piano doctor meet your piano's sound Measures entire range of keys from A0 to C8 Provides stable readings using 131,072 point FFT Detects fundamental and harmonic frequencies Shows spectrums Runs on iPhones and iPads Available in Apple’s App Store at the link below https://apps.apple.com/us/app/piano-doctor/id6738971293 Main Window at a Glance Demonstration: Detecting A0 (27.5Hz) Self-generated A0 tone is used Harmonic gauge finds a peak at 27.5Hz Demonstration: Detecting A2 (110Hz) Self-generated A2 tone is usedBoth fundamental and harmonic gauges find a peak at 110Hz