# May 4, 2026

## Aura-2 Voice Controls — Speed and Pronunciation

Aura-2 TTS voices now support runtime speed and pronunciation controls in English and Spanish, available on both batch and streaming WebSocket endpoints. Together, these controls give developers finer-grained tools to improve naturalness — tuning pacing and correcting pronunciation to match their needs.

Speed control adjusts the speaking rate of generated audio while maintaining natural prosody, with a supported range of 0.7x–1.5x. For Spanish voices, the recommended range is 0.9x–1.5x; values below 0.9x may introduce disfluencies.

Pronunciation control overrides the default pronunciation of specific words using inline IPA notation, e.g. `The patient was prescribed \{"word": "dupilumab", "pronounce": "duːˈpɪljuːmæb"\}.`

See [Voice Controls](/guides/tts-voice-controls-tts-voice-controls) for details.

### Voice Agent

These controls are also supported when using Aura-2 inside the Voice Agent API: set `speed` once at the session level, and have the LLM emit pronunciation overrides inline. See [Voice Agent TTS Controls](/guides/self-hosted-deployments-3-voice-agent-tts-controls) for the recommended setup.

### Self-Hosted

These controls are powered by an updated Aura-2 voice-pack model. Self-hosted deployments using a voice-pack from before [the April 2026 release](/guides/more-changelog-2026-4-30) will return `400 Bad Request` on requests including `speed` or `pronounce` parameters. See the [April 2026 self-hosted release notes](/guides/more-changelog-2026-4-30) for voice-pack version requirements and upgrade instructions.

## Related pages

- [Amazon SageMaker](./amazon-sagemaker-index.md)
- [Aura](./aura-index.md)
- [Changelog](../changelog.md)
- [Custom Vocabulary](./custom-vocabulary-index.md)
- [Deepgram's Docs](../index.md)
- [Deployment](./deployment-index.md)
- [Docker/Podman](./docker-podman-index.md)
- [Features](./features-index.md)
- [Flux TTS](./flux-tts-index.md)
- [Formatting](./formatting-index.md)

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