Representing Sound | Computer for GCSE/IGCSE - Year 11 PDF Download

Representing Sound

• Sound, in its essence, represents an analog signal that is captured and transformed into a digital format for computer processing.
• To convert sound into a digital form, a method known as sampling is employed. This technique entails measuring the sound wave at consistent intervals and converting these measurements into binary data.
• The quality of digital sound is influenced by the sample rate, which denotes the number of samples taken per second. A higher sample rate leads to a more precise representation of the original sound wave but also increases the digital sound file size.
• For instance, a standard CD-quality digital sound typically operates at a sample rate of 44.1 kHz, indicating that 44,100 samples are captured per second.
• Another critical factor is the sample resolution, which refers to the number of bits per sample. This determines the level of detail and accuracy of each sample.
• An increased sample resolution results in a more accurate representation of the sound wave, albeit at the cost of larger file sizes. For example, CD-quality digital sound commonly holds a sample resolution of 16 bits.
• Selecting the correct sample rate and resolution is vital, tailored to the specific needs of the digital sound application. For instance, high-quality music recordings may demand a higher sample rate and resolution compared to voice recordings for podcasts.
• Two examples of sound files are:
• MIDI (Musical Instrument Digital Interface):
  • MIDI is a file format that contains instructions on how a sound should be played.
  • It does not store the actual sounds but rather the data for playing them.
  • The information in MIDI files is generated using digital instruments.
  • Specifies details like which note to play, when to play and stop, note duration, volume, tempo, and instrument type.
  • Allows for editing individual notes for customization.
• MP3:
  • MP3 is a digital audio format used for recording sounds.
  • It is a compressed format (lossy) used for storing sound recordings.
  • Recorded using microphones to capture audio data.