What is "electrocardiophone"

An electrocardiophone or cardiophone is a musical instrument or diagnostic tool which uses heart waves (measured in the same way as an ECG) to generate or modulate sounds.

James Fung, Ariel Garten, and Steve Mann (~2003) have created a wide variety of underwater biophone systems that use physiological signals to control different musical variables in an intricate way, as well as to actually generate sounds, including underwater ECG and EEG concerts.

The electrocardiophone is a quintephone in the sense that it creates sound from the "5th classical element" (i.e. from beyond the world of matter).