The law of twelve averages is a common legal system in the world. It was first produced by Zhu Zaiyu in China by mathematical calculation. The calculation method is to continuously find the root of 12 and get the frequency ratio of each semitone. Because the vibration ratio between semitones is equal, the average law of 12 is also called equal ratio. The power of 12 of root number 2 is equal to 1.0599. If the radix is 1, multiply it by 1 ... to 12 times in a row, and it will naturally return to octave. Look at the calculated frequencies: a220, #a233.08, b246.94, c 1 is 2665438+. D 1 is 293.66, #d 1 is 31.13, E 1 is 329.63, and f 1 is 349.23.