Sociopsychological factors affecting the human response to noise exposure

Community noise is reported to be the most often mentioned undesirable neighborhood condition in a recent U.S. Census survey. Understanding community response to noise involves the measurement of a number of complex acoustic and nonacoustic variables and establishing the chain of relationships between physical exposure, perception, annoyance, and acceptability responses and finally complaint behavior. The perceived loudness of a noise is the most important acoustic parameter influencing annoyance and complaints, and the simple dBA unit can be used to integrate spectral characteristics of complex sounds in community studies. Although energy averaging such as Leq or Ldn can be used to describe multiple noise exposures over time, the variable trade-off relationships between number and level of exposures are somewhat obscured by such summary measures. However, they are still the best available descriptors and, until more accurate ones are developed, can be used to measure community noise environments. Perception of an identical noise exposure can vary according to the physiological noise sensitivity of a person and the activity context in which the noise is heard. Although the acoustic quality of the noise itself usually explains about 10 to 25 per cent of the variability in annoyance responses, sociopsychological variables measured in field studies account for 35 to 50 per cent of the variations in human annoyance responses. Three of the most important nonacoustic factors are the connotative fear effects of the noise signal, the feeling that those responsible for the noise are misfeasant in not reducing the noise, and the feeling that harmful health effects are produced by the noise. When residents report great fear, a high misfeasance, and marked health effects, about 90 per cent report a high annoyance level whether their noise exposure level is above 90 Ldn or 65 to 70 Ldn. In contrast, if the feelings are a low fear level, a low degree of misfeasance, and minimal health effects, only 3 to 10 per cent give high annoyance responses. Complaint behavior, although based on intensity of annoyance, is modified by a number of other sociopsychological factors and often is an unreliable indicator of an environmental problem.