One of the most fascinating cases of early EVP research was demonstrated by the Italian medium, Marcello Bacci. Starting in 1974, over a period of about 20 years, Bacci gave public performances of his spirit communication technology to audiences in Grosseto, Italy. Audience members were given the chance to hear the voices of their deceased loved ones.

Bacci started out by using an old military radio that was used on naval ships but eventually moved on to a larger vacuum tube radio set with three loudspeakers, which he said provided better sound and clearer voices. Both of these radios were unmodified.

During the demonstration, he would then tune the radio to a part of the radio spectrum that was devoid of radio broadcasts. In a 2000 interview, he explained, "There is not a particular frequency. I can go all the way from left to right, and if the voices want, they come...