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

# gainMetaParameterDefinition

A template for a parameter that changes the mixer’s volume gradually over a period of time.

## Declaration

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

## Discussion

Discussion When the framework creates a mixer from a mixer definition, PHASE initializes the mixer’s gainMetaParameter to this property’s values.

## See Also

### Controlling Volume

- [gain](phase/phasemixerdefinition/gain.md)