Barely cutting through the din of radio white noise, a woman's voice hypnotically chants the numbers 1-6-8 between larger sets of numbers. She recites them slowly, clearly, with eerie detachment. In another transmission, probably from Sweden, a female voice intersperses her series of mysterious strings of digits with interludes from what sounds like a music box. Elsewhere, a Cuban man sings his series of seemingly random digits.

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One notable exception is stations that seem to be broadcasting from Israel, he says. "There seems to definitely be a pattern of stations from Israel. They tend to become more active when there are events happening over there."

Taken together, these recordings possess almost a musical quality. It's collage art made from sound, what with the wide variety of white-noise textures, the almost ghostly delivery of the numbers, the fragments of music and other broadcasts, the minimal melodic patterns of the recitals, and the allure of their unknown origin.