This concept trailer covers Physics of Hearing and corresponds to Chapter 17 in OpenStax College Physics for AP Courses. A cellist with impaired hearing gives our physical definition of sound. The factors controlling the frequency of a vibrating string are identified, as is the relationship among speed, frequency, and wavelength. A string’s first three standing-wave vibration possibilities (harmonics) are diagrammed and their wavelengths are identified. Full course content for the AP® Physics Collection on openstax.org and is available as a self-guided course by Rice Online Learning on EdX.org: OpenStax AP Physics Collection: https://openstax.org/details/college-physics-ap-courses Rice Online Learning self-guided course: http://online.rice.edu/mooc/course/preparing-ap-physics-1-exam-part1-linear-motion/