On the cover

Built in 1968 by the Danish company Marcussen & Son, the pipe organ pictured here is located in the New Cathedral in Linz, Austria. Its 5890 pipes are divided into 70 rows, known as stops, that each have a different sound character. The pipes in an organ need to be tailored to the acoustics of the space in which the instrument will be installed. To learn more about pipe organ acoustics, see the Quick Study by Judit Angster, Josep Llorca-Bofí, and András Miklós. (Photo by Uoaei1/Wikimedia Commons/CC BY-SA 4.0 /cropped and brightened from original.)