Calculate the rpm, depending on the engine sound.
Through the calculation frequency, the sound is analyzed to determine the revolutions of an engine.
It is necessary to indicate the characteristics of the engine prior to reading.
May not work on all engines. It works worst with engines with the exhaust sound very muted and mechanical noise engines (air cooled engines).
It is normal to show some value even if no motor function.
Keywords: rpm, acoustic tachometer, sound, tach, rpm gauge, revolution counter, rev counter, rc, fft, tachometer