The speaker’s job in Jonas’s community is a combination of enforcement and announcements. For example, when the jet flies overhead, the speaker tells everyone to drop their bicycles and go inside, presumably to protect them from the possible danger. However, the speaker also is used for public shaming. When Jonas takes an apple home to inspect it for changing, the speaker makes an announcement that reminds him of the rule against hoarding food.
The only thing that happened was the announcement later that evening over the speaker, the announcement that had singled him out without using his name, that had caused both of his parents to glance meaningfully at his desk where the apple still lay. (Ch. 3)
The announcement is effective, even though it does not name him. All Jonas’s parents have to do is look at him. They know that the announcement refers to him. By making the announcement, the speaker reminds everyone in the community that they are always under surveillance. Resistance is futile. The speaker keeps them in line. When Jonas starts his training, he is surprised that The Giver can flip the switch on the speaker. No one else can.