It is of utmost importance to note that the Sound-Space approach to subsonic compressibility effects is an exact solution to the problem. That is, equation 19.5 is an exact relation between the compressible and incompressible local pressure coefficients. Nowhere in the preceding analysis was it necessary to make simplifying assumptions such as small perturbations, etc. It is true that the Sound-Space Theory assumes steady reversible–adiabatic flow and consequently it is to be expected that there will be discrepancies in the calculated and experimental values.

The validity of the physical principles upon which the Sound~Space Theory was founded and the consequent exact solution to the problem of subsonic compressibility effects, should signify an important advance to the better understanding of compressable fluid phenomena.