History: What is reverberation?

What is reverberation?

• Reverberation is a sound changing module that plays the sound source more than once at different times.
  Sort of, but this describes delay.
• Reverberation is a sound modifying module that helps to balance the frequencies of the incoming signal.
  That would be an equalizer.
• Reverberation is a synthetic phenomenon where a sound source reflects off of surfaces, creating a sense of color.
  Reverberation is real.
• Reverberation is a natural phenomenon where a sound source reflects off of surfaces, creating a sense of space.
  Correct!