The motivation for studying acoustic propagation in high enthalpy environments lies partially in the role that acoustics play in promoting laminar-turbulent boundary-layer transition. At high speeds, boundary-layer transition on slender-body vehicles is primarily due to Mack's second-mode instability. If the growth of disturbances is sufficiently reduced, then laminar- turbulent boundary-layer transition could be delayed or prevented. In many cases, maintaining laminar flow over a high-speed vehicle is beneficial because a laminar boundary layer exerts significantly less heating and shear forces on the vehicle than a turbulent boundary layer. Accurately capturing the physics of transition would allow for a more precise prediction of the transition location. Less uncertainty in the transition location would then allow for optimization of thermal protection systems and design of high-speed vehicles. Thus, it is important to understand the interaction of an acoustic wave with a high-enthalpy flow environment.