Cartesia Sonic 3 TTS

Multilingual text-to-speech with 42 languages, voice cloning, and low latency streaming

🎯 Cartesia Sonic 3: Multilingual Excellence

High-quality, low-latency TTS with support for 42 languages, voice cloning from ~5 second samples, and WebSocket streaming. Perfect for global deployments and multilingual voice agents.

Quick Setup

1. Get API Key

   1. Visit Cartesia.ai and create an account
   2. Navigate to your API settings
   3. Copy your API key
2. Configure in Burki

   1. Go to AI Configuration → TTS tab
   2. Select Cartesia Sonic 3 as provider
   3. Paste your API key in the TTS API Key field
3. Choose Voice & Model

   Select your preferred model and voice from the dropdowns

Pricing: Cartesia charges approximately $0.015 per 1,000 characters. Check their website for current pricing details.

Available Models

⚡ sonic-3

Latest Model (Auto-updates)

Always uses the newest Sonic 3 improvements

Languages: 42 languages Best for: Most applications, staying current

📌 sonic-3-2025-10-27

Stable Snapshot

Fixed version for consistent behavior

Languages: 42 languages Best for: Production stability, testing

Recommendation: Use sonic-3 for development and most use cases. Use the dated snapshot for production if you need guaranteed consistency.

Available Voices

Preset Voices

Female Voices

Katie

Stable & Realistic

Perfect for voice agents

Voice ID: f786b574-daa5-4673-aa0c-cbe3e8534c02

Tessa

Emotive & Expressive

Great for engaging conversations

Voice ID: 6ccbfb76-1fc6-48f7-b71d-91ac6298247b

Sarah

Clear & Professional

Ideal for business applications

Voice ID: a0e99841-438c-4a64-b679-ae501e7d6091

Male Voices

Kiefer

Stable & Realistic

Perfect for voice agents

Voice ID: 228fca29-3a0a-435c-8728-5cb483251068

Kyle

Emotive & Expressive

Great for dynamic interactions

Voice ID: c961b81c-a935-4c17-bfb3-ba2239de8c2f

All Available Voices

Voice	Gender	Style	Voice ID	Best For
Katie	Female	Stable, Realistic	f786b574-daa5-4673-aa0c-cbe3e8534c02	Voice agents
Kiefer	Male	Stable, Realistic	228fca29-3a0a-435c-8728-5cb483251068	Voice agents
Tessa	Female	Emotive, Expressive	6ccbfb76-1fc6-48f7-b71d-91ac6298247b	Characters
Kyle	Male	Emotive, Expressive	c961b81c-a935-4c17-bfb3-ba2239de8c2f	Characters
Sarah	Female	Clear, Professional	a0e99841-438c-4a64-b679-ae501e7d6091	Business

Language Support

42 Languages Supported: Cartesia Sonic 3 offers extensive multilingual support, making it ideal for global deployments.

Supported Languages

🇺🇸 English

en

🇪🇸 Spanish

es

🇫🇷 French

fr

🇩🇪 German

de

🇮🇹 Italian

it

🇵🇹 Portuguese

pt

🇨🇳 Chinese

zh

🇯🇵 Japanese

ja

🇰🇷 Korean

ko

🇮🇳 Hindi

hi

🇸🇦 Arabic

ar

🇷🇺 Russian

ru

Additional Languages: Dutch (nl), Polish (pl), Swedish (sv), Turkish (tr), Tagalog (tl), Bulgarian (bg), Romanian (ro), Czech (cs), Greek (el), Finnish (fi), Croatian (hr), Malay (ms), Slovak (sk), Danish (da), Tamil (ta), Ukrainian (uk), Hungarian (hu), Norwegian (no), Vietnamese (vi), Bengali (bn), Thai (th), Hebrew (he), Georgian (ka), Indonesian (id), Telugu (te), Gujarati (gu), Kannada (kn), Malayalam (ml), Marathi (mr), Punjabi (pa)

Voice Cloning

Cartesia supports creating custom voices from audio samples.

Quick Cloning: Create a custom voice from just ~5 seconds of clean audio.

Requirements

Requirement	Value
Audio Duration	~5 seconds (recommended)
Formats	MP3, WAV, FLAC, M4A, OGG
Max File Size	10MB
Sample Rate	16kHz minimum recommended
Channels	Mono preferred
Quality	Clean audio without background noise

Clone a Voice

1. Prepare Audio Sample

   Record or select ~5 seconds of clear speech from the target voice

2. Upload via UI

   1. Go to Voice Configuration in assistant settings
   2. Select Cartesia as provider
   3. Click Clone Voice button
   4. Upload your audio sample
3. Use Cloned Voice

   The cloned voice appears in your voice dropdown and can be selected for your assistant

Voice Cloning Tips

Configuration Options

Context Continuation

Cartesia maintains natural prosody across sentences using context continuation:

# First sentence starts new context
message = {
    "context_id": "ctx_0",
    "continue": False,  # New context
    "transcript": "Hello, welcome to our service."
}

# Subsequent sentences continue the context
message = {
    "context_id": "ctx_0", 
    "continue": True,  # Continue same context
    "transcript": "How can I help you today?"
}

Flush Tags

Force immediate speech mid-sentence using the <flush/> tag:

# Text with flush tag
text = "Please hold<flush/> while I check your account."
# "Please hold" speaks immediately, then "while I check..." follows

Audio Format

Cartesia automatically outputs the appropriate format for your telephony provider:

• Twilio/Telnyx: PCM μ-law @ 8kHz
• Vonage: PCM 16-bit @ 16kHz

API Integration

Python

from app.services.tts.tts_cartesia import CartesiaTTSService

# Create Cartesia TTS instance
tts = CartesiaTTSService(
    call_sid="unique_call_id",
    api_key="your_cartesia_api_key",
    voice_id="f786b574-daa5-4673-aa0c-cbe3e8534c02",  # Katie
    model_id="sonic-3",
    language="en"
)

# Start session
await tts.start_session(audio_callback=your_callback)

# Process text
await tts.process_text("Hello, this is a test.")

# End session
await tts.end_session()

Performance Comparison

Feature	Cartesia Sonic 3	ElevenLabs	Deepgram Aura
Latency	~150ms	~250ms	~75ms
Languages	42	70+	English + Spanish
Voice Quality	High	Premium	Good
Voice Cloning	Yes (~5 sec)	Yes (1-25 min)	No
Best For	Multilingual agents	Premium quality	Speed-focused

Common Issues & Solutions

Connection Issues

Problem: WebSocket connection fails

Solutions:

• Verify your CARTESIA_API_KEY is set correctly
• Check network connectivity to api.cartesia.ai
• Ensure API key has sufficient credits

Voice Not Found

Problem: Selected voice doesn’t work

Solutions:

• Verify you’re using a valid voice ID (UUID format)
• If using a custom cloned voice, ensure it exists in your Cartesia account
• Try one of the preset voices to test connectivity

Audio Quality Issues

Problem: Output sounds distorted or unclear

Solutions:

• Cartesia outputs 8kHz μ-law for Twilio compatibility
• For higher quality, ensure you’re using the correct output format for your use case
• Check that your telephony provider supports the audio format

See Also

⚡ Need Speed?

Deepgram Aura - Ultra-low ~75ms latency for real-time calls

🎭 Premium Quality?

ElevenLabs - Industry-leading voice quality with 70+ languages

🔗 Additional Resources

Official Documentation: Cartesia Docs

Voice Cloning: Clone API Reference

WebSocket API: TTS WebSocket Guide

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🚀 Ready to Use Cartesia?

Head back to your assistant configuration and set up Cartesia Sonic 3 for multilingual voice experiences!