You're convinced the opera is almost over because of the large women singing a loud vibrato.
(a) If the sound intensity level (dB) increases from one note to the next by 1 dB, what is the percent increase in the intensity? The singer comes over to your side of the stage, only 10 m away, and your phone applet tells you the sound intensity level is 85 dB.
(b) What is the power coming from her voice? All of the sudden 4 more identically loud women come out of nowhere and join her - you think to yourself, will it ever end. Three of them are standing next to her and the forth is on the other side of the stage, twice as far from you as the group of singers.
(c) What is the sound intensity level now?