[填空题]
Workers around jet aircraft trkg,qgp/ o+b hr1hn8:j 2p;q aypically wg6 j-9c z0lfeyear protective devices over their ears. Assume that the sound l-y0cz9gle 6 jfevel of a jet airplane engine, at a distance of 30 m, is 140 dB, and that the average human ear has an effective radius of 2.0 cm. What would be the power intercepted by an unprotected ear at a distance of 30 m from a jet airplane engine? W
