We present a review of our studies of persistent spectral holes mainly in chlorin-doped polystyrene, frozen n-octane and p-terphenyl under pressures up to 8. 4 kbar at 4. 2-15 K in isobaric-isothermal experiments. In polystyrene and n-octane, narrowing of holes under pressure was observed and interpreted by the pressure dependence of lowfrequency pseudolocal vibrations. In p-terphenyl a drastic increase in holewidths was detected in the phase transition region around 5. 5 kbar at 4. 2-14 K.