Answer
$$1.5 \mathrm{nW} / \mathrm{m}^{2} .
$$
Work Step by Step
We can use Eq. $17-27$
$$
I=\frac{1}{2} \frac{\left(\Delta p_{m}\right)^{2}}{\rho v}=\frac{1}{2} \frac{\left(1.13 \times 10^{-3} \mathrm{Pa}\right)^{2}}{\left(1.21 \mathrm{kg} / \mathrm{m}^{3}\right)(343 \mathrm{m} / \mathrm{s})}=1.5 \mathrm{nW} / \mathrm{m}^{2} .
$$
