taking one song and using the audio frequency to modulate the frequencies of another song. then I play both songs mixed or mashed together then I go back and play the frequency modulations and the songs all together .,, totally mixed like that,..

https://www.youtube.com/watch?v=lh5UT-IqjmM the video

https://www.youtube.com/watch?v=r9u-mt5RQyk