Smart keyboard learns your moves to give a voice to the voiceless

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adults or Children; age greater than or equal to 6 y.o. * Male or female * Able to (a) spell, (b) follow 2-3 step directions, (c) read 40 point text * Have complex communication needs representing a broad spectrum of developmental and acquired severe motor impairments resulting from high spinal cord injury (SCI), chronic Guillain-Barre syndrome, brain stem stroke, cerebral palsy (CP), locked-in syndrome, among others. * Requires the use of an alternative access strategy to communicate and/or use technology that has been clinically prescribed and manually optimized following current clinical standards. * Sufficient control and voluntary muscle activation on either the head, hand, or foot (on the basis of clinical evaluation by clinical collaborators at University of Nebraska Medical Center) to use the proposed wearable AAC system for the purpose of this study. * Sufficient stamina and developmental maturity (on the basis of clinical evaluation by clinical collaborators at University of Nebraska Medical Center) to attend to the approximately 1-2 hour protocols outlined in Aims 2 and 3 without excess fatigue or distraction. * Availability for at least 5 testing sessions over the study period. * No medical or safety restrictions of active head, hand, or foot movement (as determined by clinical collaborators at University of Nebraska Medical Center). * Clinical evidence of preserved cognition by a score of 0 or 1 on NIHSS Consciousness and Communication item. * Ability to voluntarily blink eyes or raise eyebrows on command (for head selection) or contract fingers/hand grasp (for hand selection) or rotate foot (for foot selection). * Able to provide written, informed consent or an accompanying communication partner or parent/guardian (for individuals under 18 y.o) to provide written, informed consent/assent to participate in the study. * Able to speak and follow directions in English. Exclusion Criteria: * Non-English speaker. * Inability to follow simple instructions in English. * Medical history of musculoskeletal conditions (arthritis, spondylosis, etc.) that causes pain on head, hand, or foot movement. * Restricted active or passive rotation of head and neck resulting from unstable vertebral, spinal cord, or nerve roots that places the subject at risk for execution of the protocol. * Medical history of cardiac or respiratory complications, or similar disorders that would severely reduce stamina and/or place the subject at risk for conducting the different motor activities. * Unable to provide informed assent/consent in English.