Overview
Sarvam AI launched Bulbul V4 Flash on October 13, 2026, a real-time text-to-speech model for 11 Indian languages with under 250 ms time-to-first-audio.
It costs Rs. 20 per 10,000 characters, one-third less than V3, with a half-price offer of Rs. 10 until November 12, 2026.
Developers can start through the Sarvam API, Playground, or Content Studio, and pick REST, HTTP streaming, or WebSocket based on how live the use case is.
Sarvam AI launched Bulbul V4 Flash on October 13, 2026, targeting a gap in India's voice technology market. Many speech tools sound stiff in regional languages and lag in live calls.
Sarvam, the Indian AI lab, built this model to speak 11 languages with natural pacing and start audio in under 250 milliseconds. This guide explains what the model does, what it costs, and how developers can start using it today.
What Bulbul V4 Flash is and Why Sarvam Built It
Bulbul V4 Flash is a text-to-speech model from Sarvam AI. It turns written text into spoken audio and targets real-time uses such as customer support, banking calls, payment reminders, and sales calls.
The model is a smaller, distilled version of Sarvam’s larger research work. It handles regional accents, Indian English, names, numbers, and mixed-language speech such as Hinglish.
A new text normalization layer reads currency amounts, acronyms, and IDs the way a person would say them. Sarvam describes its goal as “not just speaking India’s languages, but speaking them the way India does.”
Sarvam also runs a Sarvam AI LLM line, including Sarvam 105B, along with speech-to-text and vision models. Together, they make it a key name among Indian AI model builders.
Also read: Sarvam Becomes India's Newest AI Unicorn With USD 234 Million Funding Led by HCLTech
Speed, Price, and Language Numbers Worth Knowing
Sarvam reports time-to-first-audio under 250 milliseconds in production. It also says the model runs up to 40 percent faster than Bulbul V3 under similar load.
Pricing sits at Rs. 20 per 10,000 characters, down from Rs. 30 for V3, which is a one-third cut. A launch offer halves the rate to Rs. 10 until November 12, 2026. At the offer price, a team that voices 1 million characters a month would pay about Rs. 1,000, or Rs. 2,000 at the standard rate.
The model covers 11 languages: Hindi, Bengali, Gujarati, Kannada, Malayalam, Marathi, Odia, Punjabi, Tamil, Telugu, and Indian English. It ships with 83 voices and 224 voice-and-style options. Sarvam also grew its speech data to nearly seven times the V3 amount.
Sarvam says compact models can blur speech patterns across languages, so it trained V4 from scratch with Indian languages as the main goal.
How Developers Can Start Using the Sarvam API
Access takes four steps. First, developers sign up at the Sarvam dashboard and create an API key. Next, they pick the model ID, bulbul:v4-flash. Then they set the language code, choose a voice, and send the text. The API returns audio in the chosen format.
Non-coders can test the voices first in the Sarvam Playground or Content Studio. Teams that use AI coding tools can also add Sarvam’s text-to-speech skill to generate working code. Output formats include MP3, WAV, AAC, Opus, FLAC, and phone-line options such as mu-law and A-law. Sarvam also publishes migration guides for teams moving from ElevenLabs, Cartesia, Deepgram, or Gemini.
Choosing Between REST, HTTP Streaming, and WebSocket
The REST API suits short jobs, with a limit of 2,500 characters per request. HTTP streaming allows up to 3,500 characters and sends audio as it is made. WebSocket fits live voice agents that need back-and-forth talk.
Sarvam advises keeping WebSocket messages under 500 characters for the lowest delay. The default sample rate is 22,050 Hz, and 8,000 Hz suits phone lines. Developers can also tune speed, tone, and loudness, and add a pronunciation dictionary for brand names.
Integrations exist for LiveKit, Pipecat, Twilio, Exotel, and Vapi, so teams can plug the voice into existing call systems.
Best Uses & Limits of this Indian AI Model
Contact centers, banks, and education apps stand to gain most. A loan reminder in Tamil or a scheme update in Marathi can sound local instead of robotic, which may build trust with callers. Voice quality shapes trust in automated calls, so natural pacing is a business factor, not a nice extra.
Limits matter too. Language coverage is 11, not all 22 official Indian languages, and the speed and quality claims come from Sarvam, so teams should test with their own scripts. Sarvam has also previewed Bulbul V4 Pro for richer speech, but it has shared no date or price.
Why this Sarvam AI Voice Model is Worth a Test
The Sarvam AI voice model gives Indian businesses a faster and cheaper way to talk to customers in their own language. It offers 11 languages, 83 voices, under 250 milliseconds to first audio, and a price of Rs. 20 per 10,000 characters.
Small tests with real scripts will show how well it handles names, numbers, and Hinglish. For teams building voice bots, this Indian AI model deserves a place on the shortlist.
FAQs
1. What is Sarvam AI Bulbul V4 Flash?
It is a text-to-speech model from Sarvam AI that turns text into natural speech for real-time uses such as customer support, banking calls, and sales calls.
2. Which languages does it support?
It supports 11 languages: Hindi, Bengali, Gujarati, Kannada, Malayalam, Marathi, Odia, Punjabi, Tamil, Telugu, and Indian English. It also handles mixed speech such as Hinglish.
3. How much does it cost?
The standard price is Rs. 20 per 10,000 characters. A launch offer cuts it to Rs. 10 until November 12, 2026.
4. How can developers start using it?
Developers create an API key on the Sarvam dashboard, use the model ID bulbul:v4-flash, set the language and voice, and send text through the REST, HTTP streaming, or WebSocket API. They can also test voices in the Playground or Content Studio.
5. Is it better than Bulbul V3?
Sarvam says V4 Flash is up to 40 percent faster, one-third cheaper, and better in speech quality. These claims come from Sarvam, so teams should test it with their own content.