The intensity at the threshold of hearing for the human ear at a frequency of about 1000 Hz is lo = 1.0 X 10-12 W/m2, for which B, the sound level, is 0dB. The threshold of pain at the same frequency is about 120 dB, or l = 1.0 W/m2, corresponding to an increase of intensity by a factor of 1012. By what factor does the displacement amplitude, A, vary?