Decibel Meter: Sound level db is a free iPhone application developed for measuring noise levels in the surrounding environment. It offers features such as providing hints on when to protect oneself from excessive noise, working in the background for convenient measurements, determining peak values and calculating average noise levels, simple spectral noise analysis, and access to measurement history for further analysis. The app boasts a carefully designed user interface suitable for both beginners and professionals.

In addition to measuring noise levels, the app offers a subscription service, Decibel Meter Plus, providing access to all functions. Users can enjoy a free 3-day trial before opting for the monthly auto-renewing subscription. It's important to note that cancelling the app does not automatically cancel the subscription, and users are encouraged to review the Privacy Policy and Terms of Use before subscribing.