Two friends are walking, having a normal conversation; the sound level of the conversation if 60 dB...Calculate the new sound level.

Question

Two friends are walking, having a normal conversation; the sound level of the conversation if 60 dB. When they get near a busy street, they have to double the intensity of the sound to be able to hear each other. Calculate the new sound level.

Grade 12 Advanced Functions

Please write clearly, neatly, and straightforwardly.

Thank you.

Answer 1

Let x = the sound intensity for 60dB = 10log(x)

dB = 10log(x)

Doubling

dB = 10log(2x) = 10(log(2) + log(x)) = 10 log(2) + 10log(x)

= 10log(2) + 60

≈ 3 + 60 = 63 dB

In general, whenever you double the intensity, add 3dB. Whenever you halve the intensity, subtract 3 dB.