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Guitar String Oscillations caught by iphone

  1. Jul 15, 2011 #1

    G01

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    Don't know if this have been posted here yet (anyway I don't see it on GD yet)



    Anyway, this is pretty cool, even if it isn't a true representation of the guitar strings' motion. The "rolling shutter" effect in the iphone's camera can be used to pick up representations of the sounds being produced by guitar strings. Each row of pixels in the camera records at a different time. Thus, different rows of pixels pick up the string at different points in it's motion.
     
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Jul 15, 2011 #2
    I was initially skeptical: it looks so little like the way a string moves. I did a rough on screen measurements when he is playing the strings in sequence (around 1:55) and the wavelength of the high E string is about one-quarter that of the low E (i.e., the bottom string in the shat vs the top string), as it should.

    These http://www.youtube.com/watch?v=17PSgsRlO9Q" gave me a fuller sense of what the rolling shutter does.

    It is not obvious to me how the images in the guitar video correspond to what the string is actually doing (simulated http://zonalandeducation.com/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.html" [Broken]).
     
    Last edited by a moderator: May 5, 2017
  4. Jul 15, 2011 #3

    dlgoff

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    I liked the finger picking the most. :smile:
     
  5. Jul 17, 2011 #4
    You can get the exact same effect with a light source and your eyes.

    I first noticed this in 1981 when I saw a guy in a music store slowly dive bomb the tremolo bar in front of an amp.

    I was standing close enough to see both the guitar and speaker and watched them synch up and feed back before seeing the effect of the strings as the feedback went up first one, and then two, octaves.

    At that time, I was playing through headphones connected to the cassette tape recorder by using the mic input and I wanted to do this at home but I was living at home (I was a kid).........so I invented a device that removed the speaker and air part of the feedback chain and kept it in the electromagnetic realm.

    This working model required nearly 50 watts to feed back but really wanted to feed back direct from transducer to pickup with such ferocity I needed to isolate the transducer from the pickup timewise by using a delay.

    I rushed off to the patent office and spent months going through patents until I ran into something similar which used a transducer that vibrated the headstock.

    I surmised that, if someone had invented something with similar functionality and it hadn't taken the guitar world by storm, then it just wasn't marketable........as Tom Scholz, and the guys at fernandes told me when I discussed the idea with them.

    This device later appeared as "the sustainer" marketed by fernandes and the "sustaniac" by maniac music (who evolved thier headshock shaker after fernandes introduced thier product).

    If you really want to see something cool, watch the strings of a guitar with a strobe light and hit some open string harmonics.
     
  6. Jul 17, 2011 #5
    That is pretty cool! I like this one from the 'suggested videos' in the sidebar:

    https://www.youtube.com/watch?v=ltMPMz37VPk&feature
     
    Last edited by a moderator: Sep 25, 2014
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