iOscilloscope (App Store link) is a new $.99 app that turns your iPhone into a virtual oscilloscope that can measure sound waves in real time.
iOscilloscope lets you do do several different things:
- FFT allows you to view the sound waves in Fast Fourier transform mode.
- Mute, mutes the sound so that there is no feedback.
- Sonogram allows you to view the sound waves in a sonogram form.
Note that iOscilloscope will not function when headphones are plugged into your iPhone.