Question

A decibel meter reads a sound intensity of 80 dB when you stand 2 m from a loudspeaker. What will the meter read (in dB) if you stand 40 m away?

Answer 1

Step-by-step explanation:

L₁ =80 dB

S₁ = 2 m

S₂ = 40 m

__________

L₂ - ?

The intensity of the site is nearby:

ΔL = 10·lg(S₂/S₁)²

ΔL = 10·lg(40/2)² = 10·2·lg(20) = 20·1.3 = 26 dB

L₂ = L₁ - ΔL = 80 - 26 = 54 dB