A subspace damping field is a field that can be deployed by a starship in which the nature of subspace is altered to disallow any motion or communication through the field. Objects and energies passing through in normal space are unaffected. (TNG: "I Borg")

In 2367, the impostor styling herself as Ardra employed a subspace damping field to interfere with the normal operations of the USS Enterprise-D. Lieutenant commander Geordi La Forge was able to detect and penetrate it, making contact with the Enterprise. (TNG: "Devil's Due")