Question

A person standing a certain distance from fifteen identical loudspeakers is hearing a sound level intensity of 112 dB. What sound level intensity would this person hear if three are turned off?

Answer 1

Sound level intensity of 15 identical loudspeakers at a certain distance = ₁ = 112 dB

Sound intensity of 15 identical loudspeakers at this distance = I₁

I₁ = 0.1585 W/m²

Now three of the loudspeakers are turned off therefore 12 loudspeakers are working.

Sound intensity due to 12 loudspeaker at this distance = I₂

I₂ = 0.1268 W/m²

Sound intensity level due to 12 loudspeakers at this distance = ₂

₂ = 111.03 dB

Sound level intensity the person would hear if three loudspeakers are turned off = 111.03 dB