Musical Instrument Digital Interface: a specification that standardises the interface between computers and digital devices that simulate musical instruments. Rather than transmit bulky digitised sound samples, a computer generates music on a MIDI synthesiser by sending it commands just a few bytes in length. These contain all the information a sound board needs to reproduce the desired sound – the type of instrument, the pitch, duration, volume, attack, decay, etc. are all specified by the protocol. Each channel of a MIDI synthesiser corresponds to a different instrument, or “voice”. Programming several channels simultaneously produces symphonic sound.
