# Dynamics Processor Unit Parameters Parameters for the Dynamics Processor unit. ## Topics ### Constants [`var kDynamicsProcessorParam_AttackTime: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_AttackTime) [`var kDynamicsProcessorParam_CompressionAmount: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_CompressionAmount) [`var kDynamicsProcessorParam_ExpansionRatio: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_ExpansionRatio) [`var kDynamicsProcessorParam_ExpansionThreshold: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_ExpansionThreshold) [`var kDynamicsProcessorParam_HeadRoom: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_HeadRoom) [`var kDynamicsProcessorParam_InputAmplitude: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_InputAmplitude) [`var kDynamicsProcessorParam_MasterGain: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_MasterGain) [`var kDynamicsProcessorParam_OutputAmplitude: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_OutputAmplitude) [`var kDynamicsProcessorParam_ReleaseTime: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_ReleaseTime) [`var kDynamicsProcessorParam_Threshold: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_Threshold) [`var kDynamicsProcessorParam_OverallGain: AudioUnitParameterID`](/documentation/AudioToolbox/kDynamicsProcessorParam_OverallGain) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)