[填空题]
(a) Estimate the power outp z9q 1d pz.:bgr7eul n4;(kstb-rk44w bo9i ejut of sound from a person speaking in normal conversation. Use Table 12–2. Assume the sound s4row-9jkei 4bpreads roughly uniformly over a sphere centered on the mouth. $\approx$ $ \times10^{ -6}$W(Round to the nearest integer)
(b) How many people would it take to produce a total sound output of 100 W of ordinary conversation? [Hint: Add intensities, not dB’s.]$\approx$ $ \times10^{7}$people
