Neuphonic

Neuphonic generates low-latency speech in more than forty languages, including English, most European languages, Arabic, Hindi, Japanese, Korean and Mandarin Chinese. Neuphonic tuning is passed in synthesizer.options.

{
  "verb": "say",
  "text": "Hi there, your order ships today.",
  "synthesizer": {
    "vendor": "neuphonic",
    "language": "en-US",
    "voice": "eeb488b8-d532-4235-aa57-f070cfc44750",
    "options": {
      "speed": 1.0
    }
  }
}

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 Neuphonic dashboard. jambonz sends the key in the X-API-KEY header. Add it as a Neuphonic speech credential in the portal or API. Neuphonic is used for text-to-speech only.

Models

Neuphonic has no model setting: the voice selects the model.

Voices and languages

A voice is a Neuphonic voice id (a UUID). The portal lists Neuphonic’s stock voices by language; Hannah (eeb488b8-d532-4235-aa57-f070cfc44750) is the English default. Voices you have cloned or created in your Neuphonic account are not listed, but work when you enter their id as a custom voice. If no voice is given, Neuphonic picks its own default voice.

synthesizer.language is sent as Neuphonic’s language code: the language prefix is used, so en-US is sent as en and de-DE as de. A few are mapped: ar-SA is sent as ar_sa, ar-MA as ar_maghrebi, nb-* and nn-* as no, and cmn-* as zh. A value that already contains an underscore is sent as written. Set options.language to send a Neuphonic language code directly; it takes precedence over synthesizer.language. If neither is set, en is used.

Options

language

string

Neuphonic language code, sent as written, such as en, es or ar_sa. Overrides the code derived from synthesizer.language.

speed

number

Speaking rate. Neuphonic’s effective values are 0.7, 1.0 and 1.5; its default is 1.0.

temperature

number

Sampling temperature, 0 – 1.

ipa_key

string

Regional sounds for <phoneme:...> tags: es-castilian or pt-br.

timestamps

boolean

Return word-level timestamps. Streaming only. When unset, jambonz turns them on if alignment is enabled.

Every option is optional. An option you don’t set is not sent, so Neuphonic’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.neuphonic.com.

Streaming

Neuphonic 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 Neuphonic over a live connection and opens a fresh connection for each turn; on barge-in it closes the connection and reconnects.

Neuphonic returns word-level timestamps, so alignment events are available when alignment is enabled.