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Stringed Instruments: Good Vibrations

Some of the most popular musical instruments seem like nothing more than a piece of wood and some metal strings. So just how does that result in the timeless art of music?

Though the swaying chirp of a tiny Hawaiian koa-wood ukulele strum and the deep, purring baritone of a contrabass may seem worlds apart, they are united by the same basic rules of physics. As a musician manipulates a string, whether by plucking it with a pick or brushing it with a bow, it vibrates at a specific frequency, creating a small, almost indiscernible sound. Within the delicately constructed body of the instrument, however, the sound resonates and amplifies, emerging as the full, sonorous timbre of a dad noodling on his old banjo in front of your friends.

The frequency at which a string vibrates depends upon its tightness and length. When a musician presses down on a string, it becomes shorter, resulting in a higher frequency (or pitch). In this way, a guitarist can strum an almost infinite combination of notes and chords by controlling the given pitch of only six strings.

Despite the common underlying physics, a variety of factors help to create such a diverse range of sounds among stringed instruments. When playing a fiddle, for instance, the bow simply glides across the strings, resulting in a fluid, even tone. A banjo, on the other hand, has a large round body with a resonating drumhead that creates its characteristic twang. Even the piano, though not technically a stringed instrument, operates on the same principles: tiny hammers inside the body strike individual strings, each carefully tuned to a specific pitch, producing percussive, dynamic notes among several octaves. Still, the differences between any two instruments are subtle, and even with modern tools, few cellos and violins can compete with Stradivarius’ 18th-century pieces crafted with unique woods, varnishes, dark incantations, and hours upon hours of care.