HVAC Duct Infrasound Delivery — Fan Speed Modulation + Room Mode Excitation + Smart BMS Attack Vector

Sheet metal HVAC ducts transmit sound 20× more efficiently than open air. Attacker modulates rooftop fan speed via smart BMS access to vary infrasound frequency 50–80 Hz matching room axial modes. Room mode at duct opening +12 dB. All rooms connected to the same duct system receive simultaneous signal. Axial modes, Sabine reverberation time, duct pressure node mapping, and defense via duct-mounted passive absorber tuned to 7 Hz.

Scene 54 of 109 in the StopBeingParanoid interactive 3D research collection. Requires JavaScript and WebGL2 for the interactive visualisation.

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