The equation y = 20 log (x/0.00002) measures the intensity of a sound as a function of the pressure it creates on the eardrum. The intensity, y, is measured in decibels (dB), and the pressure, x, is measured in Pascals (Pa).
a. What is the intensity of the sound of a humming refrigerator, if it causes 0.00356 Pa of pressure on the eardrum?
b. A noise that causes 20 Pa of pressure on the eardrum brings severe pain to most people. What is the intensity of this noise?
c. Write the inverse function that measures pressure on the eardrum as a function of intensity of a sound.
d. How much pressure on the eardrum is caused by a 90 dB sound?