How many reports of "ghost sightings" can be explained by the effects of infrasound, as opposed to craziness or fancy?

Further investigation led him to discover that the extraction fan was emitting a frequency of 18.98 Hz, very close to the resonant frequency of the eye… This was why he saw a ghostly figure — it was an optical illusion caused by his eyeballs resonating. The room was exactly half a wavelength in length, and the desk was in the centre, thus causing a standing wave which was detected by the foil.

It would be interesting to compare typical accounts of "ghost experiences" both before and after the widespread use of machinery likely to generate infrasound waves, to see if there was any trend towards describing symptoms similar to those caused by infrasound.

Of course, I'm discounting the possibility of real ghosts. It's preferable to the alternative. Math suggests that the development of intelligent life elsewhere in the universe is possible, or even probable. But I'd prefer not to accept the proposition that such intelligent life enjoys molesting our cows and going proctological on Billy-Jo-Bob. Similarly, to the extent I believe in an afterlife, I prefer not to contemplate that it entails moping about dank laboratories irritating obscure scientists. That's just depressing.

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