Articles, Blog

The physics of playing guitar – Oscar Fernando Perez

October 21, 2019


Hendrix, Cobain and Page. They can all shred, but how exactly do the iconic
contraptions in their hands produce notes, rhythm, melody and music. When you pluck a guitar string, you create
a vibration called a standing wave. Some points on the string, called nodes,
don’t move at all, while other points, anti-nodes,
oscillate back and forth. The vibration translates through the neck
and bridge to the guitar’s body, where the thin and flexible wood vibrates, jostling the surrounding air molecules
together and apart. These sequential compressions
create sound waves, and the ones inside the guitar
mostly escape through the hole. They eventually propagate to your ear, which translates them into
electrical impulses that your brain interprets as sound. The pitch of that sound depends on
the frequency of the compressions. A quickly vibrating string will cause
a lot of compressions close together, making a high-pitched sound, and a slow vibration
produces a low-pitched sound. Four things affect the frequency
of a vibrating string: the length, the tension,
the density and the thickness. Typical guitar strings
are all the same length, and have similar tension,
but vary in thickness and density. Thicker strings vibrate more slowly,
producing lower notes. Each time you pluck a string, you actually create
several standing waves. There’s the first fundamental wave,
which determines the pitch of the note, but there are also waves
called overtones, whose frequencies
are multiples of the first one. All these standing waves combine
to form a complex wave with a rich sound. Changing the way you pluck the string
affects which overtones you get. If you pluck it near the middle, you get mainly the fundamental
and the odd multiple overtones, which have anti-nodes
in the middle of the string. If you pluck it near the bridge,
you get mainly even multiple overtones and a twangier sound. The familiar Western scale is based on
the overtone series of a vibrating string. When we hear one note played with another
that has exactly twice its frequency, its first overtone, they sound so harmonious
that we assign them the same letter, and define the difference between them
as an octave. The rest of the scale
is squeezed into that octave divided into twelve half steps whose frequency is each 2^(1/12)
higher than the one before. That factor determines the fret spacing. Each fret divides the string’s
remaining length by 2^(1/12), making the frequencies
increase by half steps. Fretless instruments, like violins, make it easier to produce the infinite
frequencies between each note, but add to the challenge
of playing intune. The number of strings and their tuning are custom tailored
to the chords we like to play and the physiology of our hands. Guitar shapes and materials can also vary, and both change the nature
and sound of the vibrations. Playing two or more
strings at the same time allows you to create new wave patterns
like chords and other sound effects. For example, when you play two notes
whose frequencies are close together, they add together to create a sound wave
whose amplitude rises and falls, producing a throbbing effect,
which guitarists call the beats. And electric guitars give you
even more to play with. The vibrations still start in the strings, but then they’re translated
into electrical signals by pickups and transmitted to speakers
that create the sound waves. Between the pickups and speakers, it’s possible to process
the wave in various ways, to create effects like distortion,
overdrive, wah-wah, delay and flanger. And lest you think that the physics
of music is only useful for entertainment, consider this. Some physicists think that everything
in the universe is created by the harmonic series
of very tiny, very tense strings. So might our entire reality be the extended solo
of some cosmic Jimi Hendrix? Clearly, there’s a lot more to strings
than meets the ear.

100 Comments

  • Reply CH1PSET August 14, 2015 at 12:49 am

    Better list: Hendrix, Rhodes, Petrucci

  • Reply JGui August 14, 2015 at 1:02 am

    mind fuck video.

  • Reply BrillionRadio August 14, 2015 at 3:46 am

    Great video to be sure! However, to lump in Kurt Cobain with Hendrix and Page is a tad disgusting 🙁 lol

  • Reply ace0swan August 14, 2015 at 4:19 am

    You went deep Ted-Ed, you went deep…

  • Reply MGMX August 14, 2015 at 6:22 am

    If you really want a guitar god, search for Mike Oldfield, John Petrucci or Tolgahan Çoğulu.

  • Reply Peleg Tsadok August 14, 2015 at 9:10 am

    Listing Cobain along with Hendrix and Page is like listing Justin Bieber along with Nina Simone.

  • Reply Ellena August 14, 2015 at 9:27 am

    Wow, Chris Boyle did an awesome job with this animation.

  • Reply Pratik Baral August 14, 2015 at 12:01 pm

    wow! a Cosmic Hendrix..sounds promising

  • Reply Adithya Lk August 14, 2015 at 12:03 pm

    Cobain can't shred.

  • Reply göldenshrouds August 14, 2015 at 12:56 pm

    So this is what getting high looks like.

  • Reply Lionelson Norbert August 14, 2015 at 2:22 pm

    which makes me wonder how did the first people made guitars? were they like "hey i'm just gonna put these stringstogether on this hollow tubes. then i'm gonna put frets on them just like so. whoa! it just made music!!"

  • Reply Daytonationz August 14, 2015 at 2:46 pm

    dat funky lesson

  • Reply Ashley Reinhardt August 14, 2015 at 4:34 pm

    jesus, how long does it takes to animate this video? ..

  • Reply Phoebe Wiseman August 14, 2015 at 4:46 pm

    that was the best TED ed I've seen so far 😀

  • Reply Sam H August 14, 2015 at 5:04 pm

    oh my this is such a dope video

  • Reply Jérôme Champigny August 14, 2015 at 5:43 pm

    That one is really outstanding.

  • Reply Esa Bani August 14, 2015 at 5:56 pm

    trippy ted-ed

  • Reply Juan Guevara August 14, 2015 at 6:17 pm

    Awesome animation! And music yoo

  • Reply Juan Guevara August 14, 2015 at 6:17 pm

    Awesome animation! And music too

  • Reply Eric August 14, 2015 at 6:42 pm

    I love me some cobain but he was a pretty shit guitar player

  • Reply Søren Nielsen August 14, 2015 at 8:15 pm

    Turn that background music down a notch or two

  • Reply Egor Gorshenin August 15, 2015 at 9:30 am

    Super strings

  • Reply Banana Bob August 15, 2015 at 10:32 pm

    Somehow takes the magic out the music

  • Reply Anand Krish August 16, 2015 at 4:17 am

    Amazing animation! (y) Great job!

  • Reply Nifty Fingers August 16, 2015 at 5:47 am

    I would change the description from "Oscar Fernando Perez details", to "Oscar Fernando Perez gives a general overview of".

  • Reply Espen Mons August 16, 2015 at 4:51 pm

    Simply the most awesome animation for Ted-Ed! 😀

  • Reply SuperDawgEater August 16, 2015 at 7:05 pm

    What is Cobain Shred?

  • Reply WisdomTooth August 17, 2015 at 1:53 am

    Tune instruments to 432 hz if you really want to feel the sound.

  • Reply Bonar Tirtananda August 17, 2015 at 9:05 am

    What's the background music called please, title or genre?

  • Reply Gregorio Salucci August 17, 2015 at 8:03 pm

    Espectacular

  • Reply Eduardo Dominguez August 18, 2015 at 3:33 am

    I dont know why.. but I never get music theory.. the moment people say half-step, octave or w/e my mind goes off and I get no information at all.

  • Reply omar lopez August 20, 2015 at 4:54 pm

    The music distracts me, I can't pay attention to the explanation

  • Reply Noodlepony August 21, 2015 at 7:31 am

    This is sooo trippy!!

  • Reply adrian kucinski August 23, 2015 at 9:01 am

    The idea of sound being related to String Theory seems obvious if you have a little knowledge of both.
    But the mention of "overtones" or upper partials could have been expanded a bit as it defines the characteristic sound of an instrument, and used together such as in a synphonic orchestra creates a very rich phonic experience.

  • Reply GuitarGod Joe August 24, 2015 at 6:22 am

    Damn! I thought I was having an acid flashback there for a moment. Cool vid indeed.

  • Reply Ben491514 August 25, 2015 at 1:22 am

    This is the best episode yet, i.m.o..  I agree with others on Cobain though, good writer, not as good in skill.

  • Reply Juanfra Vega August 31, 2015 at 3:40 pm

    Cobain?hahaa

  • Reply Daniel Björkman September 2, 2015 at 8:39 pm

    Sorry but thats not the first overtone at 1:50. You only imaged the progression of the standing wave

  • Reply RICHARD DAMROW September 7, 2015 at 1:02 pm

    Physics 101: you nailed the musicology subject well, but, in addition, you also tempted us to think beyond into the comic implications of good vibrations.

  • Reply TheMighty Chabunga September 11, 2015 at 10:32 pm

    Eh,.. Good info but BS advise.

  • Reply José Carlos Lazarte Aspíllaga September 14, 2015 at 2:08 am

    I loved the animation and music, so much indeed that I could barely pay attention to the explanation, but a couple things I will remember.

  • Reply ashnaa rabbani September 15, 2015 at 9:08 pm

    none of them are shredders but i love the ending

  • Reply The Commenter October 13, 2015 at 12:53 am

    Perfect video, rich details, information, art and rock : D

  • Reply Banda Safados Ateus November 8, 2015 at 12:08 pm

    This video is a work of art. Truly! Stunning animation matched perfectly with the great soundtrack and the explanation at the same time.

    It might be the best YouTube video ever!

  • Reply Marc Elpedes November 30, 2015 at 12:12 pm

    Cobain can shred? What?

  • Reply Alejozul December 11, 2015 at 4:07 pm

    Cobain?

  • Reply cande francia January 13, 2016 at 3:53 am

    the animation and background music were so distracting it was difficult to focus on the explanation!

  • Reply s ewind February 2, 2016 at 9:20 pm

    Fantastic production. Very useful indeed.

  • Reply Andréz CS2D March 16, 2016 at 5:28 pm

    best animations

  • Reply John Collins March 18, 2016 at 4:43 am

    Excellent!

  • Reply Lucien Khalil March 28, 2016 at 8:58 pm

    Knopfler > Cobain

  • Reply Duan Steven March 30, 2016 at 2:55 am

    wow cool!

  • Reply Ykeir April 7, 2016 at 6:19 am

    a bounch of reations and principle amongst electrons and stuff->cosmic engineer—> so called god

  • Reply Mochimilf April 9, 2016 at 2:06 am

    makes me want to listen to some tame impala now :')))

  • Reply MrHardrocker April 10, 2016 at 3:13 pm

    Shredders are guys like Paul Gilbert, Yngwie Malmsteen and Steve Vai.
    Please, TED, get your facts straight!

  • Reply John White April 15, 2016 at 8:07 pm

    Astonishing animation

  • Reply B-rice Alkaline May 28, 2016 at 3:43 pm

    Need to take a moment to appreciate how concise, and educating this video is

  • Reply Rob Grover June 7, 2016 at 10:39 pm

    Tolkien was right.

  • Reply Camo-ninja June 22, 2016 at 8:26 pm

    Alot of guitar snobs in the comments, don't you guys understand that playing it is an art. Theres no rules, you just express yourself. Some people like Cobain, and so what?

  • Reply Ben Kelly June 29, 2016 at 9:49 pm

    Kobain was shit at guitar

  • Reply Сделай это дома July 31, 2016 at 10:10 pm

    Hmm.. Had no idea Cobain could shred

  • Reply Jackson Elmore October 7, 2016 at 5:16 pm

    Do the physics of spitting over a beat

  • Reply Somekind of Dude October 8, 2016 at 12:28 pm

    how exactly Cobain can Shred?

  • Reply Daniel Rodriguez October 9, 2016 at 7:07 am

    Cobain and shred should not be in the same sentence

  • Reply Morenotedebotemalotecipote October 9, 2016 at 2:41 pm

    But can Cobain Djent ?

  • Reply virtualnuke 3553 October 9, 2016 at 5:51 pm

    So basically, Hendrix went on an acid trip and was able to shred after?

  • Reply HeShreds October 10, 2016 at 2:04 am

    Kurt Cobain put on the same level as Jimmy Page and Hendrix? I like Nirvana and all but … man, he's no where close to as talented as those other two.

  • Reply Alexx Jaxx October 10, 2016 at 8:43 am

    The music volume is to loud than the guy speaking about the topic.

  • Reply Adrian Larsen October 10, 2016 at 11:37 am

    Cobain =/= Shred

  • Reply Rory Horgan October 12, 2016 at 8:14 pm

    I'm sober and I thought this video was trippy AF

  • Reply Cool People Club October 20, 2016 at 3:41 pm

    Most of the comments seems to be pointing out that Cobain shouldn't be beside Hendrix and Page while the video itself was really well put together and an interesting experience when it comes to knowledge about string instruments and overall a better put together video than most of what you see in schools but in this case free, but that's none of my business.

  • Reply JaMaZz Jackson October 21, 2016 at 7:21 pm

    what the shred guys… to me the only obvious flaw here is it could be much longer 🙂 great video!
    (maybe he meant wood or paper or sth, for science's sake…)

  • Reply Raymond Duran November 24, 2016 at 4:38 am

    Kobain should be replaced by Stevie Vai or Brian May

  • Reply Siddhi Raskar January 8, 2017 at 5:48 pm

    aren't u just awesome like an angel ….. love it

  • Reply Flash93933 February 25, 2017 at 8:11 pm

    Clicks on video all excited to see the science behind guitars

    Leaves after watch the first 11 seconds

  • Reply Zack G. March 20, 2017 at 1:48 am

    since when is Kurt Cobain good at guitar

  • Reply King of heroes Gilgamesh April 25, 2017 at 6:18 pm

    cosmic jimi Hendricks! cool

  • Reply Ushnish De July 7, 2017 at 1:41 am

    Nice video, I just wish the music wasn’t playing throughout the entire video cuz it was kinda distracting

  • Reply Azolio Eroach November 4, 2017 at 6:14 pm

    So… Don't try to BE God, just do your best to join in on the JAM!?!?!?!!!! Cosmic theology! But… Why do all waves need strings?

  • Reply ShayaanR 87 November 28, 2017 at 7:11 pm

    s

  • Reply Camille Rynd January 18, 2018 at 5:21 pm

    you know while he is talking it kinda sounds like he is singing cause of the background music

  • Reply fahim shahriar ahmed February 26, 2018 at 7:04 pm

    This video just made me happy.

  • Reply Beloo Taku March 11, 2018 at 11:08 am

    The animation was awesome

  • Reply Le SpoderMan April 4, 2018 at 6:52 am

    Wha wha

  • Reply Ben Ripka April 13, 2018 at 4:06 pm

    This video is off the hooook! I study electrical engineering and signal processing, and this is exactly why. Keep it up TED-ed!

  • Reply Sid Vicious April 24, 2018 at 3:00 am

    I just learn that cobain can shred…very educational

  • Reply Hey April 26, 2018 at 5:00 pm

    We're can i find the tabs?

  • Reply Amit Upadhyay June 3, 2018 at 6:07 pm

    Wow! Awesome graphics and animation !!!

  • Reply Drake Josh July 25, 2018 at 6:07 pm

    I watch all of your videos, and this one is especialy excellent

  • Reply Andy O September 7, 2018 at 10:48 pm

    🍎🎸🎇🎓
    〰 〰 〰〰 〰〰〰
    🐒🙈🙉🙊
    💔❤💓💕🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸🎸

  • Reply Secorona972 YT September 20, 2018 at 2:26 pm

    Legit got an ad featuring someone playing a guitar

  • Reply Expressionless October 20, 2018 at 3:45 pm

    Face the truth, Cobain doesn't shred.

  • Reply Krislyn Placide October 24, 2018 at 2:33 am

    Cosmic Hendrix= God.

  • Reply The Big Flying Ninja December 6, 2018 at 6:15 am

    Yesss
    Love vids like this please continue to do more.

  • Reply Geethanjali Nagiri December 10, 2018 at 2:19 pm

    Ten Guitarists You Could've Named Instead of Cobain: A List
    -Slash
    -Eddie Van Halen
    -Eric Clapton
    -Keith Richards
    -Angus Young
    -Mick Mars
    -Randy Rhoads
    -Dimebag Darrell
    -Jeff Beck
    -Stevie Ray Vaughn

    P.S. Props for putting Hendrix and Jimmy Page (my personal favourite) on there, mate.

  • Reply shemaiah brad calle dinamling January 13, 2019 at 9:29 am

    nice animation awful example i mean cobain seriously…..you could have named dimebag, rhandy roads, eddie van halen…. but no u mentioned cobain…..

  • Reply Rinko Iwasaki May 9, 2019 at 2:53 am

    do one about red panda!!!!!!!!!!!!!!!!!! pleeeeeeeeeeeaaaase!!!!!!!! :] ;]

  • Reply Yash Jain May 22, 2019 at 8:46 am

    This was amazing!

  • Reply Mayra Santana June 15, 2019 at 11:28 pm

    First Ted ed video that I need to watch one more time to understand at all

  • Reply Naruto Uzumaki August 26, 2019 at 12:59 am

    What is the use or the point of having the hole in the middle of acoustics guitars

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