An aeolian harp (or æolian harp or wind harp) is a musical instrument that is "played" by the wind. It is named for Aeolus, the ancient Greek god of the wind.

Aeolian harps were very popular as household instruments during the Romantic Era, but are still being hand-crafted today. Some are now made in the form of monumental metal sound sculptures located on the roof of a building or a windy hilltop.

The traditional aeolian harp is essentially a wooden box including a sound board, with strings stretched lengthwise across two bridges. It is placed in a slightly opened window where the wind can blow across the strings to produce sounds. The strings can be made of different materials (or thicknesses) and all be tuned to the same note, or identical strings can be tuned to different notes.

The sound is random, depending on the strength of the wind passing over the strings, and can range from a barely audible hum to a loud scream. If the strings are tuned to different notes, sometimes only one tone is heard and sometimes chords.

The harp is driven by an aeroelastic effect. The merest motion of a string across the wind forces the air on the leading side to move faster than that on the trailing side; then (see Bernoulli's principle) the pressure ahead is slightly less than that behind, pushing the string further to the side, until the restoring force arising from deflection halts and reverses the motion.

The effect can sometimes be observed in overhead utility lines, fast enough to be heard or slow enough to be seen. A stiff rod will perform; a non-telescoping automobile radio antenna can be a dramatic exhibitor. And of course the effect can happen in other media; in the anchor line of a ship in a river, for example.

Aeolian harps in literature and music

Aeolian harps are featured in at least two Romantic-era poems, The Aeolian Harp and Dejection, an Ode, both by Samuel Taylor Coleridge.

The Etude in A flat major for piano (1836) by Frederic Chopin (Op. 25, no. 1) is sometimes called the "Aeolian Harp" etude, a nickname given it by Robert Schumann. An impassioned melody is picked out by the fifth finger of the pianist's right hand, over a background of rapid pedaled arpeggios. Sound file of a performance, with sheet music, from ChopinFiles.com

External links

• Building aeolian harps, with images; in English and German.
• The Æolian Harp