EVI Version

EVI 3 is the latest version of Hume’s Empathic Voice Interface. EVI versions 1 and 2 remain supported while developers transition.

This guide explains how to specify which EVI version is used in Chat and highlights the differences between each version, including capabilities, voice options, and pricing.

Version comparison

Set the EVI version

The EVI version is set using the evi_version field in your Config. The version associated with the config_id you provide when starting a Chat determines which EVI version is used.

To select a version when creating a Config:

1. Go to the Configurations page.
2. Click Create config.
3. In the first step of the flow, choose your desired EVI version.

Update an existing Config

To change the version of an existing Config:

1. Go to the Configurations page.
2. Find your Config by name and click Edit.
3. Select a different version from the edit page.

You can also update the version directly in the EVI playground by selecting a Config and changing the version in the panel on the right.

Migrating to EVI 3

This section details the changes required to migrate from EVI 1 or 2 to EVI 3, including Config updates, SDK upgrades, and client-side message handling.

Upgrade instructions

To upgrade to EVI 3:

• Set the evi_version field in your Config to "3".
• Follow the steps in Update an existing Config to apply the change.

SDK compatibility

The following SDK versions are fully compatible with EVI 3. If you’re using an older version, upgrade using the commands below.

React SDK (v0.2.1)

1
npm i @humeai/voice-react@0.2.1

TypeScript SDK (v0.12.1)

1
npm install hume@0.12.1

Python SDK (v0.10.1)

1
uv add hume==0.10.1

Breaking changes

1. EVI 3 introduces a new voice system

   • Impact: Voice options from EVI 1 and 2 are not compatible with EVI 3.

   • Reason: EVI 3 is powered by a speech-language model that supports an expanded, high-quality set of voices.

   • Action: Use a voice from the Voice Library or your Custom voices.

2. Voice selection is now required

   • Impact: Configs that do not specify a voice must now include one.

   • Reason: There is no default voice for EVI 3.

   • Action: If your Config does not already specify a voice, update it to include one from the supported options.

3. Assistant prosody is delivered separately

   • Impact: Prosody scores are no longer included in assistant_message payloads.

   • Reason: In EVI 3, prosody scores are sent asynchronously in a separate assistant_prosody message. This allows for lower latency during speech synthesis.

   • Action: Use the shared id field to associate each assistant_prosody message with its corresponding assistant_message.

   Assistant Message

   1
   {
   2
     "type": "assistant_message",
   3
     "id": "c90ab17c1b064aec99c753bc172e7a3c",
   4
     "message": {
   5
         "role": "assistant",
   6
         "content": "Hi! How are you today?"
   7
     },
   8
     "from_text": false
   9
   }

   Assistant Prosody Message

   1
   {
   2
     "type": "assistant_prosody",
   3
     "id": "c90ab17c1b064aec99c753bc172e7a3c",
   4
     "models": {
   5
       "prosody": {
   6
         "scores": {
   7
           "Admiration": 0.10722749680280685,
   8
           "Adoration": 0.06395940482616425,
   9
           // ...etc.
   10
         }
   11
       }
   12
     }
   13
   }

Summary