Voice Messages (STT + TTS) for OpenClaw 🎙️

Complete voice message setup using faster-whisper for transcription and Edge TTS for voice replies.

What we configure

✅ STT (Speech-to-Text) — transcribe voice messages via faster-whisper
✅ TTS (Text-to-Speech) — voice replies via Edge TTS
🎯 Result: voice → text → reply with voice

Installation

1. Create virtual environment (venv)

For Ubuntu create an isolated venv:

python3 -m venv ~/.openclaw/workspace/voice-messages

2. Install faster-whisper

Install packages in venv:

~/.openclaw/workspace/voice-messages/bin/pip install faster-whisper

What gets installed:

faster-whisper — Python library for transcription
Dependencies: ctranslate2, onnxruntime, huggingface-hub, av, numpy, and others.
Size: ~250 MB

Transcription Script

Path and content

File: ~/.openclaw/workspace/voice-messages/transcribe.py

#!/usr/bin/env python3
import argparse
from faster_whisper import WhisperModel


def transcribe(audio_path: str, model_name: str = "small", lang: str = "en", device: str = "cpu") -> str:
    model = WhisperModel(
        model_name,
        device=device,
        compute_type="int8" if device == "cpu" else "float16",
    )
    segments, _ = model.transcribe(audio_path, language=lang, vad_filter=True)
    text = " ".join(seg.text.strip() for seg in segments if seg.text and seg.text.strip()).strip()
    return text


def main():
    p = argparse.ArgumentParser()
    p.add_argument("--audio", required=True)
    p.add_argument("--model", default="small")
    p.add_argument("--lang", default="en")
    p.add_argument("--device", default="cpu", choices=["cpu", "cuda"])
    args = p.parse_args()

    text = transcribe(args.audio, args.model, args.lang, args.device)
    print(text if text else "")


if __name__ == "__main__":
    main()

What the script does:

Accepts audio file path (--audio)
Loads Whisper model (--model): small by default
Sets language (--lang): en for English
Transcribes with VAD filter (Voice Activity Detection)
Outputs clean text to stdout

Make file executable:

chmod +x ~/.openclaw/workspace/voice-messages/transcribe.py

OpenClaw Configuration

1. Configure STT (`tools.media.audio`)

Add to ~/.openclaw/openclaw.json:

{
  "tools": {
    "media": {
      "audio": {
        "enabled": true,
        "maxBytes": 20971520,
        "models": [
          {
            "type": "cli",
            "command": "~/.openclaw/workspace/voice-messages/bin/python",
            "args": [
              "~/.openclaw/workspace/voice-messages/transcribe.py",
              "--audio",
              "{{MediaPath}}",
              "--lang",
              "en",
              "--model",
              "small"
            ],
            "timeoutSeconds": 120
          }
        ]
      }
    }
  }
}

Parameters:

Parameter	Value	Description
`enabled`	`true`	Enable audio transcription
`maxBytes`	`20971520`	Max file size (20 MB)
`type`	`"cli"`	Model type: CLI command
`command`	Python path	Path to python in venv
`args`	argument array	Arguments for script
`{{MediaPath}}`	placeholder	Replaced with audio file path
`timeoutSeconds`	`120`	Transcription timeout (2 minutes)

2. Configure TTS (`messages.tts`)

Add to ~/.openclaw/openclaw.json:

{
  "messages": {
    "tts": {
      "auto": "inbound",
      "provider": "edge",
      "edge": {
        "voice": "en-US-JennyNeural",
        "lang": "en-US"
      }
    }
  }
}

Parameters:

Parameter	Value	Description
`auto`	`"inbound"`	Key mode! — reply with voice only on incoming voice messages
`provider`	`"edge"`	TTS provider (free, no API key)
`voice`	`"en-US-JennyNeural"`	Voice (see available below)
`lang`	`"en-US"`	Locale (en-US for US english)

3. Full configuration example

{
  "tools": {
    "media": {
      "audio": {
        "enabled": true,
        "maxBytes": 20971520,
        "models": [
          {
            "type": "cli",
            "command": "~/.openclaw/workspace/voice-messages/bin/python",
            "args": [
              "~/.openclaw/workspace/voice-messages/transcribe.py",
              "--audio",
              "{{MediaPath}}",
              "--lang",
              "en",
              "--model",
              "small"
            ],
            "timeoutSeconds": 120
          }
        ]
      }
    },
  },
  "messages": {
    "tts": {
      "auto": "inbound",
      "provider": "edge",
      "edge": {
        "voice": "en-US-JennyNeural",
        "lang": "en-US"
      }
    },
    "ackReactionScope": "group-mentions"
  }
}

Apply Changes

Restart Gateway

# Method 1: via openclaw CLI
openclaw gateway restart

# Method 2: via systemd
systemctl --user restart openclaw-gateway

# Check status
systemctl --user status openclaw-gateway
# Should show: active (running)

Testing

Test STT (transcription)

Action: Send a voice message to your Telegram bot

Expected result:

[Audio] User text: [Telegram ...] <media:audio> Transcript: <transcribed text>

Example response:

[Audio] User text: [Telegram kd (@someuser) id:12345678 +5s ...] <media:audio> Transcript: Hello. How are you?

Test TTS (voice replies)

Action: After successful transcription, bot should send a voice reply

Expected result:

Voice file arrives in Telegram
Voice note (round bubble)

Expected behavior:

Incoming voice → bot replies with voice
Text messages → bot replies with text (this is normal!)

Available Edge TTS Voices

Female voices

Voice	ID	Usage example
Jenny	`en-US-JennyNeural`	← current
Ana	`en-US-AnaNeural`	Softer

Male voices

Voice	ID	Usage example
Dmitry	`en-US-RogerNeural`	More bass

How to change voice:

cat ~/.openclaw/openclaw.json | \
  jq '.messages.tts.edge.voice = "en-US-MichelleNeural"' > ~/.openclaw/openclaw.json.tmp
mv ~/.openclaw/openclaw.json.tmp ~/.openclaw/openclaw.json
systemctl --user restart openclaw-gateway

Additional Edge TTS Parameters

Adjusting speed, pitch, volume

{
  "messages": {
    "tts": {
      "edge": {
        "voice": "en-US-JennyNeural",
        "lang": "en-US",
        "rate": "+10%",      // Speed: -50% to +100%
        "pitch": "-5%",     // Pitch: -50% to +50%
        "volume": "+5%"     // Volume: -100% to +100%
      }
    }
  }
}

Troubleshooting

Problem: Voice not transcribed

Logs show:

[ERROR] Transcription failed

Possible causes:

File too large — > 20 MB

# Solution: Increase maxBytes in config
maxBytes: 52428800  # 50 MB

Timeout — transcription took > 2 minutes

# Solution: Increase timeoutSeconds
timeoutSeconds: 180  # 3 minutes

Model not downloaded — first run

# Solution: Wait while it downloads (1-2 minutes)
# Models are cached in ~/.cache/huggingface/

Problem: No voice reply

Possible causes:

Reply too short (< 10 characters)
- TTS skips very short replies
- Solution: this is expected behavior
auto: "inbound" but text message
- TTS in inbound mode replies with voice only on voice messages
- Text messages get text replies — this is correct!

Edge TTS unavailable

# Check
curl -s "https://speech.platform.bing.com/consumer/api/v1/tts" | head -c 100
# If error — temporarily unavailable

Performance

Transcription time (Raspberry Pi 4/ARM)

Whisper Model	Est. time	Quality
`tiny`	~5-10 sec	Low
`base`	~10-20 sec	Medium
`small`	~20-40 sec	High ← current
`medium`	~40-80 sec	Very high
`large`	~80-160 sec	Maximum

Recommendation: For Raspberry Pi use small or base. medium/large will be very slow.

Where Whisper models are stored

~/.cache/huggingface/

Models download automatically on first run.

Done! 🎉

After completing these steps:

✅ faster-whisper installed in venv
✅ transcribe.py script created
✅ OpenClaw configured (STT + TTS)
✅ Gateway restarted
✅ Voice messages working

Now your Telegram bot:

🎙️ Accepts voice → transcribes via faster-whisper
🎤 Replies with voice → generates via Edge TTS
💬 Accepts text → replies with text (as usual)

Useful links:

OpenClaw docs: https://docs.openclaw.ai
TTS docs: https://docs.openclaw.ai/tts
Audio docs: https://docs.openclaw.ai/nodes/audio
Install skills: npx clawhub search voice

Created: 2026-03-01 for OpenClaw 2026.2.26