This is similar in principle to the funky little SOS Tuner from Planet Waves.
http://store.daddario.com/category/148531/S.O.S_Tuner
The LEDs strobe the strings at different rates and let you see the vibrations. Match up the strobes and you’re in tune. Works pretty well in a dark room, but takes practice and is too fussy to be really practical. A neat novelty, though.
I watched the demo. The two beams didn’t seem to stop so well and that was an animation. I’m guessing a person would have to hold the tuner in some manner so that the light could project onto the strings. That seems awkward.
It has a built-in pick, So you hold the whole thing exactly like a pick and pluck, and the strobes end up right over the string. But you’re right, it’s fussy.
That hits all the right spots on my Sweet!-o-meter.
Wait, that didn’t sound right…
Anyway, pretty nifty. I shall be trying that post-haste.
Harpists sometimes get crazy visual distortion (or problem focusing) depending on what’s “behind” or more correctly, on the right side of our harps. Weird curtain patterns or wall paper can be deadly, especially if you aren’t terribly sure of the tune and need to look through the strings more than usual.
One really interesting thing I found is that when you are practicing in front of the TV, when you pluck the B string of a harp, you can see the vibration in much the same way as you did on the youtube video. B works best, most of the other strings are not noticeable. I’m guessing it has something to do with the frequency.
American TV (NTSC) uses a frame rate of 60 interlaced (or 30 full) frames per second. Equal Tempered B is 61.7 Hz or multiples thereof. So the low beat rate of 1.7 Hz is probably what you’re seeing. Higher beat rates would be less noticeable. Interesting.
OK, Mr Smart Trousers, let’s see you find the
note that would give the same effect in PAL.
As I recall, PAL has a refresh rate of 50 Hz. An equal-temperament low G, at 49.0 Hz, should give you a nice one-cycle-per-second effect.
Science!