Consider the one-dimensional wave equation
subject to the boundary conditions
You may assume the sound speed and density is constant for 
a. Show that the boundary condition at x = D represents the reflection from a plane interface separating two fluid media.
b. Assume that [0; D] represents an acoustic medium with c = 1500m/s and = 1000 kg/m3, and that D represents an interface to an acoustic halfspace with c2 = 1600m/s and = p = 1800 kg/m3. Find the corresponding value of.
c. Assume that the boundary pressure P(t) is of the form
Derive the analytical solution for 