> ## Documentation Index
> Fetch the complete documentation index at: https://docs.thinnest.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Audio Ambience

> Add a low-volume background sound and a thinking-state filler clip to mask silence and LLM latency on voice calls.

# Audio Ambience

Two perceived-latency hacks borrowed from production voice agents:

* **Background sound** — a low-volume office-chatter loop running for
  the entire call. Masks silence, makes the agent feel "present in a
  room" rather than floating in a vacuum.
* **Thinking sound** — a short keyboard-typing clip that plays while
  the agent is in its "thinking" state. Masks LLM time-to-first-token
  and the gaps that open up during tool calls / agent handoffs.

Both are powered by LiveKit's `BackgroundAudioPlayer` under the hood.
The agent's TTS / Gemini Live audio plays on top — the ambience is
mixed at low volume so it doesn't compete with the spoken reply.

## Where to find it

In **Agent Studio → Voice Configuration → Advanced → Call Control**,
toggle the **Audio Ambience** card on. Click the gear icon to open the
configuration modal — every setting lives there.

## Configuration

### Background Sound

| Option                        | Behaviour                                                                |
| ----------------------------- | ------------------------------------------------------------------------ |
| **Off**                       | No background sound.                                                     |
| **Office Chatter** (built-in) | Subtle call-centre chatter loop. Plays continuously throughout the call. |
| **Custom**                    | Upload your own `.mp3` or `.wav` (up to 25 MB).                          |

A volume slider (0–100%, default **30%**) sits below the picker.

### Thinking Sound

| Option                         | Behaviour                                                                    |
| ------------------------------ | ---------------------------------------------------------------------------- |
| **Off**                        | No thinking sound.                                                           |
| **Keyboard Typing** (built-in) | Plays while the agent is in its "thinking" state — i.e. waiting for the LLM. |
| **Custom**                     | Upload your own `.mp3` or `.wav` (up to 25 MB).                              |

Volume slider (0–100%, default **50%**).

The thinking sound is auto-triggered by LiveKit's session events; you
don't have to wire anything to make it play during tool calls or
handoffs.

### Custom audio uploads

Click **Custom** for either slot to enable the upload zone. Drag a
`.mp3` or `.wav` in (or click to pick from disk). The file is uploaded
to the same audio asset endpoint used by the rest of the platform and
the URL is stored on the agent config.

You can preview the uploaded clip with the play button before saving.
Use the trash icon to remove the uploaded file.

<Note>
  Best tested on a real phone call. In a browser test (laptop speakers +
  mic, no echo cancellation), the agent can hear its own ambience and
  treat it as user speech. Use headphones, or test from a phone.
</Note>

## How it interacts with the audio path

* The ambience and thinking clips are published on the **agent's
  outbound audio track**. They don't go through the noise-cancellation
  path (NC only processes inbound caller audio).
* The mixer waits \~3 seconds after the session starts before the
  background streams attach, so the greeting TTS has time to drive
  the audio path. Without that delay, LiveKit's audio mixer drops the
  background streams on first-frame timeout.
* When the call ends, the player is closed cleanly and any
  temp-downloaded custom audio files are deleted.

## Cost

Audio Ambience is **free** — there's no per-minute charge.

## Quick start

1. Open your agent in **Agent Studio → Voice Configuration**.
2. Go to **Advanced → Call Control**.
3. Toggle **Audio Ambience** on. Both default to the built-in clips
   (office chatter + keyboard typing).
4. Click the gear icon if you want to upload your own clips, change
   volumes, or pick "Off" for either slot.
5. Save and test on a real phone (or with headphones).

## Next Steps

* [Noise Cancellation](/docs/voice/noise-cancellation) — clean up inbound caller audio.
* [Voice Configuration](/docs/voice/voice-configuration) — provider, voice, interruption settings.