The Physics of Playing a Guitar Visualized: Metallica’s “Nothing Else Matters” Seen from the Inside of a Guitar

Give it a chance, you won’t be dis­ap­point­ed. While the first 30 sec­onds of the video above may resem­ble an ama­teur iPhone prank, it soon becomes some­thing unex­pect­ed­ly enchanting—a visu­al­iza­tion of the physics of music in real-time. The Youtu­ber places his phone inside an acoustic gui­tar, then plays Metallica’s “Noth­ing Else Mat­ters” against a back­drop of clouds and blue sky. Due to what Twist­ed Sifter iden­ti­fies as the phone camera’s rolling shut­ter effect, the actu­al waves of the vibrat­ing gui­tar strings are as clear­ly vis­i­ble as if they were on an oscil­lo­scope.

The com­par­i­son is an apt one, since we might use exact­ly such a device to mea­sure and visu­al­ize the acoustic prop­er­ties of stringed instru­ments. “A gui­tar string”—writes physi­cist and musi­cian Sam Hokin in his short explanation—is a com­mon exam­ple of a string fixed at both ends which is elas­tic and can vibrate.

The vibra­tions of such a string are called stand­ing waves, and they sat­is­fy the rela­tion­ship between wave­length and fre­quen­cy that comes from the def­i­n­i­tion of waves.”

Those with a physics back­ground might appre­ci­ate The Physics Class­room’s tech­ni­cal descrip­tion of gui­tar string vibra­tion, with sev­er­al tech­ni­cal dia­grams. For oth­ers, the video above by Youtube physics teacher Doc Shus­ter may be a bet­ter for­mat. Shus­ter explains such enti­ties as nodes and antin­odes (you’ll have to tell me if you get any of his jokes). And at about 2:25, he digress­es from his mus­ings on these phe­nom­e­na to talk about gui­tar strings specif­i­cal­ly, which “make one note for a giv­en tight­ness of the string, a giv­en weight of the string, and a giv­en length of the string.”

This is, of course, why chang­ing the length of the string by press­ing down on it changes the note the string pro­duces, and it applies to all stringed instru­ments and the piano. Oth­er fac­tors, says Shus­ter, like the body of the gui­tar, use of pick­ups, etc., have a much small­er effect on the fre­quen­cy of a gui­tar string than tight­ness, weight, and length. We see how the com­plex­i­ty of dif­fer­ent stand­ing wave forms relates to har­mon­ics (or over­tones). And when we return to the Metal­li­ca video at the top, we’ll have a bet­ter under­stand­ing of how the strings vibrate dif­fer­ent­ly as they pro­duce dif­fer­ent fre­quen­cies at dif­fer­ent har­mon­ics.

Shuster’s video quick­ly laps­es into cal­cu­lus, and you may or may not be lost by his expla­na­tions. The Physics Class­room has some excel­lent, free tuto­ri­als on var­i­ous types of waves, pitch fre­quen­cy, vibra­tion, and res­o­nance. Per­haps all we need to keep in mind to under­stand the very basics of the sci­ence is this, from their intro­duc­tion: “As a gui­tar string vibrates, it sets sur­round­ing air mol­e­cules into vibra­tional motion. The fre­quen­cy at which these air mol­e­cules vibrate is equal to the fre­quen­cy of vibra­tion of the gui­tar string.” The action of the string pro­duces an equal and oppo­site reac­tion in the air, which then cre­ates “a pres­sure wave which trav­els out­ward from its source.” The pres­sure waves strike our eardrums, our brains inter­pret sound, and there you have it.

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Note: An ear­li­er ver­sion of this post appeared on our site in 2015.

Relat­ed Con­tent:

Metal­li­ca Plays Antarc­ti­ca, Set­ting a World Record as the First Band to Play All 7 Con­ti­nents: Watch the Full Con­cert Online

Jazz Drum­mer Lar­nell Lewis Hears Metallica’s “Enter Sand­man” for the Very First Time, Then Plays It Near-Per­fect­ly

Watch Metal­li­ca Play “Enter Sand­man” Before a Crowd of 1.6 Mil­lion in Moscow, Dur­ing the Final Days of the Sovi­et Union (1991)

Free Online Physics Cours­es

Josh Jones is a writer and musi­cian based in Durham, NC. Fol­low him at @jdmagness

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Comments (5)
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  • Curtis says:

    What you are see­ing here is not the actu­al string motion, but am arti­fact of the video recorder.…

  • Robert Walker says:

    Very interesting.Next time try tun­ing the gui­tar first

  • Eyan says:

    Well the effect is from video arti­facts. The strings don’t move in a wave like that, the whole string moves back and forth. The rolling shut­ter cap­tures the strings in the mid­dle of this motion, so when the shut­ter moves down the string, it has already oscil­lat­ed to the oth­er side. And anoth­er cor­rec­tion, the string does­n’t direct­ly vibrate the air (well, not much. Would be about as loud as an elec­tric gui­tar not plugged into any­thing). The major­i­ty of the sound is from the pres­sure waves sent to the bridge, which vibrate the body. The body vibrat­ing echoes through the whole instru­ment and the sound exits main­ly through the sound hole, which then goes through the air to your ears.

  • Collin says:

    I noticed this effect about 35 years ago while play­ing gui­tar in front of my par­ents CRT tele­vi­sion. Hold and play the gui­tar so that you see the strings with the tv screen in the back­ground, and you will see sine waves rel­a­tive to the pitch/vibrating length of the strings.

    I lat­er worked as a gui­tar tech until fin­ish­ing school.

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