Leeneia, the program (such as EZPIANO and Noteworthy) is what converts the file to sound. EZPIANO won't read Noteworthy files, and Noteworthy won't read EZPIANO files. It's as if the two different types of files are written in different languages. If both of them understand "MIDI language," that's how you can switch them over.

Is there a way to open the files with EZPIANO and save (or export) them as MIDI files?