The loudness level of a sound, D, in decibels, is given by the formula D = 10 log(10¹²I), where I is the intensity of the sound, in watts per meter2. Decibel levels range from 0, a barely audible sound, to 160, a sound resulting in a ruptured eardrum. (Any exposure to sounds of 130 decibels or higher puts a person at immediate risk for hearing damage.) Use the formula to solve Exercises 117–118.

What is the decibel level of a normal conversation, 3.2 × 10^-6 watt per meter²?