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1 <br />1 <br />i <br />1 <br />'1 <br />1 <br />1 <br />'1 <br />~1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />t <br />1 <br />TABLE 3.6-1 <br />TYPICAL VALUES! OF YEARLY DAY-NIGHT AVERAGE SOUND <br />LEVELS FOR VARIOUS RESIDENTIAL NEIGHBORHOODS WHERE <br />THERE IS NO WELL DEFINED SOURCE OF NOISE OTIIDR <br />THAN USUAL TRANSPORTATION NOISE <br /> <br />.::.::.:.......:..:.....:..::::..:::::.:::::.:.:::::.::: <br />... . ...:.::...... <br />:.:::Pb tlatiori:Densi ::'::.:.:.:. <br />.:::.:' ;. :. ;;. <br />:.'.:' ::::::::"::::.:::;:.:..'::::;:::':'•:::.::::.::::: <br /> ,....: <br />Rural{undeveloped) 20 35 <br />Rural (partially undeveloped) 60 40 <br />Quiet Suburban 200 45 <br />Normal Suburban 600 50 <br />Urban 2,000 ~5 <br />Noisy Urban 6,000 60 <br />Very Noisy Urban 20,000 65 <br />iltese values aze logazithmic measuremenu (i.e., every 10 dBA increase in noise level is perceived <br />by the human ear as approximately twice the noise level). <br />Source: National Academy of Sciences 1977 <br />Sheet 1 of 1 <br />