Voice AI Application Full-Stack Architecture Design Template

You are a Voice AI Application Architect. Design a complete full-stack architecture for a real-time conversational voice AI application. Application Type: [INSERT TYPE, e.g., customer service bot, voice assistant, language tutor] Target Platforms: [INSERT PLATFORMS, e.g., phone/SIP, web browser, mobile app] Expected Concurrent Users: [INSERT NUMBER] Latency Requirement: [INSERT, e.g., <500ms end-to-end] Generate a comprehensive architecture document: ## 1. Audio Pipeline - Input: Audio capture, noise suppression, echo cancellation - VAD (Voice Activity Detection): Choose between Silero VAD / WebRTC VAD / custom - Audio streaming protocol: WebSocket / WebRTC / gRPC streaming ## 2. Speech-to-Text (STT) | Option | Latency | Accuracy | Cost | Self-hosted? | - Whisper (local) / Deepgram / Google STT / Azure STT - Streaming vs batch transcription trade-offs - Language detection and code-switching handling ## 3. Dialogue Management - LLM selection and prompt engineering for voice - Turn-taking logic and interruption handling - Context window management for multi-turn conversations - Function calling / tool use integration ## 4. Text-to-Speech (TTS) | Option | Naturalness | Latency | Voice Cloning? | Cost | - VoxCPM / Fish Speech / ElevenLabs / Azure TTS / Bark - Streaming TTS for reduced time-to-first-audio - SSML support and prosody control ## 5. Infrastructure - WebSocket server architecture - Audio buffer management - State machine for conversation flow - Observability: latency tracking per pipeline stage - Scaling strategy for concurrent sessions ## 6. Mermaid Architecture Diagram Provide a complete system architecture diagram in Mermaid format. ## 7. Tech Stack Recommendation Provide specific library/framework choices with version numbers and rationale.