Combined exposures to noise and chemicals can cause more hearing loss than exposure to either agent alone. Vibration and extreme heat are also potentially harmful to hearing when combined with noise. The emphasis on prevention rather than conservation also reflects a change. The shift from conservation to prevention is not minor. Conserving hearing means to sustain the hearing that is present, regardless of whether it is impaired or not.
Prevention means to avoid creating hearing loss.
Conservation can start when one is first exposed to an occupational agent that is potentially harmful to hearing. Prevention starts long before the first exposure. Conservation comes from a program that is created and imposed. An emphasis on prevention evolves from beliefs that it is not necessary to suffer an impairment, illness, or injury to hold a job and that it is within one's own purview to employ techniques, use behaviors, and rely upon personal protective equipment to prevent impairment, illness, or injury. The combined result of such changes as these has been to stir the core tenets of hearing loss prevention.