it out.
TTS host (api_uri)NoHost override for text-to-speech, such as a proxy. Set it over the API or as api_uri in Extra Options. Leave it out to use preview.tts.speechmatics.com.

When you save the credential, jambonz checks text-to-speech by synthesizing a short phrase with the sarah voice.

Voices and languages

LanguageVoices
English (UK) en-GBsarah (default, female), theo (male)
English (US) en-USmegan (female), jack (male)

Speechmatics has no language or model setting for text-to-speech; the voice decides how the text is spoken. jambonz uses synthesizer.language only to group voices in the portal and does not send it, so any language code works with any voice.

Options

Every option is optional. An option you don’t set is not sent.

sm_app
string

Sent as the sm-app query parameter, which Speechmatics uses to identify the calling application.

api_uri
string

Text-to-speech host override. http:// is used when given, otherwise https://. Overrides the credential’s TTS host.

{
  "sm_app": "my-voice-app"
}

Streaming

Speechmatics has no token-streaming websocket, so it does not support TTS streaming: use it for one-shot say, not for say with stream: true or the agent verb.