Cartesia
Add Cartesia text-to-speech to Bolna voice agents for ultra-fast, natural sounding voice output. Built from the ground up for real-time phone conversations.
How Cartesia fits in the stack
Best for
Natural delivery, tone, and response speed on live calls.
Use this layer when
You care about voice quality, expressiveness, or low-latency playback.
Connects to
LLM output upstream and the phone network downstream.
Text-to-speech is the speaking layer
This provider turns the agent’s response into audio the caller hears. It affects brand perception, caller comfort, and how quickly the next utterance can begin.
Telephony
Phone Network
→
STT
Listener
→
LLM
Reasoning
→
TTS
Voice
→
Tools
Actions
This page focuses on where Cartesia fits in a production voice stack. For full setup steps, credentials, and API details, use the documentation link above.
Overview
Cartesia delivers low latency text-to-speech that is made for real-time voice applications. With Bolna's Cartesia integration, you can build voice agents with near-instantaneous speech synthesis, creating natural, flowing conversations without visible delays.
Cartesia's TTS achieves sub-300ms latency from text input to audio output, which is critical for maintaining natural conversation rhythm where even small delays can feel awkward to callers.
Features & Use Cases
Ultra-Fast Responses (Under 300ms)
Cartesia generates speech in less than 300 milliseconds. This removes awkward pauses and keeps conversations flowing naturally.
Real-Time Audio Streaming
Audio plays as it is being created. This lets voice agents start talking even before the whole sentence is ready, making interactions feel instant and real.
Natural, Human-Like Voices
Even though it's incredibly fast, Cartesia sounds like a real person with natural tone, emotion, and rhythm.
Lots of Voice Choices
Pick from a wide variety of voices, accents, and styles to perfectly match your brand.
Built for Phone Calls
Optimized specifically for real-time voice applications like phone calls, ensuring smooth and delay-free conversations.
Use Case: Fast-Paced Customer Support
Perfect for busy customer service calls where quick, clear answers keep customers happy and help resolve issues faster.
Use Case: Financial Services & Trading
Ideal for high stakes trading or banking support where every second matters and delays cause frustration.
Use Case: Urgent Response Lines
Great for emergency or urgent situations where fast communication is needed to deliver critical information immediately.
Other providers in this layer
- Synthesizer ElevenLabs
Give your Bolna voice agents lifelike speech with ElevenLabs. Clone a custom voice or pick from a large library of expressive, natural sounding options. - Synthesizer Rime
Use Rime neural speech synthesis with Bolna voice agents for expressive, natural sounding voices. High quality TTS that makes phone conversations engaging. - Synthesizer Sarvam AI (TTS)
Full Indian language AI stack for Bolna voice agents. LLM, speech-to-text, and text-to-speech tuned for Hindi, Tamil, Telugu, Kannada, and 10+ languages.
See where Cartesia fits in your production workflow
Use the demo to walk through provider selection, stack tradeoffs, and the exact workflow you want Bolna to automate.