Introduction To Digital, Analog and MIDI Audio

 

Sound:

 

Sound has 3 Stages of Development:

 

 

  1. Creation
    • The vibrations have to be set in motion.
    • Can be done mechanically (physical movement of air), electrically (generation of electrical waves), digitally. (digital memory of sound waves)
  2. Transfer To Output
    • Vibrations are amplified and sent to output.
    • Can be done mechanically, via analog signal (electrical signal) or through a D/A converter (Digital to Analog Converter.
  3. Output
    • Vibrations must be turned into sound waves which our ears can detect.
    • Must be mechanical since air must be moved for our ear drum to detect the sound.

 

4 Types of Sound Creation Devices:

 

 

  1. Acoustic Devices
    • Creation is mechanical.
    • Transfer is mechanical
    • Output is mechanical
      • Eg. Any "acoustic" instrument such as a guitar where the vibration is created by the physical movement of the string, the sound is amplified and modified by the shape of the guitar sound box, and the sound is output to our ear.
  2. Electric Devices
    • Creation is mechanical
    • Transfer is analog
    • Output is mechanical
      • Eg. Any "electric" instrument such as an "electric guitar" where the vibration is created by the physical movement of the string, the transfer is done by an "electric" pickup which transfers the sound into an electrical signal which is amplified and modified, and the output is sent from a speaker which physically pushes the air.
  3. Electronic Devices
    • Creation is analog.
    • Transfer is analog
    • Output is mechanical.
      • Eg. An "analog synthesizer" which uses electrical oscillators to generate the vibrations, the transfer is done by an amplifier and/ or other electrical modifiers, and the output is again a speaker or headphone which physically pushes the air.
  4. Digital Devices
    • Creation is actually the digital storage of a sound source.
    • Transfer is done by a D/A (Digital to Analog) converter which converts digital information into an analog signal which is modified and amplified.
    • Output is mechanical.
      • Eg. A "digital" synthesizer which stores digital "samples" of sounds, uses a D/A converter to change it the sounds to an analog signal which it modifies and amplifies, and is output through a speaker or headphone which physically pushes the air.