The poly(vinyl acetate) (PVAc) segmental dynamics is studied as a function of composition, temperature, and pressure in thermodynamically miscible blends with poly(ethylene oxide) (PEO) by dielectric spectroscopy. In the PVAc-rich blends all short-range correlations are dominated by the PVAc component. An invariant frequency dispersion is found when the spectra at each blend composition are compared under isochronal conditions. The self-concentration model with a fixed PVAc self-concentration of similar to 0.22 qualitatively describes the temperature dependence of the PVAc segmental dynamics both at atmospheric and at elevated pressures.