Learn in the textbookDigital Representation of Audio and File Formats
DefinitionMIDI (Musical Instrument Digital Interface) is a standard for passing performance information (演奏情報) between electronic instruments and computers: not the sound waveform, but which note to play, when, and how strongly.
ExplanationBecause it sends only instructions and no sound itself, its data size is very small for the length of a piece. The actual sound is produced by the receiver's sound source (a device or software that generates sound) following the performance information, so the same data sounds different on a different sound source. A waveform itself, such as a recorded human voice, cannot be expressed as MIDI performance information.
AnalogyIt is like handing over sheet music rather than a recording: the same score sounds different depending on who plays it and on what instrument.
Memory hookThe last word of its full name is Interface. It began as an agreement for connecting one instrument to another.