Azure Speech

Azure Speech is a bundled Azure AI Speech text-to-speech provider. OpenClaw calls the Azure Speech REST API directly with SSML, synthesizing MP3 for standard replies, native Ogg/Opus for voice notes, and 8 kHz mulaw for telephony channels such as Voice Call. The request sends the provider-owned output format through 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

1. 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
   
2. Select Azure Speech in messages.tts

   {
     messages: {
       tts: {
         auto: "always",
         provider: "azure-speech",
         providers: {
           "azure-speech": {
             voice: "en-US-JennyNeural",
             lang: "en-US",
           },
         },
       },
     },
   }
   
3. 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

All options live under messages.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 messages.tts.timeoutMs.

The provider is considered configured once apiKey is set plus one of region, endpoint, or baseUrl. Env vars are only checked as a fallback for config keys left unset. 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 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 out voices marked deprecated, retired, or disabled.

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, 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.

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.