Honestly, I'm not sure where the dividing lines are myself. I just know that when I hear the dimensions, and calculate the cubic footage, I usually can give a reasonable assessment of what is required.
For example my room is 11.5'W x 18'L x 8'H for a total of 1656 cubic feet. That falls somewhere in the upper small to lower medium sized room. But, my listening area is only 11.5'W x 8'L x 8'H. That's the only space my speakers need to cover. That is definitely small (particularly compared to SirQuack's room
) .
It's a bit different when considering subwoofers. You have to take into account all the space when trying to figure out how much subwoofer you need. It is generally accepted that in order to get pants-flapping bass out of a sub, it needs to "pressurize" the entire area. My room is open to a 10' x 10' dining area, and an approximately 4' x 5' foyer. That brings the total cubic footage to 2616 cubic feet. That's still not a huge space, but it's not small either. Happily my EP500 does the job.
Maybe others who have a more concrete concept of small, medium, and larger spaces will chime in.
EDIT: Whoops! Terzaghi already did.
