What word signifies a loud outcry or public noise?

The word that signifies a loud outcry or public noise is "clamor." This term is often used to describe a situation where there is a strong and loud demand or outcry from a group of people, typically in a public setting. Clamor conveys a sense of urgency and collective voice, often seen in protests, public debates, or any scenario where many individuals express their opinions or desires emphatically.

In contrast, the other terms do not convey the same meaning. "Coerce" refers to the act of persuading someone to do something by using force or threats, which does not relate to noise or outcry. "Coalesce" means to come together to form one mass or whole, lacking any connotation of loudness or public expression. "Canvass" involves soliciting opinions or votes from individuals but does not imply a loud or public noise; it usually suggests a more methodical and quieter process.