Fiber Cables as Microphones

Distributed acoustic sensing (DAS) — a laser‑pulse technique used to detect earthquakes — can pick up acoustic vibrations from speech on fiber optics; when those signals are fed into open AI transcription tools, intelligible, real‑time transcripts are possible from exposed or coiled urban 'dark fiber' at distances up to ~5 meters. Field tests show modest mitigation (20 cm of soil cover, straight vs. coiled geometry) but also suggest existing city fiber could be a privacy exposure vector if repurposed. — This reframes ordinary telecom infrastructure as a potential mass‑surveillance sensor, raising questions for privacy law, telecom operators, intelligence oversight, and urban infrastructure policy.