> [...] play an "a" at 440 Hertz to tune up the orchestra I was curious why A? The most common reason that turned up in search was that every string instrument

> [...] play an "a" at 440 Hertz to tune up the orchestra I was curious why A? The most common reason that turned up in search was that every string instrument in an orchestra has an A string. That makes sense, since bowed string instruments need one hand for the bow and one hand to press the string to the fingerboard for any note that isn't being played on an open string. That doesn't fully explain it though because they also all have G and D strings. One explanation said that it is because A is the highest open string pitch they have in common. Higher pitches are easier to hear in a group.