Signal Generator by NBSNot available
Signal Generator is a simple app designed to turn any Android powered phone or tablet into an audio testing device. Signal Generator is very simple to use. Select from a sine wave, square wave, saw tooth wave or white noise. The app supports any frequency from 50Hz up to 20KHz with amplitude control. Signal Generator has been tested on many devices. Please note that devices vary in their ability to generate an audible tone for the lowest and highest frequencies.