According to David Holmes, the textual or behavioural qualities of…

Concept — a medium is not a neutral pipe. In medium-centred communication theory the architecture of a channel — the technical and social arrangement that fixes how many people may address how many, with what degree of reciprocity, and at what speed — sets the conditions under which every exchange carried on it takes place. The form of the channel is treated as an explanatory level in its own right, prior to any particular content.

Application — Holmes on the first and second media age. David Holmes (Communication Theory: Media, Technology and Society, SAGE, 2005) builds his contrast between a broadcast first media age and an interactive second media age on exactly this premise: the textual and behavioural qualities of communication are determined by the architecture of the particular medium. A broadcast architecture (one-to-many, centralised, with no return path) produces one set of textual and behavioural qualities — an address to an anonymous mass audience, reception without reply. A networked, interactive architecture (many-to-many, decentralised, reciprocal) produces another — exchange between participants who can answer back and become senders in turn. Change the architecture and the qualities of the communication change with it, so the blank takes medium.

Cross-check — why the other levels of analysis do not fit the blank.

• Message is the content that a channel carries. Holmes’s claim is that this content is conditioned by the architecture rather than being that architecture, which is why medium theory is often summarised as looking past content.

• Noise belongs to the Shannon–Weaver transmission model, where it names interference that degrades a signal in transit. It describes a disturbance within an exchange, not the structural form that organises exchanges.

• Ideology names a system of beliefs and values and belongs to critical and cultural analysis of media. It explains how meaning is shaped at the level of ideas, a different order of explanation from the material and technical form of a channel.

Result. The architecture Holmes refers to is the architecture of the medium.