OpeNoise is a free real-time noise level meter app designed for Android devices. Developed by Arpa Piemonte, the app allows users to measure the A-weighted sound pressure level in real-time. OpeNoise provides minimum and maximum level, third octave and FFT analysis, and data saving in a text file. The app also features calibration functionality.

However, it is important to note that OpeNoise is not intended for professional use and may not guarantee accurate noise measurement. The app provides a comparison with a professional noise level meter in the measurement dynamic range, and extemporary measurements might not be correct. The utilization of the app requires adequate technical knowledge and skill.

OpeNoise is an open-source app that is available for free on the Google Play Store. The code is under the GNU v.2 license or later, and it can be found on GitHub. Users who are interested in the older version can download it from the Arpa Piemonte website.

Keywords: noise level meter, level, sound, noise, measure, measurement, dB, db, dBA, dB(A), decibel.