Originally Posted by: schmangeSorry, yeah.
It's just short speak for standard tuning.
440Hz is usually printed on tuners as the point where the guitar is actually in tune.
Like when the VU meter is dead center, you get a green light and the needle is pointing at 440.
Don't have a clue why but that's what I've always called it.
From My understanding it's called "A 440Hz" and it's the amount of vibrations per second (I believe) that the lowest "A" note produces when in tune. The "A Octive" has twice as many vibrations (A 880Hz). They say if you have a Male/Female duet, the female will sing an octive higher than the male because of genetics, so they can both harmonize in tune.