How the Guitar Works

The guitar is a stringed musical instrument that is played using the fingers of both hands on a fretboard. When a string is plucked it vibrates and transmits energy to the sides and back of the guitar, where it is amplified by vibrations in the body to produce sound through a speaker.

There are many types of guitars, including acoustic and electric guitars. The inner workings of a guitar vary slightly depending on the type but are largely the same for all guitars.

A truss rod is a thin, strong metal rod that runs along the inside of a guitar neck. The truss rod helps to maintain the correct shape of the neck by countering changes in curvature caused by string tension or aging of the wood neck materials. It can be adjusted by turning a hex nut or allen key located at the headstock, underneath a cover, or on some electric guitars through the sound hole.

A guitar’s strings are made of metal or nylon. They are wrapped around tuning pegs, which are attached to the body of the guitar and are used to tune the strings. The tuning pegs are used to raise or lower the pitch of a string, so that the string can be tuned to match other strings on the instrument. Tightening a string increases its pitch, while loosening it decreases its pitch. The thickness of a guitar string also affects its pitch; a thicker string has a lower pitch than a thinner string.

The vibration of a plucked string causes the walls of the guitar’s body to vibrate, particularly the front wall. This is a form of Helmholtz resonance. You can experience a similar phenomenon by blowing across the top of a bottle. Air has a natural springiness, so when it moves into the body of the guitar it pushes back out through the soundhole. As the ‘lump’ of air moves out, it creates pressure that pushes on the ‘lump’ of air moving into the guitar, and this cycle continues.

The amount of energy a string retains before it decays is determined by the material of the nut and saddle and how tightly the nut is tightened. For example, a plastic nut and saddle will absorb more of the vibrational energy than a wooden nut or saddle. A more flexible acoustic guitar soundboard will absorb less of the energy, allowing the string to vibrate for a longer time and produce a louder note before it decays. The trade-off is that the note produced will have less sustain (how long it lasts before it dies out).