This soft-voiced keyboard instrument, already popular in the 15th century, looks like an oblong box. Thin strings extend from the left over the soundboard bridge to tuning pins on the right. Keys are on one long side. By depressing down a key, the far end of the key lever see-saws upward until a tooth-like metal tangent protruding from it presses a set of strings. This produces both tone and pitch. When tangent pressure is released, felt cloth woven among the strings on the left automatically dampens the sound. Minute changes in finger pressure can offer a vibrato, or subtle variations in dynamics and articulation, making the clavichord an extremely sensitive and expressive keyboard instrument.