This Frequency Generator app lets you generate a sine wave tone with a frequency between 1Hz and 22000Hz. It is simple accurate and very easy to use.
Adjust tone frequency using a slider or number pad and press the play button.

This sound generating app can be used in multiple use cases:
1. You can test your hearing. Human being is capable of hearing frequencies in
average range of 20Hz-20000Hz. This range is getting smaller by the age.
2. Testing your speakers for the high end (treble) and low end (bass) tones.
3. Cleaning water from your smartphone speaker. Since sound is making small
vibrations it can help shaking of unwanted water from your speakers.
4. Having fun and making experiments with sounds.