> ## Documentation Index
> Fetch the complete documentation index at: https://docs.larynth.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Voices

> Choose the voice and voice model your agent speaks with.

You choose your agent's voice. Larynth lists the voices and models that work on live calls, and you pick the one that fits your business.

## Browse the catalog

`GET /v1/catalog/voices` lists enabled voices. Filter by `language` or `model_id`. Each voice has a name, a description, the languages it speaks well (the first is its main language), tags, and a `preview_url` where a sample is available.

`GET /v1/catalog/models` lists enabled models. Filter by `kind`: `stt`, `llm`, `tts`, `s2s` or `embedding`. Each model shows `typical_reply_ms`, the typical time it adds to a reply, measured on our own infrastructure. Compare it before you choose, because a slower voice model makes your agent slower to answer.

The agent editor in the dashboard lists the same voices.

## Pick a voice

**1. Choose the model**

In cascade mode, set `tts_model_id` to the voice model. The default voice model is Cartesia Sonic 3.6. It is marked `is_default` in the catalog. You can choose any other enabled model.

**2. Choose the voice**

Set `tts_voice_id` to a voice from the catalog that belongs to that model. Match the voice to the agent's `language`. A draft warns you when they don't match.

**3. Listen, then test**

Play the preview, then make a [test call](https://docs.larynth.com/guides/test-in-browser.md). A voice can sound different over a phone line than in a preview.

**4. Publish**

The voice is part of the version. Publish to make it live. See [Build and publish an agent](https://docs.larynth.com/guides/build-and-publish-an-agent.md).

## Cost

Calls cost the same per minute for every voice by default. A voice or model can have a premium. `premium_micro_per_min` in the catalog is added to the call-minute rate, and it equals what billing charges. It is 0 when there is no premium. Amounts are in micro-USD: 1,000,000 equals \$1. See [Billing](https://docs.larynth.com/concepts/billing.md).

## Languages

Agents speak English for now. `GET /v1/catalog/languages` lists the call languages that are available, so check it rather than assuming. Your voice must speak the language you pick.

## Speech to speech

In S2S mode one model listens and speaks, so you choose a speech model instead of a separate voice. See [Agents](https://docs.larynth.com/concepts/agents.md#modes).

## Changes to the catalog

The catalog changes as voice models are added or retired. A voice or model with the status `deprecated` is on its way out. Check the catalog when you build a new agent.


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