One Pluck, Many Tiny Motions
Follow a single pluck as vibrations pass from an acoustic guitar's string through wood and air to a listener's ear.
Play the quiz as a gameA string by itself moves very little air, so its sound is faint. How can a guitar make that tiny motion easy to hear? An acoustic guitar solves this problem with its wooden body. It does not need a speaker. Follow one pluck to discover how.
From String to Wood
First, a finger pulls a string sideways and lets go. The stretched string springs back, but it does not stop in the middle. It moves back and forth very quickly. These repeated movements are vibrations. The string may look blurry because it is moving too fast for your eyes to follow each trip.
Next, the string passes vibrations to a wooden piece called the bridge. The bridge connects the string to the guitar's broad wooden top. As the bridge moves, the top vibrates too. This larger surface can move more air than the thin string can. The air inside the hollow body also vibrates, helping the guitar produce a stronger sound.
From Air to Ear
As the wooden top moves outward, it pushes nearby air particles closer together. As it moves back, the particles spread farther apart. These pushes and spreads pass through the air as a sound wave. The particles move back and forth near their starting places. They do not fly across the room from the guitar into your ear.
When the sound wave reaches your ear, it makes your eardrum vibrate. The eardrum is a thin piece of tissue inside your ear. Next, tiny bones carry the vibrations deeper into the ear. Parts of the inner ear change this motion into signals that travel to your brain. Your brain recognizes the sound. This whole journey happens very quickly.
What if you gently touch the ringing string? Your finger stops its vibrations. With no new motion coming from the string, the guitar's sound quickly fades. Picture a diagram of the journey with arrows from string to wood to air to ear. Its caption could read, 'One vibration starts the next motion.'