We have our guitar, now understand all the parts of the guitar too, and so it will be a good idea to also develop some understanding on how it produces sound.
How does an Acoustic Guitar work?
It all starts with the string. When you pluck any string, it vibrates. Since it is resting on the saddle, the vibrations get transferred to it. From the saddle, they move to the bridge and finally to the sound plate. Yes! The entire sound plate starts vibrating when you pluck a string.
Try it and check for yourself.
Place any finger on the sound plate and pluck any string. You will be able to feel the vibrations easily.
Anyways back to the physics of how sound is produced.
The Acoustic guitar is a hollow device which essentially means that there is a whole lot of air inside the sound box/ body. The vibrating sound plate disturbs the air inside the box, leading to movement of the air inside the body. This air then travels around in the sound-box and comes out of the sound-hole producing sound. It’s that simple and fascinating.
What we just went through is pure physics of sound. I will get to the part on different sound produced due to changing strings, pressing on frets etc.
How does an Electric Guitar work?
Unlike an Acoustic Guitar, an Electric Guitar is a solid piece of wood. Hence, there is no air inside the body that vibrates due to movement of the strings.
Remember we discussed about these metal parts called Pickups in the previous article? Those are what produce the sound.
These metal pickups have coils of very fine wire (thiner than a human hair strand). These coils are generally between 7000 and 8000 in number. Due to these coils, the metal piece behaves like an electro-magnet, generating a magnetic field around the pickup.
What happens in an electric guitar is that the vibrations of the strings disturb the magnetic field which lead to production of a signal that is sent from the pickup to an external amplifier. This amplifier amplifies the signal in the form of sound and then you hear what you hear 🙂
How does sound get changed with different strings, frets?
Now that we have understood how sound gets produced, let’s dig a little deeper into the physics of sound.
Sound is a function of the frequency of vibrations of the string.
A loose string will vibrate slower than a tight string. And slow vibrations mean a deeper sound (bass) while fast vibrations mean sharper sound (treble). That should explain why the fat strings are so bass-y while the thin strings have so much treble in them. So that’s one way to get a different sound – by playing a different string depending on its thickness.
Which brings us to the tuning keys. They play a simple role to tighten or loosen the strings. I think you have understood what happens next.
Every time you tighten a string, the frequency of vibrations increases making it vibrate faster and so we get a sharper sound. The opposite is also true. You loosen the strings with the tuning keys and they vibrate slower producing a deeper sound. But this phenomenon is not used creatively while playing. As in, you don’t see guitarists changing the tuning, in the middle of a song to get a different sound (Nowadays some do actually but they’re a different breed).
Which brings us to the metal pieces on the fretboard called the frets. Remember, I told you they plan an important role in the previous article? Let’s get into that now.
If you press a string behind any fret, you will realise that, that particular fret now behaves like the nut. In other words, the length of the string in front of the fret (towards the Body) is the one that vibrates while the length of that string behind the fret (towards the Head) stays still. In other words, by pressing the string on any fret, you effectively change the length of the string that vibrates. Again, using our concepts of Physics, a longer string will vibrate slower than a shorter string. Which implies, that when you press a string on any fret the sound produced will be sharper. And that is how you change the sound in the creative process.
In a nutshell, there are 3 ways in which you can change the sound.
1. By changing the string that is played
Thicker string = Deep sound
Thinner string = Sharp sound
2. By tightening the string with the tuning keys
Looser string = Deep sound
Tighter string = Sharp sound
3. By pressing the string on any fret and changing the length of the vibrating string
Longer string = Deep sound
Shorter string = Sharp sound
Hope that made sense!
Let me know in the comments if you still have any doubts.
Also CHECK OUT this video wherein I explain these concepts