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ai.languages

Use ai.languages to configure the spoken language of your AI Agent, as well as the TTS engine, voice, and fillers.

ai.languages
object[]

An array of objects that accepts the languages parameters.

Parameters​

languages[].name
stringrequired
Default: `English`

Name of the language ("French", "English", etc). This value is used in the system prompt to instruct the LLM what language is being spoken.

languages[].code
stringrequired
Default: `en-US`

Set the language code for ASR

(STT) purposes. By default, SignalWire uses Deepgram's Nova-3 STT engine, so this value should match a code from Deepgram's Nova-3 language codes table.

Note: If a different STT model was selected using the openai_asr_engine parameter, you must select a code supported by that engine.

languages[].voice
stringrequired
Default: Standard-tier voice picked by SignalWire

String format: <engine id>.<voice id>.
Select engine from gcloud, polly, elevenlabs, or deepgram. Select voice from TTS provider reference.
For example, "gcloud.fr-FR-Neural2-B".

See voice usage for more details.

languages[].emotion
string
Default: None

Enables emotion for the set TTS engine. This allows the AI to express emotions when speaking. A global emotion or specific emotions for certain topics can be set within the prompt of the AI.
Valid values: auto
IMPORTANT: Only works with Cartesia TTS engine.

languages[].function_fillers
string[]
Default: None

An array of strings to be used as fillers in the conversation when the agent is calling a SWAIG function. The filler is played asynchronously during the function call.

languages[].model
string
Default: None

The model to use for the specified TTS engine (e.g. arcana). Check the TTS provider reference for the available models.

languages[].speech_fillers
string[]
Default: None

An array of strings to be used as fillers in the conversation. This helps the AI break silence between responses.

Note: speech_fillers are used between every 'turn' taken by the LLM, including at the beginning of the call. For more targed fillers, consider using function_fillers.

languages[].speed
string
Default: None

The speed to use for the specified TTS engine. This allows the AI to speak at a different speed at different points in the conversation. The speed behavior can be defined in the prompt of the AI.
Valid values:* auto
IMPORTANT: Only works with Cartesia TTS engine.

languages[].params
object
Default: None

TTS engine-specific parameters for this language. Accepts the params parameters.

languages[].fillers
string[]deprecated
Default: None
An array of strings to be used as fillers in the conversation and when the agent is calling a SWAIG function.Deprecated: Use speech_fillers and function_fillers instead.
languages[].engine
stringdeprecated
Default: `gcloud`
The engine to use for the language. For example, "elevenlabs".Deprecated. Set the engine with the voice parameter.

Language params​

Use languages[].params to configure TTS engine-specific parameters for individual languages. These settings override global ai.params values for this specific language.

languages[].params.similarity
number
Default: 0.75

The similarity slider dictates how closely the AI should adhere to the original voice when attempting to replicate it. The higher the similarity, the closer the AI will sound to the original voice. Valid values range from 0.0 to 1.0.

Important: Only works with ElevenLabs TTS engine.

languages[].params.stability
number
Default: 0.50

The stability slider determines how stable the voice is and the randomness between each generation. Lowering this slider introduces a broader emotional range for the voice. Valid values range from 0.0 to 1.0.

Important: Only works with ElevenLabs TTS engine.

Use voice strings​

Compose the voice string using the <engine id>.<voice id> syntax.

First, select your engine using the gcloud, polly, elevenlabs, or deepgram identifier. Append a period (.), and then the specific voice ID (for example, en-US-Casual-K) from the TTS provider. Refer to SignalWire's Supported Voices and Languages for guides on configuring voice IDs strings for each provider.

Supported voices and languages​

SignalWire's cloud platform integrates with leading text-to-speech providers. For a comprehensive list of supported engines, languages, and voices, refer to our documentation on Supported Voices and Languages.

Examples​

Set a single language​

SWML will automatically assign the language (and other required parameters) to the defaults in the above table if left unset. This example uses ai.language to configure a specific English-speaking voice from ElevenLabs.

languages:
  - name: English
    code: en-US
    voice: elevenlabs.rachel
    speech_fillers:
      - one moment please,
      - hmm...
      - let's see,

Set multiple languages​

SWML will automatically assign the language (and other required parameters) to the defaults in the above table if left unset. This example uses ai.language to configure multiple languages using different TTS engines.

languages:
  - name: Mandarin
    code: cmn-TW
    voice: gcloud.cmn-TW-Standard-A
  - name: English
    code: en-US
    voice: elevenlabs.rachel

Configure global ElevenLabs parameters​

Configure stability and similarity globally for all ElevenLabs voices using ai.params:

ai:
  params:
    eleven_labs_stability: 0.6
    eleven_labs_similarity: 0.8
  languages:
    - name: English
      code: en-US
      voice: elevenlabs.josh

Configure per-language ElevenLabs parameters​

Configure different stability and similarity values for each language using languages[].params:

ai:
  languages:
    - name: English
      code: en-US
      voice: elevenlabs.josh
      params:
        stability: 0.6
        similarity: 0.8
    - name: Spanish
      code: es-ES
      voice: elevenlabs.maria
      params:
        stability: 0.4
        similarity: 0.9

Mixed configuration​

Per-language params override global params:

ai:
  params:
    eleven_labs_stability: 0.5
    eleven_labs_similarity: 0.75
  languages:
    - name: English
      code: en-US
      voice: elevenlabs.josh
      # Uses global defaults: stability=0.5, similarity=0.75
    - name: Spanish
      code: es-ES
      voice: elevenlabs.maria
      params:
        stability: 0.3
        # Overrides only stability, similarity still uses global 0.75