# init(engine:sourceGroups:targetGroups:gain:attackTime:releaseTime:attackCurve:releaseCurve:) Creates an object that manages competing sounds. ``` init(engine: PHASEEngine, sourceGroups: Set, targetGroups: Set, gain: Double, attackTime: Double, releaseTime: Double, attackCurve: PHASECurveType, releaseCurve: PHASECurveType) ``` ## Parameters `engine` The app’s instance of the framework object. `sourceGroups` The sounds that determine volume reduction. `targetGroups` The sounds that reduce in volume. `gain` The volume level of the sound. `attackTime` The amount of time for sound reduction to reach maximum strength. `releaseTime` The amount of time to transition from maximum sound reduction to no reduction. `attackCurve` A mathematical curve that shapes transition progress during the time it takes to reach maximum sound reduction. `releaseCurve` A mathematical curve that shapes signal progress during the time it takes to transition from maximum sound reduction to no reduction. --- 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)