How Do Pianos Work?

The piano is a fabulously complex mechanism. It is a systemization of an older, manual convention of striking the strings of a lute with tiny soft hammers. Later, musical device makers fashioned the harpsichord, which plucks the strings with quills at the push of a key. The harpsichord was intended to replicate the sound of a harp but replace the human hand as the as the active initiator for the string. Touch, after all, is inconsistent and characterized by error. The piano, rather than plucking the string, strikes it with a felt-covered mallet, about as wide as a finger. When the musician depresses a piano key, the following mechanism is activated:

Sitting as it does on a fulcrum, the key’s opposite end raises and applies upward force to a system of levers.

The lever system produces a flick of pressure upon a hinged hammer, causing the hammer to launch upward at the string. Each hammer has its own string of varying length and tuned to a specific pitch.

The hammer strikes the string and, since it approaches from beneath the string array rather than over it, immediately falls away under the force of gravity, allowing the string to vibrate without interference.

As you might imagine, the tiny hammer and the flick that activates it are both delicate and the sound they produce on the string is faint. The real genius of the piano is how it sustains the string’s vibration and amplifies the sound it generates. At the end of string array is a block of wood, upon which the strings rest. This is called the bridge, and it as a conduit capturing the vibration coming off the string and releasing it into the soundboard that sits at the bottom of the piano’s frame. The soundboard is ribbed and made of very fine wood. It absorbs the vibration given to it by the bridge and distributes it across its entire breadth. The planar soundboard has much more surface area than the single string and can agitate a great deal more of the air surrounding the instrument, allowing it to resound throughout a hall or auditorium.

Typically, the soundboard is made from light, pliable balsam. The very best soundboards every manufactured were made from whale cartilage. Piano makers would shave a razor-thin panel from the whale’s lung cavity and leave it to dry until it was rigid and capable of keeping shape. Sometimes, for stability, they would rib the sheet of cartilage with bird bones, which they grafted together under intense heat. The process was incredibly laborious, but the music made by these cartilage soundboards was otherworldly. When the last piano manufacturer to use this practice went out of business in 1896, Debussy is said to have contemplated giving up the piano altogether, saying that playing the instrument with just a simple wooden soundboard felt like eating bark.

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