Guitar sound is caused by a chain of events that begins with a finger or pick and ends in human perception. (That is, when we’re talking about non-percussive, “normal” guitar sounds). While both acoustic and electric guitars start with vibrating strings, the way that vibration becomes an audible sound—and eventually music—is very different between the two.

This article walks you through the complete process for both types of guitar, from pluck to perception. Enjoy, friends! 

When we pluck a string (by finger or pick), mechanical energy is applied to the string, setting it into motion. Where does this initial energy come from? Well, if we’re being scientific:

The energy began with the Big Bang. Over time it passed through stars, into sunlight, into food, into muscle—and was finally guided by our intention (or was it, perhaps, always guided by some sort of larger intention?). When you pluck a string, you’re converting ancient cosmic energy into sound.

Abstract stuff, huh? How deep we go into the rabbit hole when we strive for accuracy! 

Let’s get back to the physical pluck, which oscillates the string between two extreme positions. This motion is periodic (repeating at regular intervals) and approximates a sinusoidal pattern and fades over time, as shown below:

The frequency of vibration depends on three primary factors:

• String tension: higher tension yields higher frequency

• String mass per unit length: thicker strings vibrate more slowly

• Vibrating length: shortened by fretting

The fundamental frequency determines the pitch, while harmonics (integral multiples of the fundamental) determine the timbre or tone color.

What exactly are harmonics? When you pluck a guitar string, you’re not just hearing one pitch—you’re hearing a whole family of pitches all vibrating together. These are called harmonics.

The lowest and strongest of these is called the fundamental frequency. That’s the main note you hear (for example, the open low E string at 82.41 Hz—1 Hz is 1 cycle per second).

But at the same time, the string is also vibrating in pieces—like halves, thirds, fourths, fifths, etc. These extra vibrations create harmonics, and here's the cool part:

Harmonics Are "Integral Multiples"

That just means:

• 2 times the fundamental = 2nd harmonic

• 3 times the fundamental = 3rd harmonic

• 4 times the fundamental = 4th harmonic

• And so on…

So if your fundamental note is 100 Hz:

• The 2nd harmonic is 200 Hz

• The 3rd harmonic is 300 Hz

• The 4th harmonic is 400 Hz

The vibrating string alone does not move much air—it’s too narrow and light. To project sound, the energy must be transferred to a larger surface: the guitar’s soundboard.

• The bridge acts as the mechanical interface between the string and the top plate (soundboard).

• The soundboard, typically made of spruce or cedar, responds to the vibration by moving a large area of air.

• Simultaneously, the back and sides of the guitar form a resonant cavity that modifies and amplifies certain frequencies.

The air cavity inside the guitar creates Helmholtz resonance, which boosts bass response and provides tonal richness.

(Hemholtz resonance is the phenomenon where air in a closed space vibrates at a specific frequency when disturbed. You can also witness this effect with the sound produced when you blow across the top of a bottle.)

As the top plate and internal air vibrate, sound waves are radiated from the guitar—mainly through the soundhole.

• These sound waves are longitudinal pressure waves moving through air.

• Their speed (~343 m/s = 767 mph at room temperature) and interaction with room surfaces determine how the listener hears them.

Longitudinal means that instead of moving up and down like a wave on water, the air particles move back and forth in the same direction the sound is traveling: left, right, back to center. 

Many of these particles bump into each other and pass the energy along — like a row of falling dominoes or people doing “the wave” at a sports game.

“Pressure” = Squeeze Together and Spread Out

As the wave travels, it creates areas where air gets squished together (high pressure) and areas where it spreads out (low pressure). So what you’re hearing as music is a pattern of pressure changes through the air! 

Here’s a simple diagram of a sound source creating a pattern of crowded and spaced-out air molecules: 

How does a pressure-pattern of air molecules turn into something we can hear and enjoy?

1. Your Ear Detects the Sound: The sound waves reach your ears and cause your eardrum to vibrate. Tiny bones and fluid inside your ear carry those vibrations to a special part called the cochlea.

2. Your Nerves Translate It: Inside the cochlea are thousands of tiny hair-like sensors that turn those vibrations into electrical signals.

3. Your Brain Makes Sense of It: These electrical signals travel along nerves to your brain, which instantly processes them and says, “That’s music!” It recognizes rhythm, pitch, emotion, and even remembers similar sounds from your past.
    

In summary:

Vibrations → Air waves → Ear → Nerve signals → Brain → Musical Perception

 

Summary: Chain of Events from Action to Perception

Here’s the full process, organized into a simple table: 

Understanding how your guitar produces sound—from vibration to brain signal—can make you a more informed player and listener. Be sure to take advantage of your knowledge of acoustics, always getting the best tone and projection you can. 

Sound, at its core, is motion. Your job is to shape that motion in ways that feel meaningful—and knowing how it works can only help.

Thanks for reading!