From Computer World:
It’s long been known that secret messages can be included in music through techniques such as backmasking, but now a Polish researcher has developed an entirely new approach. By subtly varying the tempo of a particular type of dance music, he’s managed to encode information in a way that’s completely inaudible to human listeners.
StegIbiza is an algorithm for hiding information in a type of dance music known as Ibiza, which originates on the island by the same name in the western Mediterranean Sea. Ibiza music is characterized by its trance-like beat, and that’s what Krzysztof Szczypiorski, a professor at Poland’s Warsaw University of Technology, made use of.
To create his approach, Szczypiorski began by developing a sort of Morse code by which the dots and dashes that would represent letters are converted instead into a faster or slower tempo for a particular beat.
To prove his concept, he used Apple’s Logic X Pro music production software to create covers of five popular songs: “Lily was here” by David A. Stewart and Candy Dulfer; “Miracle” by Queen; “Rhythm is a dancer” by Snap!; “So what” by Miles Davis; and “You were the heart’s beat” by Andrzej Zaucha.