An improved 3-dimensional musical keyboard apparatus comprises a plurality of planar, longitudinally extending keys mounted for both downward depression and longitudinal displacement; spring components to return an unguided key to its at-rest position; means to limit the extent of key motion; sensing means to detect key position at any point in its range of motion; and electronic digital signal processor means responsive to key position signals and productive of musical control information. Additionally, it comprises a single line of contact structure for restraining keys from lateral motion; differential damping for the vertical and horizontal components of key motion; simplified means for signaling key center position in the displacement axis; and support for musical articulation in the direction of key displacement when a key is moving upward from a depressed position.