Abstract: Radio signaling apparatus is for use, primarily, in classrooms at all educational levels, elementary school through graduate school, in which a teacher and a mixed body of hearing and deaf students participate in a lecture and discussion situation with the support of a trained interpreter in sign language. The radio system comprises a voice actuated pulsed omnidirectional radio transmitter, which is worn by the teacher, and a plurality of portable receiving devices, one for each deaf student. The microphone of the transmitter is selected to discriminate against ambient sounds and background voices. The omnidirectional receivers detect the pulsed radio transmissions and generate by transducer action a non-audible sensory stimulation to alert each individual deaf student, whereupon each such student should renew his or her observation of the interpreter. In a preferred embodiment the radio apparatus provides a flashing visual signal from each deaf student's receiver.