They pointed out that the voices sometimes sounded like snatches of conversation from foreign radio stations picked up by Raudive's tape recorder. One researcher found that one of the most impressive "voice texts" appeared to be a burst of 37 German words from an Easter Sunday radio broadcast. ...
Psychologists quickly recognised EVP – sometimes referred to as "Rorschach audio", after the test in which subjects read their own interpretation of inkblot images – as just another example of the brain's penchant for making sense even of the patently senseless.
Known as pareidolia, it lies behind such bizarre claims as the decade-old toasted cheese sandwich said to bear an image of the Virgin Mary, which sold for $28,000 on eBay in November. In its search for order, the brain simply cajoles random patterns into making sense – sometimes at the price of rationality.
Linguists have done experiments on the brain's "categorical" perception of indistinct sounds for decades. This phenomemon is one of the foundations of modern phonetic theory; based on your learned language's sound system, your brain is more likely to "hear" sounds that fit into the phonetic and phonological rules you've internalized. It will do work to make noise fit into those sound categories.