not all pieces written after that need quite such a large orchestra, but concert halls had become bigger and composers had got used to a bigger variety of sounds. later composers sometimes added all sorts of unusual instruments: wind machine, sandpaper block, bottles, typewriter, anvils, iron chains, cuckoo, swannee whistle etc. none of these are normal orchestral instruments. sometimes a piano is used in the percussion section, e.g. igor stravinsky used one in "petrouchka". sometimes voices are also used.