Storing sound

• Digitised sound


  Thousands of numbers output by the analogue-to-digital converter
• Storing digitised sound


  1. Send string of numbers to digital-to-analogue converter and loudspeaker

  2. Send string of numbers to computer for storage
• Digital sound samples in their raw form occupy a substantial amount of memory
• Activity 3.12 (practical)


  1. Run Audacity and load the sound file

  2. Select the whole sound and determine the duration in seconds

  3. Calculate the number of samples based on the sampling rate

  4. Change the format to display the duration in samples

  5. Locate the file and note the size in bytes

  6. Calculate the expected file size based on 2 bytes per sample and 44 bytes for format information
• The sound file is exactly 4 seconds long with a sampling rate of 44,100 samples per second, so the number of samples is 176,400
• If each sample requires 2 bytes of storage, and an additional 44 bytes are needed for format information, the file size should be 352,844 bytes