# activity The activity level of each instrument over time, as values from 0.0 to 1.0. ``` let activity: [InstrumentActivityResult.Instrument : [MusicUnderstandingSession.TimedValue]] ``` --- 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)