Acoustics is the study of sound. It reveals the science behind the art, such as the subtle nuances of a Baroque symphony in terms of its constituent acoustic waves, but it's much more than that. As an acoustics major, you'll study the physical makeup of sound and its production: wave theory, the acoustic wave equation, vibration, reflection, "singularity expansion theory," and a host of other intricate-and interdisciplinary-concepts.
After you graduate, if you opt not to continue your studies in graduate school (although many acoustics majors do pursue advanced degrees), you'll be well-equipped to launch a career alongside architects (designing buildings) or biologists (studying the use of sound by animals, such as echolocation with dolphins), or in the fields of health diagnostics, aeronautics, underwater acoustics, engineering, and many other options. You'll need a sharp, inquisitive mind that is flexibly creative as well as a math- and physics-savvy. And you'll never hear an echo quite the same way again.