Unsound ToneGen

Unsound ToneGen is an intuitive pitch generation tool. Use it to match a tone you are hearing, such as sound system feedback, and it will tell you the frequency. Slide your finger up and down to control the frequency, left and right to control the volume. It’s useful for vocal frequency ranges and up to 12 kHz with nothing but the iPhone speaker, or down to 30 Hz with an earbud or headphones.