Azure Speech is an Azure AI Speech text-to-speech provider. In OpenClaw it synthesizes outbound reply audio as MP3 by default, native Ogg/Opus for voice notes, and 8 kHz mulaw audio for telephony channels such as Voice Call.

OpenClaw uses the Azure Speech REST API directly with SSML and sends the provider-owned output format through X-Microsoft-OutputFormat.

Detail	Value
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, create a Speech resource. Copy **KEY 1** from
Resource Management > Keys and Endpoint, and copy the resource location
such as `eastus`.

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

Select Azure Speech in messages.tts

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "azure-speech",
      providers: {
        "azure-speech": {
          speakerVoice: "en-US-JennyNeural",
          lang: "en-US",
        },
      },
    },
  },
}
```

Send a message

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

Configuration options

Option	Path	Description
apiKey	messages.tts.providers.azure-speech.apiKey	Azure Speech resource key. Falls back to AZURE_SPEECH_KEY, AZURE_SPEECH_API_KEY, or SPEECH_KEY.
region	messages.tts.providers.azure-speech.region	Azure Speech resource region. Falls back to AZURE_SPEECH_REGION or SPEECH_REGION.
endpoint	messages.tts.providers.azure-speech.endpoint	Optional Azure Speech endpoint/base URL override.
baseUrl	messages.tts.providers.azure-speech.baseUrl	Optional Azure Speech base URL override.
speakerVoice	messages.tts.providers.azure-speech.speakerVoice	Azure voice ShortName (default en-US-JennyNeural). Legacy alias: voice.
lang	messages.tts.providers.azure-speech.lang	SSML language code (default en-US).
outputFormat	messages.tts.providers.azure-speech.outputFormat	Audio-file output format (default audio-24khz-48kbitrate-mono-mp3).
voiceNoteOutputFormat	messages.tts.providers.azure-speech.voiceNoteOutputFormat	Voice-note output format (default ogg-24khz-16bit-mono-opus).

Notes

Authentication

Azure Speech uses 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
provide `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 filters voices marked deprecated or retired.

Audio outputs

Azure accepts output formats such as `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.

Alias

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

Related

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