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

Upgrade instructions

To upgrade an existing Config to EVI 3, set the evi_version field to "3". See the Update an existing Config section of this guide for steps.

Changes

1. Updated voice options

   Legacy voices from EVI 1 and 2 are not supported with EVI 3. See our Voice Configuration Guide for further details on voice support across versions.

   To upgrade, select a new voice option from Hume’s Voice Library or your Custom Voice.

   Want to continue using a legacy voice option with EVI 3? Use Voice Cloning to replicate it for use in EVI 3.

2. Voice selection is required

   EVI 3 Configs require a voice option to be specified explicitly. Unlike previous versions, there is no default voice option.

   To upgrade, make sure to specify a voice option in your Config if you haven’t already.

3. Assistant prosody scores are relocated

   In EVI 1 and 2, assistant_message objects included prosody scores. In EVI 3, prosody is delivered separately as an assistant_prosody message for lower latency.

   To upgrade, match assistant_prosody messages to assistant_message using the shared id.

   Assistant Message

   1
   // Assistant Message
   2
   {
   3
     "type": "assistant_message",
   4
     "id": "c90ab17c1b064aec99c753bc172e7a3c",
   5
     "message": {
   6
         "role": "assistant",
   7
         "content": "Hi! How are you today?"
   8
     },
   9
     "from_text": false
   10
   }

   Assistant Prosody Message

   1
   {
   2
     "type": "assistant_prosody",
   3
     "id": "c90ab17c1b064aec99c753bc172e7a3c",
   4
     "models": {
   5
       "prosody": {
   6
         "scores": {
   7
           "Admiration": 0.157,
   8
           "Adoration": 0.0899,
   9
           // ...etc.
   10
         }
   11
       }
   12
     }
   13
   }