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 and is available as a self-guided course by Rice Online Learning on OpenStax AP Physics Collection: Rice Online Learning self-guided course: