Hyperacusis (decreased sound tolerance) can be extremely troublesome for affected individuals and their families. Many terms are used to describe sound tolerance symptoms in the clinical literature, and this has led to some confusion. There are associations between hyperacusis and otologic, developmental, neurological, and psychological disorders, and these are described. Work is underway regarding physiological mechanisms, with an increase in central auditory gain an area of interest, but this work is emergent at present. There is a clinical association between hyperacusis and tinnitus, with 40% of persons with troublesome tinnitus also experiencing decreased sound tolerance, but causality is not yet understood. The evaluation of a patient with hyperacusis involves a careful history and a cautious approach to audiological investigation, particularly regarding assessment of loudness tolerance. Questionnaire instruments exist for the assessment of hyperacusis, but none are designed for use with children. Many unanswered questions about decreased sound tolerance exist, and some of these are described.Learning Outcomes: As a result of this activity, the participant will be able to (1) list definitions and terminology of decreased sound tolerance symptoms and (2) describe the approach to evaluation in this patient group.A decrease in the ability to tolerate sound can have a markedly adverse effect upon an individual and their family. The 21st-century sound environment is replete with sounds of moderate to high intensity, both used intentionally to alert us (alarms, alerts, and announcements) and as part of the environmental soundscape (e.g., public transportation, grocery shopping, or attending school). The response of the individual with decreased sound tolerance