Speech-to-speech (EVI)

Hume’s Empathic Voice Interface (EVI) is an advanced, real-time emotionally intelligent voice AI. EVI measures users’ nuanced vocal modulations and responds to them using a speech-language model, which guides language and speech generation.

By processing the tune, rhythm, and timbre of speech, EVI unlocks a variety of new capabilities, like knowing when to speak and generating more empathic language with the right tone of voice.

These features enable smoother and more satisfying voice-based interactions between humans and AI, opening new possibilities for personal AI, customer service, accessibility, robotics, immersive gaming, VR experiences, and much more.

EVI features

Basic capabilities

Empathic AI Features

Quickstart

Kickstart your integration with our quickstart guides for Next.js, TypeScript, and Python. Each guide walks you through integrating the EVI API, capturing user audio, and playing back EVI’s response so you can get up and running quickly.

Building with EVI

EVI chat sessions run over a real-time WebSocket connection, enabling fluid, interactive dialogue. Users speak naturally while EVI analyzes their vocal expression and responds with emotionally intelligent speech.

Authentication

REST endpoints support the API key authentication strategy. specify your API key in the X-HUME-API-KEY header of your request.

The EVI WebSocket endpoint supports both the API key and Token authentication strategies, specify your API key or Access token in the query parameters of your request.

Configuration

Before starting a session, you’ll need a voice and a configuration.

• Design a voice, clone an existing one, or select one from Hume’s extensive Voice Library.
• Build an EVI configuration to define system behavior, voice selection, and other settings.

Connection

The EVI Playground is the easiest way to test your configuration. It lets you speak directly with EVI using your selected voice and settings, without writing any code.

To begin a conversation, connect using the EVI WebSocket URL start streaming the user’s audio input, via audio_input messages. EVI responds in real time with a sequence of structured messages:

• user_message: Message containing a transcript of the user’s message along with their vocal expression measures
• assistant_message: Message containing EVI’s response content.
• audio_output: EVI’s response audio corresponding with the assistant_message
• assistant_end: Message denoting the end of EVI’s response.

Developer tools

Hume provides a suite of developer tools to integrate and customize EVI.

API limits

The following limits apply to Hume’s Speech-to-Speech (EVI) API.

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