The acoustic guitar is a fretted stringed instrument. It is a member of the ‘lute family’ which includes stringed instruments such as steel-string acoustic guitars, 12-string acoustic guitars, nylon string classical and flamenco guitars, and bass guitars, harps, mandolins, and ukeleles.
The guitar player plucks or strums the strings using a plectrum or fingers to produce sound, and frets the strings at different positions on the neck to control the pitch of the notes played.
How Acoustic Guitars Produce Sound
Acoustic guitars utilize resonance to produce sound acoustically through the vibration of the guitar’s strings.
The vibrations from the strings are transferred to the guitar’s body via the bridge of the guitar, and projected via the soundboard (top of the guitar) and internal chamber of the guitar, producing a wide range of frequencies influenced heavily by the tonewoods the guitar is constructed from.
Alternatively, acoustic-electric guitars can be played acoustically or amplified via a pickup (microphone, piezo, or magnetic soundhole pickup), much the same as the electric guitar.
You can read more about how the acoustic guitar works here.
The Parts Of An Acoustic Guitar
An acoustic guitar consists of two major components, the neck, and body.
The neck features a fretboard divided into frets. Each fret is equal to one semitone, increasing in pitch (while also narrowing logarithmically) the further toward the upper frets of the guitar the note is played.
The neck also features a headstock that contains 6 tuning pegs used to tune the guitar to the desired pitch for each string.
Running through the center of the neck is the truss rod. This adjustable steel rod is used to adjust the neck relief.
Lastly, the neck is joined to the body via the neck pocket, which is usually a mortise and tenon joint.
The hollow body of the guitar consists of an upper and lower bout, a soundboard (the top wood of the guitar), soundhole, bridge, saddle, and back and sides. Higher quality guitars tend to be all solid wood construction, while laminate is often seen on less expensive models.
Inside the body, the top and bottom of the guitar are braced, to provide additional vibrational strength to counter the tension from the steel strings.
The length of the guitar string able to vibrate is referred to as the scale length. The two points of contact for the string (unless fretting a note on the fretboard) are the nut that sits near the headstock and the saddle which is located within the bridge.
You can read a detailed article about the anatomy of acoustic guitars here.
How Acoustic Guitars Are Made
Acoustic guitars are made by luthiers.
One of the most important aspects of building an acoustic guitar is sourcing materials with good acoustic properties (tonewoods) such as Spruce, Mahogany, and Cedar. These tonewoods are light, yet strong. This is particularly important for the soundboard, which responds to the energy imparted on the strings by the guitarist.
Once the materials are chosen the body is shaped, the soundhole cut, and the bracing added to the back and top, along with linings added to the sides to increase the surface area for adhesives to be applied.
The neck is constructed next (in most cases) and joined to the headstock using a scarf joint. The neck is then joined to the body with a dovetail joint. The fretboard, one of the most important components of the guitar is made next. The fret spacing is calculated and is crucial in terms of intonation.
Lastly, the guitar is finished with a clear lacquer, and sanded and buffed to a fine finish. Hardware such as tuners is then added along with the bridge, nut, and inlays for the fretboard.
This is a basic overview of how acoustic guitars are made, depending on the guitar manufacturer and type of guitar the process can vary. For a detailed overview of the building process, you can read more here
Types of Acoustic Guitars
While there are smaller guitar-like instruments such as the Guitalele (a hybrid of guitar and ukelele) for the most part, there are 5 main body types of acoustic guitar, based on size and body shape. From smallest to largest, this includes:
Also commonly referred to as a size 0 concert guitar. Parlor guitars are the smallest type of acoustic guitar. The neck connects to the body at the 12th fret and the body itself is elongated.
Parlor guitars usually feature a strong fundamental tone and are particularly well suited to fingerstyle.
Commonly referred to as a size 00 the Concert body style is just a touch larger than the parlor, featuring a tighter waist which gives the guitar a rounder look.
The tighter waist reduces surface area beneath the soundhole, reducing bass output and accentuating the response to higher frequencies. As a result, concert-sized guitars typically sound brighter than parlor guitars.
Also commonly known as 000 or Auditorium.
For a long time, the orchestra guitar was the standard size for guitars. Featuring a tighter waist than both concert and parlor guitars, but a larger body this style of guitar is normally more pronounced in the mid-range and very balanced.
The Dreadnought shape is the most popular acoustic body size available today. Dreads are a popular choice as they are louder than smaller body guitars, and are considered a versatile option in terms of their tonal output.
Due to their wide waist, the typical dreadnought offers a powerful, boomy, low end, and looks ‘blocky’ in comparison to Parlor and Concert guitars.
As the name suggests, the Jumbo is a large guitar capable of producing more volume than smaller body guitars such as parlors, and concert models.
Due to the size of the guitar, and internal cavity space, along with the tighter waist when compared to the typical dreadnought, the Jumbo guitar offers a more balanced output than it’s size might otherwise suggest.
For a far more detailed look at acoustic guitar body styles and sizes click here.
Who invented the acoustic guitar?
While it’s true that the first nylon string guitar was made by Spanish Luthier Antonio Torres Jurado, it is more accurate to say Antonio Torres Jurado standardized the guitar. This was achieved through the revolutionary bracing system he developed, known as fan bracing (the bracing allowed for the soundboard to be larger) which in turn allowed for greater volume and projection.
On the back of the first classical guitar, the first steel-string acoustic was created by Christian Frederick Martin of C.F. Martin & Company. The bracing system he developed (X bracing) paved the way for the commercial production of steel-string acoustic guitars.
Both Antonio Torres Jurado and Christian Frederick Martin are pioneers, but the truth is mankind has been playing stringed ‘guitar-like instruments (Chordophones) for centuries.
While there is some conjecture over which primitive instrument most influenced the design of the acoustic guitar. Instruments such as the Kithara, and Oud played a role in influencing the design of the Lute and the renaissance period Vihuela, which bears a closer resemblance to the modern acoustic guitar.
Click here to read a detailed article about who invented the acoustic guitar.
Hopefully, this article has provided a basic understanding of what an acoustic guitar is, how it works, the different types available, and the acoustic guitar’s development over the years.
If you enjoyed this article, be sure to check out some of our other articles discussing the intricacies of the acoustic guitar.