Azure Speech Text-to-Speech Provider

Azure Speech is a bundled provider for Azure AI Speech text-to-speech. OpenClaw communicates directly with the Azure Speech REST API using SSML, producing MP3 for standard replies, native Ogg/Opus for voice notes, and 8 kHz mulaw for telephony channels like Voice Call. The request includes the provider-owned output format via the X-Microsoft-OutputFormat header.

Detail	Value
Provider ID	`azure-speech` (alias: `azure`)
Website	Azure AI Speech
Docs	Speech REST text-to-speech
Auth	`AZURE_SPEECH_KEY` plus `AZURE_SPEECH_REGION`
Default voice	`en-US-JennyNeural`
Default file output	`audio-24khz-48kbitrate-mono-mp3`
Default voice-note file	`ogg-24khz-16bit-mono-opus`

Getting started

Create an Azure Speech resource

In the Azure portal, set up a Speech resource. Copy KEY 1 from Resource Management > Keys and Endpoint, and copy the resource location, for example eastus.

AZURE_SPEECH_KEY=<speech-resource-key>
AZURE_SPEECH_REGION=eastus

Select Azure Speech in tts

{
  tts: {
    auto: "always",
    provider: "azure-speech",
    providers: {
      "azure-speech": {
        voice: "en-US-JennyNeural",
        lang: "en-US",
      },
    },
  },
}

Send a message

Send a reply over any connected channel. OpenClaw generates the audio using Azure Speech and delivers MP3 for standard audio, or Ogg/Opus when the channel expects a voice note.

Configuration options

All options are located under tts.providers["azure-speech"].

Option	Description
`apiKey`	Azure Speech resource key. Falls back to `AZURE_SPEECH_KEY`, `AZURE_SPEECH_API_KEY`, or `SPEECH_KEY`.
`region`	Azure Speech resource region. Falls back to `AZURE_SPEECH_REGION` or `SPEECH_REGION`.
`endpoint`	Optional Azure Speech endpoint override. Falls back to trusted `AZURE_SPEECH_ENDPOINT`.
`baseUrl`	Optional Azure Speech base URL override.
`voice`	Azure voice ShortName (default `en-US-JennyNeural`). Legacy alias: `voiceId`.
`lang`	SSML language code (default `en-US`).
`outputFormat`	Audio-file output format (default `audio-24khz-48kbitrate-mono-mp3`).
`voiceNoteOutputFormat`	Voice-note output format (default `ogg-24khz-16bit-mono-opus`).
`timeoutMs`	Request timeout override in milliseconds. Falls back to the global `tts.timeoutMs`.

The provider is considered configured once apiKey is set along with one of region, endpoint, or baseUrl. Environment variables are only checked as a fallback for config keys that are not set. Workspace .env files cannot set AZURE_SPEECH_ENDPOINT; use the process environment, global runtime dotenv, or explicit config for endpoint routing.

Notes

Authentication

Azure Speech requires a Speech resource key, not an Azure OpenAI key. The key is sent as Ocp-Apim-Subscription-Key; OpenClaw derives https://<region>.tts.speech.microsoft.com from region unless you supply endpoint or baseUrl.

Voice names

Use the Azure Speech voice ShortName value, for example en-US-JennyNeural. The bundled provider can list voices through the same Speech resource and excludes voices marked as deprecated, retired, or disabled.

Audio outputs

Azure accepts output formats like audio-24khz-48kbitrate-mono-mp3, ogg-24khz-16bit-mono-opus, and riff-24khz-16bit-mono-pcm. OpenClaw requests Ogg/Opus for voice-note targets so channels can send native voice bubbles without an extra MP3 conversion, and forces raw-8khz-8bit-mono-mulaw for telephony targets.

Alias

azure is accepted as a provider alias for existing config, but new config should use azure-speech to avoid confusion with Azure OpenAI model providers.

Text-to-speech, TTS overview, providers, and tts config.
Configuration, Full config reference including tts settings.
Providers, All bundled OpenClaw providers.
Troubleshooting, Common issues and debugging steps.