 Aside from the many almost insurmountable technical difficulties of many modern pieces, some of them are hardly suitable for performance in a small room.For example, "Different Trains" by Steve Reich is scored for live string quartet and recorded tape, which layers together a carefully orchestrated sound collage of speech, recorded train sounds, and three string quartets.Since the invention of electrical telecommunication devices in the 19th century, players of a string quartet can even conduct a conversation when they are flying over the audience in four separate helicopters, as in the "Helicopter String Quartet" by Karlheinz Stockhausen.