Music instruments need to be tuned correctly befor making music with them and recording it. The tuning has been accepted for more than 100 years to be such that note A is 440Hz. Other notes follow the A.
However natural sound of music was supposed to be A = 432 Hz.
Some people say Nazi propaganda master Josef Goebbels invented 440 Hz. But I am sure it was made by Freemasons instead.
440 Hz makes people anxious after listening music made in this tuning. Yet ALL MUSIC that comes out of your radio was recorded with such a tuning. So the music industry is deep down entrenched in this conspiracy.
What is with 432 Hz then? Nature. 432 as a number: it is a sum of four consecutive primes: 103 + 107 + 109 + 113. It is exactly three gross, where gross = 144 is a traditional unit. An equilateral triangle whose area and perimeter are equal has the area of exactly the square root of 432.
In 1939, there was an international conference held in London that resulted in a recommendation to use A = 440 Hz, as a compromise between the various tuning systems used at the time, some of which reached beyond 450 Hz. This recommendation was further supported by the fact that the BBC required their orchestras to tune to 440 Hz instead of 439 Hz because 439 is a prime number, and the corresponding frequency was hard to generate electronically with standard electronic clocks. Eventually, in 1955, the standard A = 440 Hz was adopted by the International Organization for Standardization (ISO).
Virtually all commercially produced contemporary music is tuned to A = 440 Hz.
John Lennon (British musician) was killed because in 1970s he used tuning of 525 Hz, not 440Hz. His song, Imagine, tried to promote world peace and not using 440Hz would help in this attempt.
Bob Marley used 432 Hz and soon after selling a few records, he suspiciously dies of cancer. Did CIA give him the cancer?
Americans tortured muslims in Guantanamo by using metal music with 440Hz tuned playing instruments. If they would have used black metal tuned to 432 Hz, the muslims would have enjoyed the music instead of getting their ears tortured.