Electronic voice phenomena entered the paranormal literature through Friedrich Juergenson, a Swedish painter and documentary filmmaker who reported in 1959 that tape recordings he made of birdsong contained faint voices he could not account for, which he came to interpret as communications from the deceased, including, he believed, his own late mother.
Latvian-born psychologist Konstantin Raudive read Juergenson's work, began collaborating with him in 1964, and pursued the research intensively for the following decade, ultimately making and analysing over 100,000 recordings he believed contained discarnate voices, often in multiple languages he knew personally and attributed to specific deceased people he recognised.
Raudive published his findings in Breakthrough, translated into English in 1971, presenting transcripts and testimonials from scientists who had participated in some of his recording sessions, and the book made EVP a recognised, if marginal, claim within the wider survival-of-death literature, later extended by other researchers into more elaborate "instrumental transcommunication" setups using radios, televisions, and eventually computers rather than simple tape recorders.