Barker (noun)

A person who makes loud and persistent calls in order to attract people's attention, especially to promote a show or product.

Origin:

From the action of barking or calling out in order to draw attention.

Examples:

1. The barker was trying to attract customers to come see the carnival show.
2. The barker's loud voice could be heard from blocks away.
3. At the county fair, the barker invited people to step right up and try their luck at the games.
4. The barker's job was to entice people to come inside the tent and see the amazing sights.
5. The barker's persistent calls were finally answered when a curious family approached to learn more.