[填空题]
(a) Estimate the power output of sound from a person speaking in norma/ :pwg9bxf.mgju2zw(,zr( jgf9 y8 u el conve dxq4 2cc3w( c5*kz vvdid.8ggrsation. Use Table 12–2. 35* d(v84c2.v iqwkcggxc ddz Assume the sound spreads 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
