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2. Terminolo_v <br /> a. Statistical Noise Levels <br /> Due to the fluctuating character of urban traffic noise, statistical procedures arc <br /> needed to provide an adequate description of the environment. A series of statistical <br /> descriptors have been developed which represent the noise levels exceeded a given <br /> percentage of the time. These descriptors are obtained by direct readout of the <br /> Community Noise Ana Id der. Some of the statistical levels used to describe community <br /> noise are defined as folio.cs: <br /> Lin - A toise level exceeded Ibr 10% of the time, considered to <br /> he an "inurtuive Ievel. <br /> I_ao - lbc noise level exceeded 504 of the time representing an <br /> "to eraue" sound level. <br /> Lon - fhr noise level exceeded 90 % of he time. designated as a <br /> "btcicground" noise level. <br /> L�.,t The <br /> continuous-NM n alent level is that level of a steady <br /> noise bovine the same energy as a given time-varying <br /> ioise. The Teti thus represents the decibel level of the <br /> .inre-averaged value of sound energy or sound <br /> aressure squared. The I.� is the noise descriptor used to <br /> _al_ulate the DNL and CNEI. descriptors. <br /> H-? <br />