MIDI is a serial control protocol carrying numbered performance messages, never audio waveforms

MIDI (Musical Instrument Digital Interface) is a digital protocol for transmitting performance data between controllers (devices that output MIDI) and sound modules (devices that produce or modify sound). The critical distinction: MIDI messages describe what to play but contain no audio — the waveform resides in the receiving module, so the same message (‘middle C at velocity 80’) sounds different on every device that receives it. Complaints that a MIDI recording ‘sounds too digital’ are therefore about the synthesizer, not MIDI. MIDI uses up to 16 independent channels per port, so one connection can address 16 instruments. Performance data is expressed as 7-bit integers (0–127). The three-byte Note On format is [status = 144 + channel] [note number 0–127] [velocity 0–127]; velocity is the parameter distinguishing a soft note from a loud one. Program Change selects between timbres stored in the receiving module.

Examples

Middle C Note On on channel 1: bytes 144 60 120. A master keyboard with no internal sounds transmits MIDI only, so it makes no sound unplugged from a synth; a keyboard synthesizer has an internal sound module that responds to its own MIDI output.

Assessment

A student asks why their MIDI keyboard makes no sound unplugged from a synth — explain the MIDI model in three sentences, then write the three bytes for a middle C Note On at velocity 100 on channel 3. Also explain why a ‘too digital’ complaint targets the synthesizer, not MIDI, and which parameter distinguishes a soft from a loud note.