Sound Tools 3 Free is a hobby sound pressure meter (SPL) for Android devices that comes with an analog VU meter and an oscilloscope. It is ideal for verifying sound levels and measuring loudspeaker response. However, it is important to note that this app is intended for fun and does not provide accurate measurement in decibels.

This app has a 30 to 102dB range, local peek/max values display, and response modes such as fast, medium, and slow. Additionally, it has an analog vu meter, digital vu meter, and an oscilloscope. The app also supports tablets and landscape mode, a chart, and sending the chart to email. Lastly, there is support for calibration.

Overall, Sound Tools 3 Free is a great app for hobbyists looking to measure sound levels and loudspeaker response. However, it is important to keep in mind that this app is intended for fun and should not be used for accurate measurement in decibels. Additionally, the app is 100% ad-free, making it a great choice for users looking for an uninterrupted experience.