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r 3.4 Noise Non-Transportation Noise Sources t ' Non-transportation noise sources are commonly considered to be any source of noise on private s� property.San Joaquin County utilizes the performance standards of the Development Title to i assess impacts associated with non-transportation noise sources, including all sources of noise ' t originating from the project site(e.g., asphalt plant equipment,water trucks, loaders). �- Leq: the equivalent sound level is used to describe noise over a specified period of time, j typically one hour, in terms of a single numerical value. The Leq is the constant sound level which would contain the same acoustic energy as the varying sound level,during the same time period(i.e.,the average noise exposure level for the given time period). I Lmax: the instantaneous maximum noise level for a specified period of time. rL&/DNL: 24-hour day and night A-weighted noise exposure level which accounts for the greater -^ sensitivity of most people to nighttime noise by weighting noise levels at night ("penalizing"nighttime noises).Noise during nighttime hours(10:00 p.m. and 7:00 F# a.m.)is weighted(penalized)by adding 10 dB to take into account the greater annoyance of nighttime noises. ' 5 SEL: The equivalent sound level over a I-second time interval for a discrete sound event (e.g.,truck passby). E General Effects of Noise r The effects of noise on people can be placed into three categories: • subjective effects of annoyance,nuisance, dissatisfaction; �.._ • interference with activities such as speech, sleep, learning; and • physiological effects such as hearing loss or sudden startling. k For the average person, environmental noise typically produces effects in the first two categories. Workers in industrial plants or others exposed to high noise exposure for extended periods may also f experience physiological effects.There is no completely satisfactory way to measure the subjective effects of noise, or the corresponding reactions of annoyance and dissatisfaction.A wide variation in individual thresholds of annoyance exists, and different tolerances to noise tend to develop based on an individual's past experiences with noise. r Thus, an important way of predicting human reaction to a new noise environment is the way it compares to the existing environment to which one has adapted. In general,the more a new noise ' exceeds the previously existing ambient noise level,the less acceptable the new noise will be judged 3 � by those affected by it.With regard to increases in A-weighted noise level,the following relationships generally occur assuming that the introduced noise is of a similar character to sources composing the ambient noise environment: 1 3 � Munn 8 Perkins Quarry Excavation Permit 3.4-5 ESA 1211486 Draft EIR April 2011