1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Sound Waves from a loudspeaker

  1. Oct 16, 2003 #1
    I've been stuck on this one problem for a bit, any help is really appreciated.

    "A loudspeaker is placed between two observers who are 110m apart, along the line connecting them. If one observer records a sound level of 60.0 dB and the other records a sound level of 80.0dB, how far is the speaker from each observer?"

    I've been having a tough time grasping sound waves in general actually. These problems usually take me alot longer than the previous chapter on wave motion. So I was also wondering if anyone knew some good help sites with sound waves, I seem to only find ones with formula's on them.
  2. jcsd
  3. Oct 16, 2003 #2
    My guess is that the decibel scale was created for just such a problem. That is,

    80~P/x3.2 and 60~P/(110-x)3.2

    where P is the power at the speaker, x is the distance for the 80dB observer, (110-x) for the 60dB observer, and the approximation that the sound intensity drops off as the 3.2 power of distance is assumed. (Remember, 23.2=10) Solve the two equations by eliminating P.
  4. Oct 16, 2003 #3
    thanks alot!
  5. Oct 16, 2003 #4
    I hope I'm right, Lipd.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook