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

# Noise Cancellation & Background Audio

> Clean up the caller's audio, and add thinking and ambient sounds to make calls feel natural.

<Frame>
  <img src="https://cdn.zeroruntime.ai/zrt/docs-resource/agent-builder/noise-background-audio.png" alt="Noise Cancellation with a model selector, and Background Audio with Thinking Sound and Ambient Sound toggles" />
</Frame>

## Noise Cancellation

Reduces background noise in the caller's audio for clearer recognition. Turn it on and choose a model from **Select model**, for example **AiCoustics - Quail VF 2.2 Small**.

Noise cancellation is set per language, and it works with both cascading and realtime pipelines.

## Background Audio

Expand **Background Audio** to add sound to the call.

| Setting | Plays | Options |
| - | - | - |
| **Thinking Sound** | Only while the agent is thinking, for example during an LLM response or a tool call. | Sound, volume (0–100%, default 10%), preview. |
| **Ambient Sound** | Throughout the call, for example soft office noise. | Sound, volume (0–100%, default 10%), preview. |

**Loop audio** (on by default) repeats the selected sounds when they reach the end.

<Tip>
  A subtle thinking sound fills the silence during slow tool calls, so callers don't think the line has dropped.
</Tip>


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