How guitars work

Now that we have already learned the different parts of the guitar, we move on to the next part which is understanding how those parts work together.

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String vibration and String Length

All musical instruments create sound by means of vibration. For wind instruments, the vibration derives from air passing over a mouthpiece, or from lips buzzing into a mouthpiece. For percussion instruments, the vibration comes from striking a surface made of canvas or metal. For string instruments, like guitars, the vibration comes from striking a string, which then vibrates. Of course, the strings would never vibrate if it were not given some sort of force or what we commonly know as tension. When a string is brought to a certain tension and then set in motion by a certain form of action like that of strumming or plucking, it produces a sound or a pitch. The different tones we hear from the strings of the guitar is simply achieved by tuning the strings to different tensions. The greater force or tension a string has, the higher the pitch it will produce.


To be able play music using a guitar, series of pitches or notes must be produced and we already know that this is achieved by drawing the strings to different tension. But, it wouldn't be that fun if you can only change pitches by adjusting the tension through the tuning keys everytime you pluck a string. Well, it could work if a guitar only has one string but we are talking about the six-string type of a guitar. What will happen if you need to play all of them at once in different pitches?

So, guitarists resorted to another way to change the guitar's pitch by fretting. Fretting the guitar is the act of placing or pushing your fingers against the fretboard in order to shorten the effective vibrating length of the strings. In this way, the vibration would only occur between the fingered fret and the bridge. By simply moving your left hand up and down the neck, you can change pitches comfortably and easily.

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You need to use both hands

In comparison to the piano where you can play the C-note by just pressing the white key above the it's brand logo, a guitar normally requires two hands working together to create music. One hand to do the fretting and the other to do the strumming or plucking. To play the C-note on the guitar, you must take your left-hand index finger and press down the 2nd string at the first fret. Now, doing that alone wouldn't produce a sound. You must then strike or pluck that 2nd string with your right hand to actually produce the C-note audibly.

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Intervals

In music theory, intervals are the formal way to describe pitch differences. They are universal across instruments and the music community. The smallest interval of the musical scale is the half step or what are commonly known as sharps and flats. On the guitar, the frets represent these half steps. You don't need to worry about that for know as we will be discussing half steps in detail soon.

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Sound production

So how do guitars produce a sound out of vibrating string?

Well, for an acoustic guitar, that’s no problem, because it has its own amplifier in the form of a hollow sound chamber or sound box that boosts its sound. But when you are using an electric guitar, the process works differently because it has no means of increasing the sound made by the vibrating strings. That's why you can only hear a tiny buzzing sound when you strum an electric guitar and that sound can't be heared even if you are just a couple of feet away.

To produce sound, an electric guitar, instead of using a sound chamber, senses the vibrations of the strings electronically and routes an electronic signal to an amplifier and speaker. It does so using the pickups mounted underneath its strings. These pickups are made of bar magnets wrapped with thousands of fine wire. So, when a string vibrates, it disturbs or modulates the magnetic field aroung the pickups. And when this happens, the pickups produces tiny electric currents that reflect the modulation. When you pass the electric current through an amplifier and then a speaker, you now hear a musical sound.

Before we end our lesson for today, let me remind you about a very important thing: a guitar makes the sound, but you make the music.