There are probably two closely related key questions that concern people about noise exposure and hearing loss: First, what are the chances of getting a hearing loss from being exposed to some noise for some period of time? Second, how much noise exposure is acceptable before it becomes damaging to hearing? These questions are addressed by damage risk criteria (DRC) , which are standards or guidelines that pertain to the hazards of noise exposure. However, this apparently straightforward issue actually involves many interrelated questions, the answers to which are complicated, not necessarily understood, and often controversial. Some questions deal with the noise and predicting its effects: How should noise be quantified for the purpose of assessing damage risk, and how should we handle different kinds of noises (continuous, impulsive, intermittent, and time varying)? Are there valid and reliable “predictors” of NIHL, and if so, what are they and how are they related to heari...