A free program for Android, by Tools Dev.

The Sound Meter is an app for measuring the noise level of any environment. It can measure the noise level in any place, such as the street, the office, or your house. It is designed to help you find out the level of noise in your environment, so you can decide whether it is safe to stay there or not.

The Sound Meter app uses the phone’s microphone to capture the noise level in your environment. It then calculates the decibel value and shows you how the decibel varies in different environments. 

The app is very easy to use and works on most Android phones. It is designed to be used in a quiet environment, so if you are in a noisy place, the app will not provide accurate data.