Asume that the sound level of your whisper is 20 dB and is shout is 90 dB. How many times greater is the intensity of a shout than a whisper, given that the decible level of a sound wave is related to the intensity I of the wave by : ( d B = 10 log " I I_ 0 ) Where I 0 = 10 -12 Wm -2 .