It is an application that estimates the engine Revolutions Per Minute [RPM] from the exhaust noise of a motorcycle or car when idling. By all means for maintenance of vehicles without tachometers such as scooters !

The idling sound includes the sound of the engine exploding, the rotation of the crankshaft / motor e.t.c., and the sound of various parts.
This application divides the sound measured by the microphone for each frequency and calculates the rotation speed [rpm] from the loudest frequency.
* Measurement results may vary due to various factors such as ambient sound, vehicle type, terminal used, and distance from the sound source. Please treat the measurement result as a reference value. In addition, it may not be possible to measure correctly depending on the model, rotation speed, and microphone performance.

• Set the number of engine strokes and cylinders
• Start measurement with “RUN” or “▷”
• Adjust the Gain and Threshold to place the peak value above the Threshold line
• Select any peak with "<" and ">"
• Stop at “□”
* Measurement will stop when the count is exhausted. You can extend the measurement time by seeing the reward advertisement or restart.

* Never use it while driving. There is a risk of accidents.
* Do not touch the heat source, keep away from it. There is a risk of burns or terminal failure.
* Securely fix the vehicle or machine so that it does not move. It may fall or move suddenly, leading to an unexpected accident.

For a long time, DIY has always liked to maintain motorcycles as a hobby.
When deciding the idling height while thinking "Is it like this?" When repairing an engine malfunction or carburetor in winter, or when adjusting the air screw, ask "Where is the number of revolutions high?" I was setting the settings while feeling. Then I had the opportunity to study the Fourier transform in another case, and if I analyze the engine sound with this, I think it can be quantified. What I thought was interesting was the reason I decided to do DIY.

I hope this app helps someone somewhere in the world.