Hindi Voice Agents

Complete guide to building production Hindi voice agents with optimal STT, TTS, and LLM configurations.

Hindi Voice Agents

Hindi (hi-IN) has excellent support across all major providers, making it ideal for voice agents serving the Indian market.

Quick Start

{
  "agent": {
    "name": "Hindi Support Agent",
    "language": "hi-IN",

    "llmProvider": "gemini-2.5",
    "llmModel": "gemini-2.5-flash-lite",

    "sttProvider": "deepgram",
    "sttModel": "nova-3",

    "ttsProvider": "azure",
    "ttsVoice": "hi-IN-SwaraNeural",

    "greetingMessage": "नमस्ते! मैं आपकी कैसे मदद कर सकता हूँ?",

    "prompt": "आप एक मददगार ग्राहक सेवा एजेंट हैं। हिंदी में जवाब दें।"
  }
}

Provider Options

STT (Speech-to-Text)

Provider Model WER Latency Cost/min
Deepgram nova-3 8-12% ~150ms ₹0.35
Google chirp_2 10-14% ~200ms ₹1.34
ElevenLabs scribe 12-15% ~180ms ₹0.56
Azure speech 12-16% ~220ms ₹0.84

Recommendation: Deepgram Nova-3 for best accuracy and lowest cost.

TTS (Text-to-Speech)

Provider Voices Quality Cost/min
Azure 4 Neural Excellent ₹1.01
Google 2 Neural Good ₹1.34
ElevenLabs Multilingual Good ₹12.60

Recommendation: Azure Neural voices for best quality Hindi speech.

LLM

Provider Model Hindi Understanding Cost/min
Gemini 2.5 flash-lite Excellent ₹0.04
Gemini 2.0 flash Excellent ₹0.05
GPT-4o mini Good ₹0.08

Recommendation: Gemini 2.5 Flash-Lite for best Hindi understanding at lowest cost.

Azure Hindi Voices

Voice Gender Style Best For
hi-IN-SwaraNeural Female Professional, warm Customer support
hi-IN-MadhurNeural Male Professional Business calls
hi-IN-AnanyaNeural Female Conversational Casual interactions
hi-IN-ArjunNeural Male Young, friendly Youth-focused apps

Voice Configuration

{
  "ttsProvider": "azure",
  "ttsVoice": "hi-IN-SwaraNeural",
  "ttsConfig": {
    "speakingRate": 1.0,
    "pitch": "0%"
  }
}

Hinglish (Hindi-English Mix)

For agents that handle code-switching between Hindi and English:

{
  "agent": {
    "name": "Hinglish Agent",
    "language": "hi-IN",

    "sttProvider": "deepgram",
    "sttConfig": {
      "language": "hi",
      "model": "nova-3"
    },

    "prompt": "You are a customer support agent. Respond in Hinglish (Hindi-English mix) as commonly spoken in urban India. Example: 'Aapka order ship ho gaya hai, delivery Friday tak expected hai.'"
  }
}

Hinglish Prompt Tips

## Language Guidelines
- Mix Hindi and English naturally as spoken in urban India
- Use English for technical terms: order, delivery, payment, refund
- Use Hindi for greetings and emotional expressions
- Match the customer's language style

## Examples
Good: "Aapka order successfully place ho gaya hai"
Good: "Main abhi check karta hoon aapka status"
Avoid: Pure formal Hindi that sounds unnatural

Devanagari Script Handling

Prompt in Hindi

{
  "prompt": "आप एक सहायक एजेंट हैं। कृपया ग्राहकों की मदद करें।\n\n## नियम\n- विनम्र रहें\n- स्पष्ट उत्तर दें\n- समस्याओं का समाधान करें"
}

Transliteration Support

Users may type in Roman script:

{
  "prompt": "Users may write Hindi in Roman script (e.g., 'mujhe order status chahiye'). Understand both Devanagari (हिंदी) and Roman transliterations. Always respond in Devanagari script unless the user prefers Roman."
}

Honorifics & Formality

Hindi has formal (आप) and informal (तुम) address:

{
  "prompt": "## Formality Guidelines\n- Always use 'आप' (respectful you) not 'तुम'\n- Add 'जी' suffix for respect: 'हाँ जी', 'नहीं जी'\n- Use formal greetings: 'नमस्ते', 'नमस्कार'\n- Avoid overly casual language"
}

Formal vs Informal

Formal (Business) Informal (Casual)
आप कैसे हैं? तुम कैसे हो?
कृपया बताएं बताओ ना
धन्यवाद थैंक्स
जी, बिल्कुल हाँ हाँ

Number Handling

Hindi uses the Indian numbering system:

{
  "prompt": "When speaking numbers, use Indian format:\n- 1,00,000 = एक लाख (not one hundred thousand)\n- 10,00,000 = दस लाख\n- 1,00,00,000 = एक करोड़\n\nSpell out amounts clearly: '₹1,50,000' as 'एक लाख पचास हज़ार रुपये'"
}

Regional Considerations

Common Hindi Variants

Region Characteristics Notes
Standard Hindi Neutral accent Best for pan-India
Delhi Hindi Urban, English-mixed Common in North
Mumbai Hindi Marathi influence Common in West
Bihari Hindi Regional vocabulary Eastern India

Greeting by Time

func getHindiGreeting(hour int) string {
    switch {
    case hour < 12:
        return "सुप्रभात" // Good morning
    case hour < 17:
        return "नमस्कार" // Good afternoon
    default:
        return "शुभ संध्या" // Good evening
    }
}

Complete Example

Customer Support Agent

{
  "agent": {
    "name": "Hindi Customer Support",
    "language": "hi-IN",

    "llmProvider": "gemini-2.5",
    "llmModel": "gemini-2.5-flash-lite",
    "llmTemperature": 0.7,

    "sttProvider": "deepgram",
    "sttModel": "nova-3",
    "sttConfig": {
      "language": "hi",
      "keywords": ["ऑर्डर:2", "रिफंड:2", "डिलीवरी:2"]
    },

    "ttsProvider": "azure",
    "ttsVoice": "hi-IN-SwaraNeural",

    "greetingMessage": "नमस्ते! मैं आपकी सहायता के लिए हाज़िर हूँ। आप अपने ऑर्डर के बारे में पूछ सकते हैं, या किसी और विषय पर मदद ले सकते हैं।",

    "prompt": "आप एक ग्राहक सहायता एजेंट हैं।\n\n## आपकी भूमिका\n- ग्राहकों की समस्याओं का समाधान करें\n- विनम्र और सहायक रहें\n- स्पष्ट और संक्षिप्त उत्तर दें\n\n## भाषा\n- शुद्ध हिंदी या Hinglish दोनों चलेगी\n- ग्राहक की भाषा शैली को मैच करें\n- 'आप' का प्रयोग करें, 'तुम' नहीं",

    "allowInterruptions": true
  }
}

Testing Hindi Agents

Test Phrases

# Greetings
"नमस्ते"
"हैलो"

# Order queries
"मेरा ऑर्डर कहाँ है?"
"मुझे ऑर्डर स्टेटस चाहिए"
"order number 12345"

# Hinglish
"Mujhe refund chahiye"
"Order kab aayega?"

# Edge cases
"हाँ जी" (short affirmative)
"नहीं नहीं" (repetition)

Common STT Errors

Spoken Misheard As Solution
हाँ हा, हां Add keyword boost
नहीं नई, नहि Post-processing
ऑर्डर आर्डर Custom vocabulary

Cost Optimization

Budget Configuration

{
  "sttProvider": "deepgram",
  "ttsProvider": "google",
  "llmProvider": "gemini-2.5"
}

Estimated cost: ₹0.44/minute

Quality Configuration

{
  "sttProvider": "google",
  "sttModel": "chirp_2",
  "ttsProvider": "azure",
  "llmProvider": "gemini"
}

Estimated cost: ₹2.40/minute

Next Steps