The sound power level of an outdoor non-directional point source is 90 dB

Q. The sound power level of an outdoor non-directional point source is 90 dB. Considering an atmospheric impedance of 400 rayls, the sound pressure level at 10 m distance from the source is _______dB.

Ans: 58 to 60

Sol:

Putting values of L_w = 90, r = 10 m, L_p = 59,00 dB
(No role of atmospheric impedance)