A metaphoric image of the loudspeaker and its sides sums up the spatio-temporal ruptures that started shaping aural perception in the late 19th century: on one side, the listener; on the other, sound events conveyed by phonographic products, radio and various sound-recording devices. Diverse practices as well as samples of theoretical and aesthetic thinking from the early 20th century illustrate how new media have affected the musical imagination and listening in general.