A meeting room is bought on an equipment list. An auditorium is judged on whether the person in row twenty can follow the argument, and that is a different question with a different answer.
Scale changes the physics. Past a certain volume the room's own reverberation sets the ceiling on intelligibility, so the fix lives in the ceiling and the wall treatment before it lives in the equipment. Speech intelligibility is measurable: the Speech Transmission Index, defined in IEC 60268-16, gives a number for each listener position, which is why the measurement belongs before the specification.
Sightlines and control change with it. Pitch is chosen from the closest viewing position, whatever the size of the room, and brightness from ambient light measured in the actual space. The person running the room on an ordinary Tuesday is rarely the person who specified it, so the control has to survive the handover.
Questions Worth Taking Forward
- What does the back row actually hear, and has anyone measured it?
- Who operates this room on a day when nothing special is happening?
- Which constraints belong to the building rather than the budget?
- What has to be true before an equipment list is written?