[A=440Hz]

[A=442Hz]

Specifications: Pinch the handle of the tuning fork and lightly hit the tip to vibrate. As you vibrate, the tip of the handle closer to the side of the piano and other hard objects to the ear and hear sound.
Example: The sound of the A-tone fork is a sound A sound, so it is a sound of the A-line open-string, "la" that is used in many string instruments. Furthermore, the A sound of the tuning fork is 2 octaves higher than the 5-string open sound (A sound), so you need to match it with the harmonics of the 5-string and 5-fret. Although it is difficult to get used to it, tuning with tuning forks can also be used to train your ears and it is also a popular item for healing in recent years.
A = 440 was held in London in 1939 at an international conference in 1953 and it was still unchanged until (2019). (Usually marked "A=440 Hz" or "A440") However, there are many orchestra and brass bands that fit with a pitch of A=442 or above, especially the A=442 is standardized in the classic. 440 Hz sounds 3 times at the end of an 880 Hz (1 octave higher than 440 Hz) on TVs, radios, and 117.