The clavichord is a European stringed keyboard instrument known from the late Medieval, through the Renaissance, Baroque and Classical eras. Historically, it was mostly used as a practice instrument and as an aid to composition, not being loud enough for larger performances (a problem that was solved when the Clavinet was invented in the mid-20th century). The clavichord produces sound by striking brass or iron strings with small metal blades called tangents. Vibrations are transmitted through the bridge(s) to the soundboard. (source)