The physics of playing guitar

Are you also a fan of rock bands who dreams to play a guitar one day? Well, you’re going to have to invest hours to perfect this practice. The physics behind this may be complex, but it’s fun to ponder over.


How does the guitar produce sound?

Let’s start off at the very beginning.

We all know that in order to create a melody we have to pluck a guitar’s strings. So, once you do that it leads to a vibration called the standing wave. Present on these strings are two points- the nodes and the antinodes. The nodes refer to those stationary points on the string that don’t even when you pluck the string. However, antinodes are the ones that set off in a to and fro motion.

The vibration so created travels throughout the body of the guitar, which in turn causes the thin wood to vibrate. This sensation then puts the air molecules around it in such a frenzied motion that they keep bumping into one another while trying to make a way out of the crowd as well. This entire process creates sound waves.

As these sound waves reach the listener’s ear to convert into electrical impulses which get read a sound by the brain.

Low pitch vs High pitch sound

The rate at which the string vibrates renders these compressions as either a high pitched or a low pitched sound.

So, if a string vibrates quickly, then it creates a greater number of compressions in closer proximity on the sound wave. Such a formation results in a high pitched sound. Similarly, in contrast, slow vibrating strings will generate a low pitched sound.

Frequency of a vibrating string

There are four factors impacting the frequency- the length, tension, density and the thickness of the string. It’s usually the thickness and the density that differs in varying guitar strings.

A thick string takes more time to vibrate, thereby creating a low pitched sound.

What is an Octave?

Once you start plucking the strings, you actually create several standing waves. The combination of the fundamental wave and overtones creates the sound that we ultimately hear from the guitar.

A single note can be played on different frequencies. Playing a specific note and then playing another with twice its frequency creates a melodic overtone. Though both notes are labelled as the same letter, the difference between them is defined as an octave.

The fret spacing on a guitar is intentional so that with each half step the frequencies also increase. This uses the above-mentioned concept of the octaves to create a rich sound. This is why it’s easier to play in-tune on a guitar. A violin, for example, has no fret spacing. This can lead to the production of infinite frequencies between notes, which makes it hard to control the tuning.

What are Beats?

Playing the guitar is all about making combinations, so when you pluck two or more strings simultaneously, it creates more complex musical patterns due to the increasing overtones.

There’s another interaction when two notes with closer frequencies are played together whose resulting sound wave’s amplitude creates a throbbing effect call the Beats.

You can produce as many combinations as you want and that’s why playing the guitar will never be a boring task.

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