Room Modes in an 11x22 ft Room with a 9 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 25.6 Hz, set by the 22 ft length.
• Your 22 ft length is exactly twice your 11 ft width, so their modes stack at 51.2, 102.3 and 153.5 Hz and bass at those notes will be much louder than its neighbours.
• Your 22 ft length and 9 ft ceiling height both resonate near 125.0 Hz, so bass at that note will be much louder than its neighbours.
• Between 25.6 Hz and 51.2 Hz there are no modes at all, so notes in that 25.6 Hz gap will sound thinner than the bass around them.
• Mode density drops in the 31.5 Hz third-octave band (0 modes against 1 in the band below), so bass will sound uneven from note to note.
• The proportions (1 : 1.22 : 2.44) fall outside the Bolt area because the room is long and narrow for its height, so modes bunch up along the length.
• Below about 161 Hz (the Schroeder frequency) individual modes shape the sound; above it, reflections and reverb matter more.

The modes from your 22 ft length and 11 ft width land on top of each other near 51.2 Hz. That stack means one specific low note gets reinforced twice, so it jumps out over everything nearby.

For a home theater, expect that stacked note 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 : 1.22 : 2.44) 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. Put your first traps in the four vertical corners where floor meets ceiling; that is where every mode in this room reaches its loudest point, ceiling height included.
2. Full absorption at 51.2 Hz would take about 5.5 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. Avoid the exact middle of the 22 ft length for your seat or mix position; try around 8.4 ft from the front wall (38% of the length) as a starting point, then nudge from there by ear.
4. Test more than one subwoofer position. Corner placement drives the most output but also the least even bass; moving it along a wall or using two subs at different spots tends to average out this room’s peaks.
5. Confirm the fix with an REW measurement at the listening position, paying closest attention below 161 Hz; above that, general room reverb matters more than any single mode.

Every mode below 200 Hz

This room has 81 modes below 200 Hz, 13 axial, 40 tangential and 28 oblique. Read the axial rows as the ones you will hear most clearly. Tangential and oblique modes add texture but usually only become audible when they land close to an axial mode.

Questions about 11x22 rooms

Is an 11 by 22 ft room good for a music room or home theater?

This size is workable for a bedroom theater or dedicated music room, but its modal score of 20/100 is low, driven by the fact that two of its dimensions reinforce the same note near 51.2 Hz. Go in expecting a serious treatment plan.

What is the best corner for bass traps in an 11x22 room?

The four vertical corners first. Full absorption at 51.2 Hz would take roughly 5.5 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.

What size subwoofer does an 11x22 room need?

Subwoofer size is less about this room's 242 sq ft and more about the output headroom you want; room size mainly changes where the 81 modes below 200 Hz fall. A room this size needs more sub output to reach the same level as a smaller one, and running two subs at different spots evens out the response between seats.

Why is bass boomy in one spot in an 11 by 22 ft room?

Here it comes down to this: two of its dimensions reinforce the same note near 51.2 Hz. That is a property of the room's shape, not your equipment, so treatment, not a better sub, is the fix.

What is the fastest fix for bass in an 11x22 room?

Corner bass traps come first, as thick as you can fit (6 to 12 in) plus a membrane trap tuned near 51.2 Hz, since that note's own quarter wavelength (about 5.5 ft) is too deep for any panel. After that, reposition your seat near 8.4 ft from the front wall and verify with REW below 161 Hz.

Similar room sizes

• 12x22 ft, 9 ft ceiling
• 11x22 ft, 8 ft ceiling