Bugün öğrendim ki: İnfrasound dalgaları (20 Hz'nin altındaki frekanslarla) bozuk görüşe ve "hayalet" görme olasılığına yol açar. Ayrıca baş ağrısı, mide bulantısı, gece terörü ve uyku bozukluklarına da neden olabilir.

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Infrasound is sound below 20 Hz, lower than humans can perceive. but just because we don't consciously hear it, that doesn't mean we don't respond to it; In certain individuals, low-frequency sound can induce feelings of fear or dread or even depression. They may even be responsible for some ghost sightings, but we'll get to that in a second. What causes infrasound? Anything from earthquakes to meteors to ocean waves to fans to old, vibrating pipes in your attic. The occassional nuclear explosion, too (we actually use infrasound to detect them). Even [certain animals produce infrasound](http://en.wikipedia.org/wiki/Infrasound