MacOS – Location of OS X Volume Change Feedback Sound File

It looks like for macOS Sierra you simply need to change the Alert Sound under the Sound System Preferences (System Preferences > Sound > Sound Effects).

It can be done, although you need to find the Mavericks volume feedback sound file. The filename is "volume.aiff" and (for both Mavericks and Yosemite) it is located in: /System/Library/LoginPlugins/BezelServices.loginPlugin/Contents/Resources

Find the Mavericks volume feedback sound file and put it on your Desktop for easy access.

Open the Terminal and navigate to the folder containing the sound file:

cd /System/Library/LoginPlugins/BezelServices.loginPlugin/Contents/Resources

Create a backup of the original file in case you want to reverse the changes:

sudo cp volume.aiff volume.aiff.bak

Provide the password when prompted.

Now copy in the Mavericks sound file placed on your Desktop:

sudo cp ~/Desktop/volume.aiff ./

Restart