Vapi partners with Hume AI to offer developers the most affordable emotionally intelligent voice for phone calling
By Serena Wang on July 29, 2025
Vapi's platform serves developers building conversational voice agents in phone calling applications. Through a close partnership with Hume AI, they've integrated Hume's Octave TTS to offer developers real-time expressive text-to-speech at 150ms latency and 2¢/minute pricing, delivering significant performance and cost improvements over previous solutions.
The Vapi platform
Vapi streamlines voice agent development with phone calling infrastructure that handles the complex orchestration of separate models for speech recognition, language, and voice synthesis. Their platform allows developers to focus on application logic rather than technical implementation, serving as a comprehensive solution for building, testing, and deploying conversational AI applications. With a commitment to providing developers flexibility in choosing the best tools for their projects, Vapi continuously optimizes their integrations for speed, reliability, and affordability.
Why EVI stands out on Vapi's platform
When Vapi evaluated voice providers for their developer community, they worked closely with Hume to optimize the integration for maximum developer value:
-
41% cost reduction: Hume's 2¢/minute pricing represents a significant cost savings compared to other expressive TTS options on the platform
-
66% latency improvement: The optimized integration delivers 150ms response times, representing a major performance boost over previous implementations
-
Enhanced expressiveness: Hume's Octave TTS provides natural, emotionally aware voice output that adapts to conversational context
Developer adoption and technical advantages
Vapi's developer community has adopted EVI for projects where realistic, expressive speech and cost efficiency are priorities. The integration provides a straightforward path to adding expressive voice capabilities without the typical complexity of building emotional AI from scratch.
Developers building across various industries are exploring Hume's potential for applications ranging from healthcare and customer service to education and personal assistants, drawn by the combination of affordability and emotional expressiveness available through Vapi's platform.
"Vapi shares our vision of making advanced voice AI accessible to every developer. This optimized integration proves that you don't have to choose between emotional intelligence and practical constraints like cost and speed—you can have both." — Alan Cowen, CEO at Hume AI
Start building with EVI today
EVI is available now on Vapi's platform, offering developers an affordable way to add emotionally intelligent voice to their phone calling applications while maintaining the fast response times users expect.
Subscribe
Sign up now to get notified of any updates or new articles.
