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# sendLevelMetaParameterDefinition

A parameter that gradually updates the amount of audio signal that passes through to the output.

```
var sendLevelMetaParameterDefinition: PHASENumberMetaParameterDefinition? { get set }
```

## Discussion

Use this property to fade reverb effects into a spatial mixer’s output.

For example, to begin with no reverb and gradually enable it, start by silencing reverb by setting the [`lateReverb`](/documentation/PHASE/PHASESpatialCategory/lateReverb) entry’s [`sendLevel`](/documentation/PHASE/PHASESpatialPipelineEntry/sendLevel) to `0`. Begin the fade by calling [`fade(value:duration:)`](/documentation/PHASE/PHASENumberMetaParameter/fade(value:duration:)) on this property with an argument of `1`.

---

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