In this tutorial, you’ll learn how to batch normalize audio on MacOS with the cross-platform command line utility SoX (Sound Exchange).
Download & Install SoX
To install SoX, you’ll first need to download and install a package manager for MacOS called Homebrew.
Navigate to ~/Applications/Utilities, and click on the Terminal app. Copy and paste the snippet below into the Terminal window.
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)
Press Enter to start the installation process.
Press Enter again to continue the installation process. The script will ask for your administrator password to complete the installation.
When the installation is finished, use the snippet below to install SoX.
brew install sox
Next, use Finder to create a folder on your desktop, and place the audio files you want to normalize into the folder. I’ve named my folder 2convert. Create a second folder in the 2convert folder called converted.
Navigate back to Terminal, and use the snippet below to navigate to your newly created 2convert folder.
Finally, use the following snippet to normalize all audio files in the 2convert folder to -0.1dB.
for file in *.wav; do sox $file — norm=-0.1 converted/$(basename $file) -V; done
The normalized files can be found in the converted folder.