Symphony orchestra (a.k.a. Philharmonic) is one of the largest acoustic ensembles in western music. A modern symphony incorporates four sections based on the families of instruments: strings, woodwinds, brass and percussion. Specialized instruments, such as the harp, can be added for particular pieces. “Symphony” can also refer to a piece written for this ensemble, typically in multiple movements, such as the nine symphonies written by Beethoven or the four symphonies written by Johannes Brahms.