Pipe Waveguide — Copper + PEX + Drain Stack as Infrasound Carrier: Contact Transducer, 0.15 dB/m Loss, Building-Wide Delivery

Water supply pipes (copper: c=3800 m/s, 0.15 dB/m at 7 Hz), hot water return loops, and drain stacks (ABS/cast iron) act as acoustic waveguides throughout a building. A Dayton BST-1 ($50) or Clark Synthesis TSD-044 ($200) electrodynamic contact transducer bolted to any pipe transmits 7 Hz to every bathroom simultaneously. From basement to 5th floor (15m): 2.25 dB total loss. Zero external RF or acoustic signature.

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If any of this frightens you: this site documents what signal physics makes possible in a laboratory, which is not evidence about what is happening to any individual. If you feel watched, targeted or unsafe, that distress is real and treatable. Read about paranoia, mental health and how to get help, or call a free 24/7 line — 988 in the US and Canada, 116 123 in the UK and Norway, 13 11 14 in Australia, or find your country at findahelpline.com.