LMNT

LMNT is a venture-backed AI speech synthesis company founded by Sharvil Nanavati, who previously led the team that built Google Glass. The company focuses exclusively on solving the hardest problems in real-time speech production: achieving human-level naturalness while maintaining the ultra-low latency required for fluid conversation.

LMNT's text-to-speech models deliver response times of 150-200ms—fast enough to feel like natural human dialogue. The platform produces expressive speech with accurate prosody, capturing the rhythm, intonation, and emotional nuance that makes voices sound authentically human rather than robotic. Their architecture combines techniques from image synthesis and language modeling to achieve high-quality output without the hallucinations or repetition issues common in other approaches.

The platform supports 24 languages with seamless mid-sentence switching, reflecting how multilingual speakers naturally communicate. Voice cloning requires only 5 seconds of audio to produce studio-quality results. LMNT powers Khan Academy's Khanmigo AI tutor, HeyGen's video platform, Unity game developers, and Vercel's AI integration ecosystem.

LMNT is a native voice provider within Vapi's platform, enabling developers to build conversational AI agents with best-in-class speech synthesis. The integration delivers LMNT's sub-200ms text-to-speech directly into Vapi voice pipelines, creating the responsive, natural interactions that users expect from human conversation.

When a Vapi agent generates a response, LMNT's streaming API begins producing audio immediately, minimizing the silence between turns that makes AI conversations feel stilted. This real-time capability is essential for applications like phone-based customer service, where latency directly impacts caller satisfaction and completion rates.

Developers using Vapi with LMNT can clone custom voices to create branded agent personas, or select from LMNT's pre-built voice library optimized for conversational delivery. The integration supports telephony-standard audio formats, enabling seamless deployment across phone systems, web applications, and mobile interfaces.