ALARM, ALERT, AMPLIFIER, ANNOUNCE, ANNOUNCEMENT, AUDIO, BACKGROUND, BLUE, BRIGHT, BROADCAST, BROADCASTING, CLOUD, COMMUNICATION, DAY, ELECTRIC, ELECTRICITY, EQUIPMENT, HIGH, HORIZONTAL, HORN, INFORMATION, LIGHT, LOUD, LOUDSPEAKER, LOUDSPEAKERS, MANY, MEGAPHONE, MESSAGE, METAL, OBJECT, OLD, OUTDOOR, POLE, POST, POWER, PUBLIC, SHOUT, SIREN, SKY, SOUND, SPEAK, SPEAKER, SYSTEM, TECHNOLOGY, TOWER, VINTAGE, VOICE, VOLUME, WARNING, WHITE, WIRE, WITH,