How Acoustic Guitars Work

If you’re the type of person that likes playing an acoustic guitar more than any other instrument, you will surely like to add an analog device such as a tape delay pedal to your collection. Also, before we discuss how an acoustic guitar works, maybe you should have a look at our article about cheap acoustic guitars. To better understand how an acoustic guitar produces the sound we will discuss how the guitar parts work toward the same purpose.

The body

The part of the guitar that is the largest and holds the acoustic properties is called the body. Its shape and size have a great influence on how the guitar sounds. The purpose of this part is to transmit the vibrations coming from the strings to the air around it. That is why it needs a large surface area, to be able to push air in and out better and create more volume.

However, the body is not an amplifier, it doesn’t produce more power than the player puts into the strings when plucking them, but it allows for more efficient conversion of the energy put into the strings. This is not similar to the process that an electric pickup goes through, where the signal is amplified, regardless of how hard the strings are struck.

There are different guitar shapes, each providing a certain kind of sound. In terms of size, the bigger the instrument, the more power is needed to achieve a good sound. So, if you have a big guitar, you will have to hit the strings harder and that will also produce a louder sound.

The top plate, or soundboard

Although the body is made of more pieces, the one that sits on top, the face of the guitar is the most important. And that is because it’s the piece that needs to be flexible and vibrate. It should move up and down with ease, and to do that it is usually made of spruce or other kinds of wood that are flexible.

The soundboard is impressively light and slim, measuring 0.1 inches. And because it’s so thin, it needs to be supported by a series of braces to strengthen it. These also act as a way of keeping the top plate flat, as the plate is subjected to intense pulling forces from the strings.

Another effect that the braces have is they influence how the top plate vibrates. Other parts of the body aren’t so important from an acoustic point of view. The back plate doesn’t have a big impact on that, as it touches the player’s body most of the time and that reduces its acoustic properties.

Also, due to their shape and relatively small width, the lateral panels of the body don’t vibrate too much and don’t move perpendicularly. Thus they also have little to no influence on the sound.

The strings

As you might expect, the strings moving is what actually produces the sound. The rule is that, if you want a sound, you need to make something vibrate. For a musical note to appear, that vibration needs to be a constant one, resulting in a stable pitch. This pitch or constant frequency must also be controlled by the player.

In acoustic instruments, the sound and its stability are created by something named a standing wave. If you film a string being struck and then slow down the recording, you will see that the string acts like waves. How heavy a string is has a direct effect on the sound, as the more massive ones vibrate slower and thus produce a thicker sound, a bass one.

Guitars that use steel strings have their strings increase in diameter from one to the next one. But in classical guitars, the change in diameter is more complicated. In these guitars, there are 3 nylon strings and they get thicker from E to B to G, and there are 3 other strings that are wire-wound nylon and they get thicker from D to A to E.

What also changes the frequency at which strings produce their sound is how tight they are. Using the tuning pegs you can adjust their tension, and the tighter they are, the higher their pitch. This is how you tune your strings, by making use of this principle.

Another factor that is to be taken into account when considering the pitch of the strings is how long or short they are. A shorter string will produce a higher pitch, and this effect is used when playing the guitar when you press the string against a certain fret.

On their own the strings don’t produce much noise, that’s why they need a body to amplify their waves. That is why electric guitars can hardly be heard when not plugged in because they don’t have an acoustic body.

The neck and fretboard

Without these, the guitar will produce the same 6 notes at all times. Usually made of hard types of wood, the neck is an important structural component and its duty is to stay as strong as possible, without bending. If the neck warps or bends, the resulting notes will vary without the player being able to control them.

Although it needs to be strong, the neck also has to be light, as you want a balanced guitar, not one that hangs too much on the left hand, if the player is right-handed. When the neck is too heavy, it applies too much pressure on the hand and wrist and in the long run, this will mean problems for the player.

To solve these issues, acoustic guitar necks are made of light types of wood and they have a metal rod that runs through their middle in order to provide more sturdiness. On the neck, you have the fretboard, which has the function of allowing the player to alter the musical notes that come out of the guitar.

As explained in the section about strings the frets separate the fretboard into sections that are half-a-tone apart. When the player presses a fret, the part of the string that vibrates gets shorter and the pitch changes.