ConfigureVoice & language

Audio environment

Add a background sound and apply a voice filter to outbound agent audio.

Overview

Audio environment controls how the agent’s outbound audio sounds to the caller. Two settings apply:

  • Background sound plays a looping ambient sound under agent speech.
  • Voice filter applies a phone-style filter to the agent’s voice before that mix.

The caller hears the result. The agent does not hear the background sound, and it is not sent into speech recognition.

This is separate from tool call sounds, which play only while a tool runs.

Background sound

Background sound mixes a built-in preset under agent speech for the duration of the conversation. The sound keeps looping when the user interrupts; it does not stop with the agent’s turn.

Presets include office, restaurant, city, typing, and elevator music. In the dashboard, you can preview a preset before you save.

Configure background sound with conversation_config.conversation.background_sound.

Configuration

1

Open Audio environment

Open your agent. On the Agent page, next to Voices, click the Audio environment button.

2

Enable background sound

Turn on Enable background sound. Choose a preset from Background sound. Use the play control next to the dropdown to preview it.

3

Set volume and looping

Set Volume. Keep Crossfade loop enabled to avoid an audible click when the sound repeats. Save your changes.

On very poor WebSocket connections, mixing background sound can produce choppy audio.

Parameters

Valid source_id values are office1, office2, restaurant, city, typing, and elevator1 through elevator4.

FieldTypeDefaultDescription
source_typestringunsetMust be preset when a sound is enabled. Set together with source_id.
source_idstringunsetIdentifier for a built-in preset.
volumenumber0.15Level relative to agent speech. Range 0.01–1.0.
crossfade_loopbooleantrueCrossfade at the loop boundary so the sound does not click when it repeats.

Voice filter

Voice filter reshapes the agent’s generated voice. It does not equalize or denoise the background sound. The filter runs first; background sound is mixed under the filtered speech.

Voice filter is dashboard-only. It is not part of the public agent API or CLI schema, and it may not be available on all workspaces.

In the same Audio environment panel, set Voice filter to Off or a phone preset, then save.

Limitations

  • Built-in presets only. You cannot upload a custom file or point at an arbitrary URL.
  • Audio environment controls are hidden when the agent is text-only.
  • Background sound is not mixed into WhatsApp voice-message replies. WhatsApp calls still include it.
  • Background sound cannot be set per conversation through client overrides; conversation_config_override does not include background_sound. You can still change it on a workflow node.
Tool call sounds

Play ambient audio only while a tool is running.

Voice customization

Choose a voice, speed, and other speech settings for the agent.