> For the complete documentation index, see [llms.txt](https://docs.acestudio.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.acestudio.ai/ai-instruments/create-instrument-sounds/expression-controls.md).

# Expression Controls

## What Are Expression Controls

Expression Controls are parameters you can automate over time to add nuance and realism, allowing you to "paint" where an effect should be active.

### Available Controls

<details>

<summary>Vibrato</summary>

Vibrato is a subtle and rapid fluctuation in a note's pitch, which adds warmth, expression, and richness to the sound.

</details>

<details>

<summary>Split-tones</summary>

Split-tones are an advanced technique that creates a rough, textured sound by producing multiple pitches simultaneously. It's perfect for adding a raw, edgy character or a sense of tension to your melody.

</details>

## Editing Expression Controls

<figure><img src="/files/wzW3Up6OMkJczIZwR5MF" alt=""><figcaption></figcaption></figure>

1. Select the Expression Control below the piano roll.
2. Click and drag to "paint" the regions to activate.
3. Simply right-click and drag over an active region to erase it.


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