You have a thrust reverser duct that can be approximated as a long,

straight, rectangular duct with height of $0\mathrm{.}5$m and width of $5$m$.$ Assume

a negligible flow speed and a speed$-$of$-$sound equal to $340$m$/$s$.$

$$ If you can only acoustically treat $2$ walls of the duct, which ones would you

choose? Provide your reasoning.

$$ Estimate the best normalized resistance and reactance to maximize the

attenuation at $100$Hz Cross$-$section of duct