Int. J. Environ. Res. Public Health 2010, 7 3734 Another study investigated the relationship of noise and blood pressure and a stress response included a quality of life survey to noise exposed subjects. Evans et al. [2] looked at children that lived in a noisy “airport” community and a quiet community. They measured systolic and diastolic blood pressure, urine epinephrine, norepinephrine, and cortisol levels, as well as obtained results from the KINDL quality of life questionnaire. They found that there was an increase in blood pressure in the noisy communities. There was also a significant increase in urine epinephrine and norepinephrine levels, but not a significant change in cortisol levels. The KINDL questionnaire is an assessment of quality of life in children and has been proven to produce reliable results [39-41]. This questionnaire was used in this study and found that the quality of life in the children living in the noisy community declined significantly over the 18 months of the study [2]. Sleep Disturbance and Cognitive Impairment Noise can cause disturbances in sleep and subsequent deleterious health effects and perceived decrease in quality of life [42]. Noise can cause immediate or secondary extra-auditory effects. The number and duration of nighttime awakenings can quantify the immediate effect of noise on sleep. Nocturnal awakenings usually occur with noise levels greater than 55 dB [42]. The time that it takes to fall asleep can increase up to 20 minutes with peak noise levels of 45 dB [43]. After approximately 5 hours of sleep the threshold of awakening lightens and noise can cause frequent early morning awakenings [42]. The secondary effects of noise on sleep are a subjective feeling of decreased quality of sleep, tachycardia, increase in stress hormones (as discussed previously), and increased cognitive impairment [44]. The perceived quality of sleep can be quantified by using any number of objective questionnaires, some of which include the SF-36, the Nottingham Health Profile, or the Functional Outcomes of Sleep Questionnaire to name a few [45-48]. These effects of noise on the sleep process may also contribute to the impairment of cognitive tasks and overall performance [44]. Noise may cause cognitive impairment from a variety of mechanisms. Earlier studies have demonstrated that children in noisy environments have decreased attention on tasks and have lower performance on cognitive assignments compared to children in quiet environments [49-52]. A more recent study by Ljung et al. [53] found that traffic noise significantly impaired reading ability and comprehension as well as basic mathematic performance in children. Previous hypotheses suggested that the cognitive impairment from noise was due to cognitive coping where children “tune out” excessive stimulation and have a generalized poor attention [52,54]. Another hypothesis was that noise caused a high level of arousal and resulted in an inability to concentrate [55,56]. These psychological and physiological non-auditory effects of noise result in detrimental health consequences and a decreased quality of life. 4. Conclusions This is just some of the evidence to highlight noise as an unwanted environmental pollutant that has global implications. In our industrialized society, a significant population is exposed to noise on a daily basis with its resultant health effects, and subsequent substantial economic burden. There has been a plethora of research on the mechanism of NIHL. The role of oxidative stress in NIHL has been extensively investigated and remains a probable cause of NIHL. This results in significant