The Wikipedia article on infrasound (
Infrasound - Wikipedia) says much the same thing about the effects on humans and also mentions Tandy's
The Ghost in the Machine, as well as:
quote:
Infrasound has been known to cause feelings of awe or fear in humans. Since it is not consciously perceived, it can make people feel vaguely that supernatural events are taking place.
Some film soundtracks make use of infrasound to produce unease or disorientation in the audience. Irrversible is one such movie.
But neither link mentioned harmonics. Most, if not all, naturally occurring sounds are not pure, but rather have complex waveforms produced by combining a series of pure tones of different intensities. The frequency of each harmonic is some multiple of the fundamental frequency and the intensity (sound volume) tends to be strongest at the fundamental frequency and decrease as you go up through the harmonics, though that's not always the case. The intensities of the harmonics of a complex sound wave can by worked out by Fourier analysis and displayed on a graph called a "power spectrum". In music, each instrument produces different harmonics which accounts for their
timbre, which is why a violin sounding at a particular pitch sounds different from a flute sounding at the exact same pitch.
My point is that while an infrasound may be at a pitch that is too low for us to hear, it is also a complex sound that has harmonics. It just seems to me that some of those harmonics could very well be audible, which would account for hearing "voices".
Edited by dwise1, : had forgotten to add the URL
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