Wright then “read the letter to the whole school over the public-address system.”
The signal had been transferred by inductance in the wall wiring and amplified over the public-address system.
The music was piped in to the great hall over the public-address system.
A public-address system for a large area may give out fifteen watts of noise.
The plaza facing the Hall of Congress was filling up with citizens who had come to hear the speech over the public-address system.
People were being ushered to nearby classrooms where they would hear the proceedings over the school's public-address system.