Room Modes in an 11x19 ft Room with a 10 ft Ceiling

Mode spectrum

Each line is one standing wave. Axial modes, the strongest kind, stand tallest; tight bunches and wide empty stretches are where the bass will sound uneven.

Axial modes by dimension

What this means for your room

• The lowest room mode is 29.6 Hz, set by the 19 ft length.
• Between 29.6 Hz and 51.2 Hz there are no modes at all, so notes in that 21.6 Hz gap will sound thinner than the bass around them.
• Mode density drops in the 40 Hz third-octave band (0 modes against 1 in the band below), so bass will sound uneven from note to note.
• The proportions (1 : 1.10 : 1.90) fall outside the Bolt area because the room is long and narrow for its height, so modes bunch up along the length.
• Below about 164 Hz (the Schroeder frequency) individual modes shape the sound; above it, reflections and reverb matter more.

This room has a hole of 21.6 Hz between 29.6 Hz and 51.2 Hz where no mode helps the bass along. Anything tuned to that range reads weaker than its neighbors.

For a home theater, expect that gap to color explosions and sub-bass hits unevenly rather than smoothly. For a music room, it means you cannot fully trust what you hear in the low end at the listening position, since a note that sounds loud in the room may be perfectly balanced on the recording.

The proportions (1 : 1.10 : 1.90) fall outside the Bolt area, the range room ratios usually spread modes best over, because the room is long and narrow for its height, which bunches modes up along the length. That does not rule the room out, but treatment is doing more of the work here than shape is.

How to fix it, in order

1. Start with bass traps in the four floor-to-ceiling corners; every mode in this room peaks there.
2. Full absorption at 40.0 Hz would take about 7 ft of trap depth, well past what any room can fit. Fill the corners as deep as you reasonably can (6 to 12 in, with an air gap behind), then lean on a membrane trap tuned near that frequency, your seat position and a second subwoofer with EQ to tame the note itself.
3. Do not sit dead-center on the 19 ft length. Start near 7.2 ft from the front wall, about 38% of the way back, and adjust from there.
4. For the subwoofer, try a few spots before settling: a front corner usually gives the most output but also the most uneven bass, while pulling it off the wall or adding a second sub often smooths out peaks like the ones this room has.
5. After treating, run an REW sweep from the seat. Everything below 164 Hz is where these modes live, so that is the range worth checking before you call the room done.

Every mode below 200 Hz

Below are all 78 modes this room produces under 200 Hz: 12 axial, 37 tangential, 29 oblique. Axial modes, which only involve one pair of opposite surfaces, ring the loudest. Tangential modes (four surfaces) come next, and oblique modes (all six surfaces) are the weakest of the three.

Questions about 11x19 rooms

Is an 11x19 room good for a home theater?

At 209 sq ft, this size works as a bedroom theater or dedicated music room, but a modal score of 65/100 means it is workable, not effortless: there is a gap of 21.6 Hz between 29.6 Hz and 51.2 Hz with no mode in between, so plan on real bass trapping.

Where do bass traps go in an 11 by 19 ft room?

The four vertical corners first. Full absorption at 40.0 Hz would take roughly 7 ft of trap depth, so treat that note with a tuned membrane or pressure trap instead, and use thick porous corner traps (6 to 12 in) for everything above it.

Do I need a big subwoofer for an 11x19 room?

Room size here mainly shapes where the modes land, not the sub size on its own; this room has 78 modes below 200 Hz to work around either way. Larger rooms like this one ask more of a subwoofer's output, and a second sub in a different spot helps smooth out the peaks and dips across seats.

Why do some bass notes sound weak in an 11x19 room?

In this room, the main cause is that there is a gap of 21.6 Hz between 29.6 Hz and 51.2 Hz with no mode in between. Room modes reinforce specific notes more than others no matter how good your speakers are, and that unevenness is what you are hearing.

How many bass traps does an 11 by 19 ft room need?

Start by treating the four corners with traps as thick as you can fit (6 to 12 in) plus a membrane trap tuned near 40.0 Hz, since that note's own quarter wavelength (about 7 ft) is too deep for any panel. Next, shift your listening position toward 7.2 ft from the front wall, then confirm progress with an REW sweep under 164 Hz.

Similar room sizes

• 10x19 ft, 10 ft ceiling
• 12x19 ft, 10 ft ceiling
• 11x18 ft, 10 ft ceiling
• 11x20 ft, 10 ft ceiling
• 11x19 ft, 8 ft ceiling
• 11x19 ft, 9 ft ceiling