This application was developed by Real-Time Specialties, an audio
engineering company which develops, amongst other specialties,
piano-tuning software. The software is easy to set-up, requiring
only a microphone attachment for your laptop. You can use it to
verify the tach on your airplane (or car, or boat, or lawnmower).
It's exceptionally accurate, and it's not deceived by the number of
cylinders, gearboxes or mufflers! For PCs only - sorry no Mac
version at this time.