Tone Generator for iPhone
So you would like to experiment with sound frequencies on mobile devices? Tone Generator for iPhone has you covered. It generates pure sine wave tones at frequencies from 20hz to 22,000hz. It has two sliders to adjust the frequency and volume. You can transmit audio to any AirPlay supported device.
This app is great for tuning instruments, science experiments, and everything in between. You can find out more about it here.