SOLUTION: If you are at a rock concert and take a loudness reading at 100 feet from the sound source and get a reading if 110 dB, how do you determine what the loudness would be at a distanc

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: If you are at a rock concert and take a loudness reading at 100 feet from the sound source and get a reading if 110 dB, how do you determine what the loudness would be at a distanc      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 1034007: If you are at a rock concert and take a loudness reading at 100 feet from the sound source and get a reading if 110 dB, how do you determine what the loudness would be at a distance of 50 ft from the source. And what distance do you need to move away from the source to get a reading under 90 dB?
Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
L1 and r1 are the reference loudness and reference distance, then
:
L2 = L1 - | 20 * log (r1 / r2) |
:
L1 = 110 and r1 = 100
:
***********************************************
L2 = 110 - | 20 * log (100 / 50) | = 116.02
:
at 50 feet the loudness reading is 116.02 dB
***********************************************
:
r2 = r1 * 10^( |L1 - L2| / 20)
:
r2 = 100 * 10^( |110 - 90| / 20) = 1000
:
*******************************
r2 is 1000 feet
*******************************