How Does a Guitar Produce Sound?
A guitar comprises three basic parts: strings, body, and neck. It produces sound by pressure placed on its strings by fingers and/or a plectrum (i.e. a pick). This creates a vibration that moves up and down the body and neck of the guitar. The airflow transfers into the body of the guitar and results in sound waves.
Although a simplified explanation, this is the basic premise of it. There are many factors that go into how a guitar makes sound. This includes the shape of the body, the length of the neck, and the type of strings along with the overall materials of the guitar.
How Does an Acoustic Guitar Make Sound?
Acoustic guitars have a hollow body with a neck and head. The head contains tuning pegs that allow for the tightening and loosening of the strings. The front face of the guitar is the soundboard and this is where the soundhole is. It helps to project and deliver music outward.
Attached to the soundboard is the bridge. This is where one end of the strings affix through the neck and up to the head where the tuning pegs are. The bridge will often have a hard and thin piece called the saddle. This is the area where the strings rest and stay secure.
When the strings vibrate on an acoustic guitar, the resonance (vibration + air) travels through the saddle to the bridge and into the soundboard. This causes the whole soundboard to vibrate as well. The hollow body amplifies these vibrations to audible levels.
How Do Acoustic Guitars Work?
The parts and variables of an acoustic guitar work together in such a way as to determine the sound. Things like the materials, size and shape of an acoustic guitar will affect the resulting audio. This includes the face of the neck, otherwise known as the fingerboard.
When fingers press down on specific spots in the neck, also called frets, it creates lower or higher pitched tones to create variations in sound; otherwise known as “notes.” This sound resonates throughout the guitar, transmitted to the side and back through the air in the body projecting out from the soundhole.
The light wood that comprises the soundboard is a crucial factor in not just producing sound but affecting sound quality. This includes the pickguard installed around the soundhole.
How Does an Electric Guitar Make Sound?
Electric guitars make sound in a very similar way as acoustic guitars. Actually, they are much alike in a host of ways. For instance, they both have six strings, tuning pegs, frets, and long necks. But, the difference in their sound is in the body.
Some electric guitars will have hollow or semi-hollow bodies with a resonating cavity, just like an acoustic. However, most of the popular models of electric guitars are solid with the sound projecting from pickups installed on the soundboard. The pickups sit under the strings and are magnetic, controlled by a series of several knobs.
And, as the name suggests, an electric guitar will need power to be audible. So, if you strum one of the strings when unplugged, you won’t hear anything. This is why you need an amp and a cord to connect the guitar.
How Do Electric Guitars Work?
Electric guitars work mostly by their magnetic pickups. When the string vibrates, it cuts through the magnetic field generated within the pickups when electric power is running through. This produces a signal within the pickup’s coil.
This signal then travels to the amplifier and speaker. These are often bar magnets wrapped in thousands of fine, coiled wires. When electric energy runs through this magnet, it becomes electromagnetic which turns motion, vibration, and resonance into sound.
However, there are several types of pickups. Some have a single magnetic bar under all the strings simultaneously. Yet others have individual poles for each string with an accompanying screw. This allows for adjustment to fine-tune the sound for the desired effect.
But most guitars will have two or three differing pickups in varying spots on the body. Each has a distinct sound. When there are multiple pickups, they can pair up to produce even more variations in sound.
Amplifiers & Speakers
All this is possible through the use of an amplifier and speaker. Without them, no sound would be audible. This is because electric guitars are passive; they don’t consume power but the string’s vibration signal via the pickups does require it.
There are three components to an amp: pre-amp, power amplifier, and speaker. Some models feature reverb circuits and sound effects too, which occur between the amplifier and pre-amp. The pre-amp boosts the signals generated by the pickups which actually drive the power for the amplifier.
The amp takes the signal and makes it audible by way of boosting the power and sound to drive the speaker. This means the amp is an essential component to being able to use the instrument successfully. It allows for a musician to play with a range of sounds that can be distorted and “dirty” or clean and crisp.
Distortion & Feedback Loops
Distortion occurs when the circuitry of the amp can’t handle the heavy signal put through the pickup. This is very desired, especially in the rock-n-roll, punk, and metal genres as well as in blues, jazz, and some country. The most famous musician known for his use of distortion is Jimi Hendrix.
Another fun aspect to using an electric guitar and an amp is the advantage of feedback loops. This is when the sound from the amp is so loud that it causes the strings to vibrate on their own. As an example, when a player strikes a note directly while facing the amp, the vibration will continue indefinitely.
Conclusion – How Does a Guitar Produce Sound?
Whether an acoustic or electric guitar, it produces sound through the resonance that occurs after a string’s movement. This subsequently results in an audible projection we otherwise know and call, “notes” and “music.”
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