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ZEN <br />COMPARISON OF SOUND LEVEL ATTENUATION <br />15 <br />MEMENEEMMEN <br />30i <br />250 <br />I <br />MMMMMMMMEMMMMWMN <br />M <br />M <br />EIMMMMMEMEMMAMEM <br />i <br />Environnienud Conditions <br />'Fen. iperature 50"F <br />Relative Hunu*dity 501;,� <br />—APA <br />NMNAIM <br />PAJIMM <br />i 0 <br />FAA <br />MMMAPA <br />M <br />FME <br />011 <br />M <br />I Pjam <br />MWIMI <br />MIX <br />W-MEAPAP <br />PMM <br />. <br />P <br />4pd <br />MMMMME <br />0 <br />- rAO-.,d <br />0 <br />Im 1 <br />0- 1 <br />a <br />10MM <br />5 <br />MMMMMIAF <br />MM-MEEMOMMIM <br />PA <br />pam <br />MINE <br />PIES <br />M-MME <br />MMPA4AOPAAF <br />0.90911M <br />ME <br />MEN <br />MR.Op <br />mop <br />_40 <br />WMM <br />101001011M <br />_AMMMMMMM <br />MOM <br />MMIE, <br />1000 2000 3000 <br />DISTANCE (Feet) <br />Siren Frequency dbc <<r Attenuation <br />100, <br />((1 4000' <br />A <br />500 <br />124 <br />- 8 <br />B <br />800 <br />124 <br />- 10 <br />C <br />1000 <br />124 <br />- 12 <br />D <br />1200 <br />124 <br />- 15 <br />E <br />1400 <br />124 <br />- 1 1.5 <br />At four thousand feet Siren A is 9.5 (11) <br />louder ;more than 3001,1) than Siren E. <br />Other contributing factors of sound <br />attenuation are not considered in this chart <br />Several other factors include the following: <br />Inverse Square Loss (Spherical <br />Divergence.) <br />Barrier Effects —Topographical and man <br />made. <br />Ground composition and cover. <br />Wind. <br />11 11 •111 111 <br />By the above chart you will note that the <br />higher frequencies attenuate more at a dis- <br />tance. Amy five sirens that generate 124 dbc <br />at different frequencies will not perform <br />equally in sound press -re over extended dis- <br />tances. This should be , onsidered before <br />studying the impact of any other factors <br />which would also apply to each siren. <br />In d;scusstng sound :und frequency no <br />attempt is made by Mielen Engineering <br />Company, Incorporated to suggest the area <br />coverage of a siren station to be used in plan- <br />ning a siren system for your community, acid <br />no liability is assumed. Many local factors. as <br />previously noted, apply. <br />19 <br />