infrasonic room sweep

every room has resonant frequencies called room modes — standing waves that reinforce or cancel depending on where you are. this tool sweeps 18–320 hz through your speakers over 18 seconds. the microphone captures how the room responds. peaks in the response reveal physical dimensions: a mode at 50 hz implies a ~3.4 m surface.

below ~20 hz is infrasonic — not heard but felt as pressure. most laptop speakers won't reproduce it, but subwoofers and large monitors will.

• your room is an acoustic filter. the reflections from walls, floor, and ceiling create resonances that color every sound you hear. recording studios spend thousands treating these modes. now you can see yours.
• dimensions from frequency. the first axial mode of a room follows f = c / (2L). a clear peak at 57 hz means a surface ~3 m away. at 86 hz, ~2 m. the browser just became a tape measure.
• infrasound is real. 1–20 hz pressure waves from hvac, traffic, and large machinery cause the “sick building” effect: unease, dizziness, concentration loss. they bypass conscious hearing and act directly on the vestibular system.
• listening to a room without moving. this is the basis of acoustic tomography: a single sweep from a fixed point can characterize an entire enclosed space.