A free program for Android, by TMSOFT.

This is a tone generator app that allows you to generate pure sine wave tones at frequencies from 20hz to 22,000hz. It can be used for various purposes such as hearing tests, tuning instruments, science experiments, and testing audio equipment. It has a wide range of use. It is perfect for musicians who need to tune their instruments and for guitar players who want to experiment with different string sounds. It can also be used for sound testing. This app is very useful for music and sound studies. You can use it for many purposes such as hearing tests, tuning instruments, science experiments, and audio system testing.