What is “normalize” Package?

Adjust volume of audio files to a standard level
For more details: http://normalize.nongnu.org/

Installation

• Open Terminal by pressing command+space then type terminal and hit Enter key.
• Install homebrew first.

  ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null

• Install normalize.

  brew install normalize

Now, use normalize!