The Apple Hearing Study is a partnership between the University of Michigan and Apple to study of sound exposure and its impact on hearing health. This groundbreaking study will advance our understanding of how hearing could be impacted over time by exposure to sound at certain levels. We will measure headphone and environmental sound exposures over time among our participants, and determine how these exposures impact hearing and stress levels. Our study will provide us with a better understanding of listening behavior and its overall impact on hearing health. This information will in turn help guide public health policy and prevention programs designed to protect and promote hearing health in the US and globally. Our study has four objectives: • To understand typical headphone listening patterns and sound exposures, and their relationship to current and future hearing health; • For Apple Watch users, to understand typical environmental sound exposures, and their relationship to current and future hearing health; • To study how participants interact with data about their own headphone listening patterns and environmental sound exposures; • For Apple Watch users, to understand the relationship between environmental sound exposures and cardiovascular health.