Lesson 4.5.6.8

4.5.6.8 Musical Instrument Digital Interface (MIDI) Quiz: AQA Computer Science, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.5.6.8, Musical Instrument Digital Interface (MIDI): 20 multiple choice questions for the AQA Computer Science (7517), Unit 5: Fundamentals of data representation, written with Revision Ninja.

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The 20 questions

  1. What does MIDI stand for?

    • Media Interface for Digital Instruments
    • Multi-channel Integrated Digital Image
    • Musical Instrument Digital Interface
    • Musical Input Data Index

  2. What does a MIDI file store in place of audio samples?

    • Event messages describing actions, such as notes being played
    • Individual sound samples of every note, recorded at a fixed rate for the whole performance
    • Pixel values of a musical score, one value for each dot on the printed page of music
    • Analogue voltage levels from instruments, sent as a continuous signal down a cable

  3. Which of these is a MIDI event message type?

    • Sample rate
    • Checksum
    • Note on
    • Pixel fill

  4. What is an advantage of MIDI files over recorded audio for music?

    • They include a full recording of the performer's voice
    • They need no playback device
    • They always sound identical on every instrument
    • They are small, since they store note events rather than waveforms

  5. Why can a MIDI file sound different on different synthesisers?

    • MIDI files are analogue, so the sound they produce varies with the voltage of each device
    • MIDI files contain a full recording of each instrument, which every device plays back unchanged
    • MIDI files always store the exact timbre of each sound, so every device plays it identically
    • The file describes notes, so each device's own instrument sounds decide how they are heard

  6. What information does a MIDI note-on event typically include?

    • The duration of the whole file in bytes, which is repeated in every event in the file
    • The pixel colour of the note, which is used to show the note on a screen display
    • The note number and how hard the note is struck, called velocity
    • The sampling rate of the sound, which sets how many samples are used to play the note

  7. How would you best describe MIDI?

    • A standard protocol for sending musical performance data between devices
    • A compressed audio format for streaming music over the internet at a fixed bit rate
    • A sampling rate standard for CDs, which fixes the number of samples in each second
    • A video codec for music videos, which stores the picture and the sound together

  8. Which MIDI note number is middle C, which is 60, in 7-bit binary?

    • 0111100
    • 0110100
    • 1111100
    • 0111000

  9. How many distinct MIDI note numbers can be represented with 7 bits?

    • 127
    • 256
    • 120
    • 128

  10. A MIDI file uses 3 bytes per note event and contains 1000 note events. What is its size?

    • 1000 bytes
    • 30,000 bytes
    • 3000 bytes
    • 300 bytes

  11. A melody of 400 notes has a note-on and a note-off event for each note, with 3 bytes per event. What is the total size?

    • 3600 bytes
    • 800 bytes
    • 1200 bytes
    • 2400 bytes

  12. Four bits are used to store a MIDI channel number. How many channels can be addressed?

    • 8
    • 32
    • 16
    • 4

  13. A song's CD-quality stereo audio takes about 32 MB for three minutes. A MIDI version has 3000 events at 3 bytes each. What is the difference in scale?

    • The MIDI version is about 9000 bytes, far smaller than the audio
    • The MIDI version is about 9 MB, the same size as the audio
    • The MIDI version is about 900 bytes, too small to play
    • The MIDI version is about 90,000 bytes, the same as the audio

  14. How many bits are needed to store one MIDI note number from 0 to 127?

    • 7
    • 6
    • 128
    • 8

  15. Two notes sound at the same time in a MIDI sequence. How are they represented?

    • As two separate note-on events
    • As a checksum of the two notes
    • As one combined sound sample
    • As a single pixel of colour

  16. Why is MIDI described as music data rather than sound?

    • It stores only the lyrics of songs, with the melody added later by the playback device
    • It stores instructions about notes, timing and control, not the sound wave itself
    • It stores sound as images of the waveform, drawn as a graph of the amplitude over time
    • It stores sound waves at a very low sampling rate, so the audio is kept small in size

  17. A composer wants a file that is easy to edit and transpose. Which format is best?

    • MIDI, since individual note events can be changed without re-recording any audio
    • A bitmap score, since notes are stored as pixels that can be moved around the page
    • A lossy image format, since it is easy to edit and keeps the notes in their original positions
    • WAV, since every sample must be re-recorded to change a note, which makes the file easy to edit

  18. Why would a MIDI file be unsuitable for recording a singer's voice?

    • MIDI stores note events, not the varied waveform of a voice, so the voice cannot be reproduced
    • MIDI can store voices only at 8 kHz, which is too low for a clear recording of speech
    • MIDI requires an ADC to store any sound, so a voice cannot be recorded in a MIDI file
    • MIDI files are always stored as images, so a voice would have to be drawn as pixels

  19. A MIDI keyboard sends a note-on event with velocity 100, and a synthesiser plays it louder than a velocity of 40. What does this show?

    • Velocity sets the sampling rate of the note, so a higher value means more samples per second
    • Velocity is a pixel colour that changes the sound by altering the shade of the note on screen
    • Velocity is an ADC step that converts the note from a voltage into a number on the scale
    • Velocity is a data value that controls how loudly the note is played

  20. Which statement best compares MIDI and digital audio for storage?

    • Digital audio is always smaller, since its samples are compressed by default before they are stored
    • MIDI stores events and is much smaller, while digital audio stores every sample and can capture any sound
    • MIDI and digital audio store identical data at different sizes, so either can capture the same sound
    • MIDI stores every sample, so it is larger but more faithful to the original performance recorded

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