Tone Generator is a precise frequency and sound generator for your phone. It plays test and reference signals: a single tone (sine wave, square, triangle or saw), a frequency sweep, white, pink or brown noise, beats, separate left and right channels, and up to four tones at once. Every sound is generated live on the device, from 20 to 20,000 Hz with an accuracy of 0.01 Hz. What it is for Free modes Plus edition The free modes work without limits.