Question

. At your apartment, you hear the busy road (the dB level of a freeway is 80 dB from 1.00 m away) and measure the noise at a constant level of 45 dB. a) What is the power output of traffic on the road? b) How far away is your house from the road? c) How far from the road would you need to be for the sound to measure at 20 dB? d) Town Hall is planning to add panels along the road that would absorb 70% of the sound energy (reduction in the power). What is the expected decibel level of road sounds at your house after the panels are installed?

Answer 1

ap 18 A o solna Sound lovel Cloundness in given log where is thresold Intensity of the eair given by [10 Ixto 12 wym I 0 o I 2 Now hinnatus power to Area (A) IT R2 R tistance Then = Plane? ko 9 T Ro3 Io PROR Ri 2 po Hence Z stondag to log ? Ro log to R2

DATE: D due to Traffic Noise distance at a 1 m us 80 dB Then 80 How mesured by lo tog t R² Po 112 man in apartment 45 dB Prien is from = 10 to tost k k A part ment Now 4.5 Po (442 has distance (a) the rod. équation o equuton fo. 45 oftast P Roboth B Po (112 god ..=10 А tog A-lag B tieg 35 To 3 = to top d² toy a 35 33 2010 or logd 35 Antitog 2.75 To m Auntilog. (1.751 = 10 56.23 m d

DATE: again from equation 2 m once and So to log log I 1 Io I2 Io 45 lo de dog I I Antiloge (8) ! or Io or Io & co 8 Totto СТЬ 612 w/ m² by definitie f 4 Thie I z to whom W/m2 II 4 t/m² if the power produced by the traffit To then P 2 = 5 To T2 Xlo T HET R2 47c02 f 4X/ 7 12-56 xto to Р = 1.256 mW 6 from the equation dz 56.23m

PAGE NO DATE: 7 a If af mesure distance (r) & B we 20 then P Ro? To tog = lo loy & Ro² et fo s bo U2 tgivela hen. 21 forgo top Left I Ro? po 22 60 to togh 2 e por e 81 B to titanol @ Power P produced by traffic t. 256 mW This Then 70% of le P oot 70 70 x 7.256 you o.8792 mW Р Then व E Intensity mesured at apartment 911 (56.23)2 ou879 28,03 983 148 (56.2372 2.22X108 W/m2

A PAGE HO DATE: Then I Io tog 2.2 1108 en peded decibel to lay to tog 2.29 X10 lx612 I loy 2.29 + toy tot § 1o e 4 titog.2.217 toftto.3449 Yox 4.3444 4 3.499 & B 2