Habermas

Habermas argues that the development of early modern capitalism brought into being an autonomous arena of public debate.

The public sphere is an area in social life where individuals can come together to freely discuss and identify societal problems.

Curran & Seaton

The idea that media should have the right to be exercised freely.  It is used as a defence for public service broadcasting and the impact that social media has on the audience.

Chomsky

Manufacturing Consent. The political economy of mass media. This book was released in 1988. The authors try to propose that the mass communication media of the US are effective and powerful ideological institutions that carry out a system-supportive propaganda function, by reliance in market forces.

Ownership: mass media firms are big corporations and are often part of even bigger conglomerates, their goal is profit and they will push for whatever guarantees that profit. 

Advertising: exposes the role of advertising. As media costs a lot more then consumers pay, advertisers fill the gap and pay for audiences. 

The Media Elite: the establishment manages the media through the third filter. Elite news companies have the resources to ease the news-gathering process. 

Flak: flak refers to the negative commentary to a new story or journalist. Flak includes lawsuits, complaints, petitions, and government sanctions. 

Anti-Communism and Fear: this filter still operates; it mobilises the population against a common enemy (terrorism etc) while demonising opponents.