Room Ratios: The example room dimensions (12′ high x 16′-10″ wide x 19′-11″ long) are based on the height:width:length ratios 1::. These particular ‘room ratios’ were chosen because they produce a room with relatively evenly spaced low frequency modes. This gives the room a flatter bass response than similar sized rooms with less optimal ratios. Acoustically, cubic rooms have the worst ratios (1:1:1). You may not be able to choose the size of your room… but if you can, avoid cubic rooms like the plague.
If you’re building your room from scratch, here are the best known dimensions for small listening rooms .