Why is the bass uneven in my room?

What this is telling you

A room reinforces any frequency whose half-wavelength fits neatly between two surfaces, and cancels it at the midpoint. That is why bass can be boomy in one chair and thin two feet away, and why the same speakers sound different in a different room.

f = (c / 2) × √((p/L)² + (q/W)² + (r/H)²) with c = 343 m/s. Axial modes have one of p, q, r non-zero and are much the strongest — those are the ones worth acting on.

What actually helps

• Move the seat before you buy anything. The worst place to sit is exactly halfway down the room, where the strongest length mode cancels. A foot or two makes a bigger difference than any component change.
• Do not put the speakers and the seat at the same fraction of the room. Both at a third works well; both at a half is the worst case.
• Bass trapping goes in corners, where every mode has maximum pressure.
• A subwoofer can be moved independently of the mains, which is precisely why one well-placed sub often beats bigger speakers.

Where this stops being true

Above the Schroeder frequency shown above, modes are packed so closely together that they stop behaving as separate resonances and the room behaves statistically instead. And a real room is not a sealed box: doorways, plasterboard and open-plan spaces shift these frequencies and blur them. Treat the list as where to look, not as a measurement.

Once placement is sorted, the SPL calculator tells you how much power the room and distance actually ask for.