Hume EVI Is Shutting Down - Moving Your Voice Characters to Neocortex

Hume is sunsetting the TTS and EVI APIs. The notice sits at the top of Hume's developer documentation: access ends at 12:01 a.m. EST on November 13, 2026, both APIs stay fully supported until then, and any data in your account is permanently deleted after that date.

Hume's Empathic Voice Interface (EVI) was a speech-to-speech API whose replies adapted their tone to how the user sounded. If your game characters run on it, they stop talking on that morning. This guide covers what to save, how EVI concepts map to Neocortex, and how to move one character at a time.

What the Hume EVI shutdown means for your game

Three things break at once:

• Your runtime. Every EVI WebSocket session fails, so characters go silent in builds already in players' hands.
• Your voices. Hume's TTS API goes with EVI, so you cannot fall back to pre-generating lines through Hume either.
• Your configs. Prompts, voice settings and EVI configurations stored in your Hume account are deleted.

Hume never shipped a Unity SDK. Its official SDKs were Python, TypeScript and React, so a game integration was always a custom client you wrote around them. That client is the part you replace. Your character writing is the part worth keeping.

Map your EVI setup to Neocortex

A typical EVI integration has four layers. Here is where each one lands:

The biggest difference is the middle rows. In EVI, a character was a prompt. In Neocortex it is a graph you can read, test and hand to a designer.

Migration in five steps

1. Export what you own

Before anything else, copy every system prompt, config value and voice setting out of your Hume account. Save any generated audio you hold the rights to. After the cut-off, none of it can be recovered.

2. Rebuild the prompt as nodes

Create a free Neocortex account and split each system prompt into nodes:

• Background and role go into the Agent node.
• Facts, lore and reference documents go into Knowledge, as text or uploaded PDF and TXT files.
• Temperament goes into Personality, and the mood the character starts in goes into Emotion.
• Anything the character should do in the game becomes an Intent and an Action.

3. Recreate the voice

Clone the voice from a short recording you have the rights to, or describe it in a sentence and pick from generated voices. Pro includes 5 custom voices and Team includes 20.

4. Test in the browser

Talk to the character in the editor, by text or by voice, until it sounds and behaves like the original. In-editor testing never uses credits, so this step is free.

5. Swap the client

Replace your custom EVI client with the Unity SDK, the Unreal Engine 5 integration, the Godot (beta) plugin, or the Web API from any other stack. Map the emotion tag on each reply to the facial animation or tone cues your game already uses, and wire actions to the scene objects they target.

Most single characters move in an afternoon. Projects with many characters move faster after the first, because the node layout becomes a template.

What players will notice

If the migration goes well, very little. The character keeps its personality and knowledge, speech still streams so replies start quickly, and the emotion tag gives your animators the same signal EVI's tone gave the voice.

If you used EVI 4-mini for languages other than English, set the Language and Accent nodes per character and test each language in the browser before you switch the build.

Some things get better for the game itself. Characters can open doors, hand over items or start a quest beat through actions. They notice the objects and events your game reports. Microphone input works in Unity WebGL builds, so browser versions of your game can talk too.

If your project is bigger than one character

Larger EVI projects usually need a few extras:

• Scenes with several speakers. Up to six characters can share one conversation over the API on Pro and Team.
• Scripted story beats. Conversation Flows let a character move through branching beats and report checkpoint keywords (flowState) to your game.
• A team. The Team plan includes 5 seats, 20 custom voices and the quiz engine.
• Commercial release. Commercial use needs the Pro or Team plan.

If you are moving a larger project, or want help planning the switch, contact us.

Your next steps

1. Export your Hume prompts, configs and audio this week.
2. Start your migration with the character players talk to most.
3. Rebuild it in the editor and test it in the browser.
4. Swap your client for the Neocortex SDK in one build, and ship that before the November 13 cut-off.

After that date, your EVI integration stops answering and your Hume data is gone. Moving one character now leaves the rest as routine work in Neocortex.

Hume details are from Hume's documentation, checked October 2026.

Frequently Asked Questions