At a rock concert the engineer decides that the music isnt l

At a rock concert, the engineer decides that the music isn\'t loud enough. He turns up the amplifiers so that the amplitude of the sound, where you\'re sitting, increases by 90%. (a) By what percentage does the intensity increase? ( its not 361 %) (b) How does the intensity level (in dB) change? dB

Solution

The intensity of a sound wave is proportional to the amplitude squared

so if A = 1.90*A0 then the intensity I will be 1.90^2*I0

= 3.61 times the initial intensity

Since the dB scale is logarithmic then it will increase by

10*log(3.61) = 5.57dB