---
title: gainMetaParameterDefinition
framework: phase
role: symbol
role_heading: Instance Property
path: phase/phasegeneratornodedefinition/gainmetaparameterdefinition
---

# gainMetaParameterDefinition

A meta parameter that dynamically changes the audio’s loudness.

## Declaration

```swift
var gainMetaParameterDefinition: PHASENumberMetaParameterDefinition? { get set }
```

## See Also

### Controlling Audio Playback

- [rate](phase/phasegeneratornodedefinition/rate.md)
- [rateMetaParameterDefinition](phase/phasegeneratornodedefinition/ratemetaparameterdefinition.md)