# Audio FX

> Put a voice in a room, a car or a church with a reverb, or add a telephone, megaphone or echo effect. A flat 20 credits per run, plus custom delay and EQ.

Source: https://nodaro.ai/docs/nodes/audio/audio-fx

The **Audio FX** node puts an effect on an audio clip. It adds a reverb that places a voice in a space, a telephone or megaphone sound, an echo, or a custom delay and EQ. Its main use is to place a dry voice in a scene. A clean [Text to Speech](https://nodaro.ai/docs/nodes/audio/text-to-speech) voice over a video can sound as if it was recorded somewhere else. A room reverb makes it sound recorded in that space.

- Found in: Audio › Edit Audio
- Output: audio
- API type: `audio-fx`

## When to use it
- Make a generated voiceover sound as if it was recorded in the room on screen.
- Make a line sound like a phone call or a public address announcement.
- Add an echo or a slap-back to a voice.
- Add an effect to a single stem from [Audio Separation](https://nodaro.ai/docs/nodes/audio/audio-separation).

## Quick start
### Add the node

Press Tab on the canvas and choose **Audio › Edit Audio › Audio FX**.

### Wire the audio

Wire an audio node into the **Audio** input: a generated voice, an upload or a separated stem.

### Choose the effect

Open the settings panel and choose an **Effect**. The default is **Room (indoor)**. For a reverb, set the **Wet / Dry mix**.

### Run it

Click **Run** on the node. The processed audio appears on the node with a player.

Workflow: A dry generated voice gets a room reverb, so it sounds recorded in the scene it is merged onto.

- Text to Speech → Audio FX (audio)
- Audio FX → Merge Video & Audio (audio)
- Generate Video → Merge Video & Audio (video)

## Input and output
| Input | Accepts | What it does |
| --- | --- | --- |
| **Audio** | Audio nodes, such as Text to Speech, Upload Audio and Audio Separation | The audio to process. |

The output, **Audio**, is the processed audio. It connects to any audio input, such as [Merge Video & Audio](https://nodaro.ai/docs/nodes/video/merge-video-audio), [Voice Changer](https://nodaro.ai/docs/nodes/audio/voice-changer) or [Mix Audio](https://nodaro.ai/docs/nodes/audio/mix-audio).

## Settings
| Setting | What it does |
| --- | --- |
| **Effect** | The effect to apply. The default is **Room (indoor)**. |
| **Wet / Dry mix** | Reverb effects only. From 0 to 100. Higher means more room and less direct voice. Each reverb has its own default. |
| **Delay (ms)** | Echo and Custom only. From 20 to 2,000. The default is 250. |
| **Decay** | Echo and Custom only. From 0.1 to 0.9. The default is 0.4. Higher gives more repeats. |
| **EQ Low (dB)** and **EQ High (dB)** | Custom only. From -20 to 20. The default is 0. |

## Every effect

**Reverb spaces** place the voice in a space:

| Effect | Space |
| --- | --- |
| **Room (indoor)** | An ordinary room. For dialogue. |
| **Bathroom** | Small, bright and tiled. |
| **Car interior** | A tight, damped cabin. |
| **Hall / Lobby** | A medium-sized room. |
| **Concert Hall** | A large space with a lush tail. |
| **Church** | A cathedral: long and dark. |
| **Cave** | Dark and diffuse. |
| **Arena / Stadium** | A huge space with a bright public address tail. |
| **Outdoor (open air)** | Almost dry, with faint reflections. |

**Character effects** change the sound itself:

| Effect | Sound |
| --- | --- |
| **Telephone** | A band-limited phone line. |
| **Megaphone / PA** | A mid-forward sound with some grit. |
| **Echo / Slap-back** | A distinct repeat of the sound. |
| **Custom** | Your own delay and EQ. |

## Credits
Audio FX costs a flat **20 credits per run**.

Reverb effects calibrate their level when the node runs. If the calibration cannot complete safely, the run fails and the credits are refunded: the node never renders a reverb at a guessed level. A passing failure succeeds on a retry. If the same run keeps failing with a calibration error, report it instead of retrying.

## Tips
- **Keep dialogue reverb light.** For dialogue indoors, **Room (indoor)** with a mix of about 25 to 35 is usually enough. Too much reverb makes speech muddy.
- **Match the reverb to the shot.** Use **Church** or **Cave** for big stone spaces, **Car interior** for car interiors and **Outdoor (open air)** for exteriors, kept subtle.
- **Apply effects before the merge.** Put Audio FX in front of [Merge Video & Audio](https://nodaro.ai/docs/nodes/video/merge-video-audio), so that the placed voice is what lands on the video.
- **Several voices at once.** [Voice Changer Pro](https://nodaro.ai/docs/nodes/audio/voice-changer-pro) has the same effects built in, applied to the new voices before the background music is mixed back.

## From the API
`POST /v1/audio-fx` takes `audioUrl` and the optional `preset`, `mix`, `delayMs`, `decay`, `eqLow` and `eqHigh`. The MCP tool is `apply_audio_fx`. See [Voice and media](https://nodaro.ai/docs/developers/api/voice-and-media).

## Frequently asked questions

### How do I make a voiceover sound as if it was recorded in the scene?

Wire the voice through Audio FX with the Room (indoor) effect and a Wet / Dry mix around 25 to 35. Then merge the result onto the video.

### Which effects does Audio FX have?

Nine reverb spaces, from Room and Bathroom to Church and Arena, plus Telephone, Megaphone / PA, Echo / Slap-back and a Custom mode with delay and EQ.

### How many credits does Audio FX cost?

A flat 20 credits per run. If a reverb cannot be calibrated safely, the run fails and the credits are refunded.

### Should I add the effect before or after merging the voice onto the video?

Before. Put Audio FX in front of Merge Video & Audio, so that the placed voice is what lands on the video.