We tend to associate the sciences with seeing-but scientists, engineers, and physicians also use their ears as a means for acquiring knowledge. This chapter introduces this essay's key questions about the role of sound and practices of listening in the sciences, and explicates their relevance for understanding the dynamics of science more generally. It defines the notion of sonic skills, situating it in the wider literature on the auditory dimensions of making knowledge. It presents the case studies on which the essay draws, explaining their geographical, temporal, and methodological scope and the researchers behind them. Keywords Listening for knowledge • Sonic skills • Science • Medicine • Engineering Acoustic signAtures On the afternoon of July 11, 2014, Dutch Public Radio 1 broadcast an interview with science journalist Diederik Jekel. He had breaking news: American geologists had discovered a "super ocean" some 300 miles below the earth's surface. The journalist immediately added a qualification. What the Americans had actually found were some stone minerals, originating from the earth's deep layers, that included water molecules. This prompted the talk show host to ask how certain scientists could be of the super ocean's existence. The journalist explained that the CHAPTER 1