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# AudioUnitParameterValue

The data type for an audio unit parameter value.

```
typealias AudioUnitParameterValue = Float32
```

## Discussion

An audio unit parameter is an adjustable setting, such as gain. The parameters for Apple-supplied audio units are described in `Audio Unit Parameters`.

You can change a parameter value directly by calling the [`AudioUnitSetParameter(_:_:_:_:_:_:)`](/documentation/AudioToolbox/AudioUnitSetParameter(_:_:_:_:_:_:)) function, or schedule a change by calling [`AudioUnitScheduleParameters(_:_:_:)`](/documentation/AudioToolbox/AudioUnitScheduleParameters(_:_:_:)). See also [`AudioUnitParameterID`](/documentation/AudioToolbox/AudioUnitParameterID), [`AudioUnitParameter`](/documentation/AudioToolbox/AudioUnitParameter).

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