Room Modes in a 15x22 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 and 15 ft width both resonate near 75.0 and 150.0 Hz, so 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.
• Your 15 ft width and 9 ft ceiling height both resonate at 187.6 Hz, so bass at that note will be much louder than its neighbours.
• Between 25.6 Hz and 37.5 Hz there are no modes at all, so notes in that 11.9 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 : 1.67 : 2.44) fall inside the Bolt area, the range of room ratios that spreads modes most evenly.
• Below about 138 Hz (the Schroeder frequency) individual modes shape the sound; above it, reflections and reverb matter more.

Your 22 ft length and 15 ft width share a mode near 75.0 Hz. When two dimensions resonate at the same note, their boosts add up, so that note stacks on top of itself and comes out noticeably louder than the bass around it.

If you use this room for movies, that stacked note tends to show up as boom on specific low-frequency effects rather than an even rumble. If it is a music or mixing room, that same spot makes some bass notes read louder on playback than they actually are on the recording, which makes mixing bass by ear risky here.

Height, width and length work out to 1 : 1.67 : 2.44, which lands inside the Bolt area. Rooms with that proportion usually need less correction than a room shaped like a cube or a hallway.

How to fix it, in order

1. Treat the four floor-to-ceiling corners first; they are common to every mode this room produces, and your ceiling height is part of the problem.
2. Full absorption at 75.0 Hz would take about 3.8 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. Move your listening position off-center along the 22 ft length; roughly 8.4 ft from the front wall (38% back) is a common starting spot before fine-tuning.
4. Walk the subwoofer around the front of the room while playing a bass-heavy track and listen from your seat: corner placement is loudest but least even, and a second sub or an off-corner spot often fills in this room’s weak points.
5. Once traps are in, measure with REW from the listening position. Focus on frequencies below 138 Hz (this room's Schroeder frequency); that is where individual modes, not general reverb, are running the show.

Every mode below 200 Hz

This room has 107 modes below 200 Hz, 15 axial, 52 tangential and 40 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 15x22 rooms

Is a 15 by 22 ft room good for a music room or home theater?

This size is workable for a dedicated home theater or media room, but its modal score of 42/100 is low, driven by the fact that two of its dimensions reinforce the same note near 75.0 Hz. Go in expecting a serious treatment plan.

What is the best corner for bass traps in a 15x22 room?

The four vertical corners first. Full absorption at 75.0 Hz would take roughly 3.8 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 a 15x22 room need?

Subwoofer size is less about this room's 330 sq ft and more about the output headroom you want; room size mainly changes where the 107 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 a 15 by 22 ft room?

Here it comes down to this: two of its dimensions reinforce the same note near 75.0 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 a 15x22 room?

Corner bass traps come first, as thick as you can fit (6 to 12 in) plus a membrane trap tuned near 75.0 Hz, since that note's own quarter wavelength (about 3.8 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 138 Hz.

Similar room sizes

• 14x22 ft, 9 ft ceiling
• 16x22 ft, 9 ft ceiling
• 15x22 ft, 8 ft ceiling