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Knowledge organisers / Data Storage: Sound

Sound: How sound can be sampled and stored in digital form

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Knowledge organiser

Data Storage: Sound

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What you need to know

Sound is analogue — it is a continuous wave. Computers cannot store continuous waves, so they take regular 'snapshots' (samples) of the sound wave's amplitude at set intervals. Each sample is stored as a binary number.

Key points

  • Definition:Analogue Sound: sound represented as a continuous wave that varies smoothly over time.
  • Definition:Sample: a measurement of the amplitude (height) of a sound wave at a specific point in time, stored as a binary number.
  • Definition:Sampling Rate: the number of samples taken per second, measured in hertz (Hz). 1 Hz = 1 sample per second.
  • Definition:Bit Depth (Sound): the number of bits used to store the amplitude value of each sound sample when converting analogue sound into digital form. More bits = more precise amplitude values.
  • Sound is analogue (continuous); computers store it digitally (discrete samples).
  • Exam Tip:A higher sampling rate captures MORE samples per second, creating a more accurate representation of the original sound wave.
  • Exam Tip:Sound sampling measures the AMPLITUDE (height) of the wave at regular intervals. It does NOT measure the frequency of the wave. This is a VERY common exam mistake.
  • Common Mistake:Saying 'the frequency of the wave is measured'. In sound, frequency relates to pitch. What is SAMPLED is the AMPLITUDE at set intervals.
  • Each sample is stored as a binary number. These binary numbers are stored sequentially to reconstruct the sound during playback.