Harp, musical instrument in which strings, sounded by plucking, run between a neck and a sound box. Harps are made in three basic shapes: arched harps, in which the neck and body form a bowlike curve; angular harps, in which neck and body form at least a right angle; and frame harps, in which a third piece, the forepillar, is placed opposite the angle between the neck and body, forming a triangle, to brace them against the tension of the strings. The modern orchestral harp is a large frame harp having 46 strings (six and one-half octaves, with 7 strings per octave); the bass strings made of covered wire and the treble strings of gut or nylon. To produce accidentals (sharped or flatted notes) lying outside the harp's seven-note scale, the instrument has a system of seven double-action pedals, each pedal controlling one string in every octave. The harp is tuned to the C-flat scale; when a pedal is depressed one notch, each string it controls is raised by a half step, as from C flat to C natural; when it is depressed two notches, each is raised a whole step, as from C flat to C sharp.
