Echo Chamber
If we have a limited group of people and the dynamics of Spiral of Silence are applied, the number of dissenting opinions will decrease to the point were no one will challenge the narrative and accelerate group think. This is called an Echo Chamber.
Echo chambers work within a group of people, and they amplify a message which is already planted in that group. Hence, their usefulness is not to recruit new followers but to solidify the beliefs of a person or a group. In extreme cases, echo chambers may even be used to radicalize the audience. An example of an echo chamber is a technical discussion forum which has a relatively limited audience. Over time, ideas will converge in a particular way; in addition, people who feel their opinion is not popular would be less likely to post messages (which itself is a manifestation of the Spiral of Silence).
Echo Chamber is not to be confused with a Filter Bubble. The latter is a phenomenon where the computer algorithms in a person’s online environment form their view of the world as they only show information which the algorithms “think” would be most relevant (or capturing) to the individual. In turn, this effectively isolates them from other information because it is not deemed interesting to the user or worse, because it is deprioritized, or censored, due to some agenda.