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-15- <br />used to assess the future noise impacts of noise -generating <br />projects, such as modeling of airport noise. <br />,�,tig �e�a�uip��.e.�,,,@ogrLd level) deac�ip�or is th�a�taa�t <br />.,soured.-Lev*Lwthat-Ln-sixty...cnoaeCU".zJnutUjQ lid_po <br />same .anund.911g�4Y.8e_ t�.he.apkll9]...timezva=Yis9-s.ynightpa .n^„tea. <br />.level, It is based on noise energy and accounts for all noise <br />during the assessment period regardless of duration. _Thp-1eq UL. <br />-the ,capability -to assess -noise without the six and 30aninute...tima. <br />restraints.attached tQ_t11e,.L10 and..LSO. Through the development <br />of new, microprocessor controlled measuring devices, Leg can be <br />easily measured, and the contributions from different sources can <br />be added. It lends itself to calculation models, where the noise <br />level is generated by varying numbers of sources (e.g., passbys). <br />The Federal Highway Noise Prediction Model as well as a number of <br />other models use Leg as the primary descriptor. The fact that <br />Leg is in wide use in noise modeling efforts will be helpful to <br />the Agency in evaluating various project that muet be reviewed by <br />the Agency as to future compliance with noise standards. The Leg <br />is not without disadvantages, however. It does not give <br />information about the time history of noise, and specific sources <br />may produce noise which is annoying to the receiver without <br />exceeding the applicable Leg standard. This is also somewhat <br />true with the statistical Llo, L50 standard if the noise from a <br />source is sporadic. In addition, there are many community noise <br />programs which have adopted the Agency's existing standards by <br />reference and which have as a result developed monitoring <br />