In turbomachine apparatus having alternating rows of stator blades and rotor blades, there is provided discontinuities or nonuniformities on the downstream facing surfaces of at least one row of stator blades, the nonuniformities being adapted to disperse pressure waves reflected from downstream rotor blades. The nonuniformities may be an arrangement of grooves, ridges, or a combination of grooves and ridges on the downstream facing blade surfaces; other surface discontinuity configurations are also possible, such as an arrangement of potruding surface elements or dimples, or force-absorbing material selectively deposited on the dowstream-facing portion of the blade surfaces.