How our wave-based room simulation works
Most room-acoustics tools guess. We solve: below 200 Hz, we compute the actual standing waves inside your room's real 3D shape, then hand off to ray tracing above it.
What makes this different
A true 3D wave solve, not a shoebox formula
We compute your room's own standing waves on a grid of its real air volume, footprint, ceiling slope and furniture included.
A hard hand-over at 200 Hz
Below 200 Hz, sound behaves as standing waves. Above it, ray tracing takes over. Each method runs where it's actually accurate.
Industrial-grade eigensolvers
The same class of sparse eigenvalue solvers used in large scientific and engineering simulations extracts every mode up to 200 Hz.
Panels modeled as real hardware
A panel's absorption comes from its actual thickness, flow resistivity and air gap, run through an impedance model, not a rule of thumb.
See the whole pressure field
3D maps of pressure and particle velocity move through your entire room, not just one microphone point.
Two kinds of physics, one room
Sound in a room isn't one thing end to end. Below roughly 200 Hz, bass builds into standing waves shaped by every wall and corner. Above that, sound behaves more like a spray of particles bouncing around.
We run one solver for each regime, then join them at a single frequency. Wave physics governs everything below 200 Hz. Ray tracing governs everything at and above it.
Below 200 Hz: solving the waves themselves
Below 200 Hz, we don't approximate your room as a box. We divide its actual air volume into a grid of small cells, 15 cm on a side by default. Then we solve for how pressure resonates through that exact shape.
That grid resolves about eleven points across the shortest wavelength at 200 Hz. For very large rooms, we coarsen it automatically, down to about six points per wavelength, to keep the solve tractable.
The math itself is a Helmholtz eigenproblem. Room walls are treated as rigid. We solve directly for the frequencies and shapes of the room's own standing waves, the exact quantity a shoebox formula can only guess at.
Your actual room shape, not a textbook box
Real listening rooms are rarely rectangular. Ours can carry an L-shaped footprint, a wing or alcove, and a sloped or stepped ceiling. None of it gets flattened into an average box.
Furniture and cabinetry are carved out of the air volume as solid obstacles before the solve runs. A sofa or credenza genuinely displaces air and reshapes the modes around it.
How absorption and panels enter
The rigid-wall solve itself never changes with absorption. Instead, every mode gets its own damping factor, computed from how much of its pressure falls on absorbing surfaces.
A treatment panel's absorption doesn't come from a lookup table. It comes from a transfer-matrix model of the real panel build, thickness, flow resistivity and any air gap behind it.
What you can see
At the listening seat, you get a full frequency response from 20 to 200 Hz across 800 points, broken out by each speaker's own contribution.
Beyond the seat, you get every mode's frequency and damping, plus 3D maps of pressure and particle velocity through the whole room, the field porous absorbers actually work against.
Above 200 Hz: ray tracing
At and above 200 Hz, thousands of rays fire from each source, 10,000 by default. Each one bounces specularly off every surface, up to 60 times, losing energy to absorption and air along the way.
That decay curve runs through Schroeder backward integration to produce RT60 per band, from 40 Hz up to 10 kHz. A lighter 4,000-ray pass drives faster soundstage metrics: timing and level differences between your ears, lateral balance, how symmetric the decay is.
Why the hand-over sits at 200 Hz
Below the Schroeder frequency, typically 100 to 250 Hz in a small room, sound organizes into distinct, countable standing waves. Rays can't represent that: they carry no phase and no interference.
Above it, so many modes overlap that the field behaves statistically. Energy-based ray methods become both accurate and far cheaper there. We use a fixed 200 Hz cutoff rather than each room's own Schroeder frequency, a simplification we're upfront about.
What free calculators leave out
Most free room-mode calculators, including our own simple ones, use closed-form shoebox formulas. They assume a perfect rectangular box, no furniture, no openings. They don't know where you sit.
They can list mode frequencies, but not how strong a mode is at your seat, or how treatment changes it. Our free Room Acoustics Simulator and the full 3D room editor run the real wave solve on your actual room, and answer both.
How the optimizers use it
Placement and treatment optimizers don't guess either. They score candidate speaker positions against the simulated bass response at your seat, hunting for the flattest response below 200 Hz.
Treatment choices get scored against the ray-traced soundstage metrics, and against the biggest gain in decay, band by band, not one blanket RT60 number.
How we check it
The wave solve reproduces textbook rectangular-room mode frequencies within 1% for the first 20 modes. We check that automatically against a second, independent eigensolver on every change.
Ray-traced RT60 is sanity-checked against the Sabine formula. A public comparison against real in-room measurements is planned. It isn't published yet, and we'll link it here once it is.
Honest limits
Walls stay rigid in the wave solve. Absorption enters only as modal damping, not as a true boundary impedance. Rays reflect specularly, with no diffuse scattering modeled.
We don't model sound transmission through walls or structural vibration. A panel's effect on a mode's shape, not just its damping, is an approximation. A simulation is a prediction, not a measurement.
References
- Kuttruff, H. — Room Acoustics. 6th edition (2016). General reference for room-mode and reverberation theory.
- Everest, F. A. & Pohlmann, K. C. — Master Handbook of Acoustics. 7th edition (2015). General reference for room acoustics and reverberation.
- Cox, T. & D'Antonio, P. — Acoustic Absorbers and Diffusers. 3rd edition (2016). Reference for absorber design and the panel impedance model.
- Schroeder, M. R. — Die statistischen Parameter der Frequenzkurven von grossen Räumen. 1954. Origin of the statistical treatment of a room's frequency response above the Schroeder frequency, the basis for our 200 Hz hand-over.
- Miki, Y. — Acoustical properties of porous materials. Modifications of the Delany-Bazley model. Journal of the Acoustical Society of Japan (E) 11, 1 (1990). Basis for our panel absorption curves.
- Bass, H. E. et al. — Atmospheric absorption of sound. Journal of the Acoustical Society of America (1995). Basis for the air-absorption term in our ray-traced RT60 calculation.
- ISO 3382-1. Measurement of room acoustic parameters: reverberation time.
- ITU-R BS.1116-3. Listening environment recommendation for critical multichannel sound evaluation.
- Hernandez, V., Roman, J. E. & Tomas, A. — SLEPc. A scalable and flexible toolkit for the solution of eigenvalue problems. ACM Transactions on Mathematical Software 31, 3 (2005). Basis for the eigensolver behind our wave solve.
- Amestoy, P. R., Duff, I. S., L'Excellent, J.-Y. & Koster, J. — MUMPS. A fully asynchronous multifrontal solver using distributed dynamic scheduling. SIAM Journal on Matrix Analysis and Applications 23, 1 (2001). Basis for the shift-invert factorization in our wave solve.