Change default alert sound from terminal in Mac OSX
Solution 1:
It looks like for macOS Sierra you simply need to change the Alert Sound under the Sound System Preferences (System Preferences > Sound > Sound Effects).
Solution 2:
In Sierra:
defaults write .GlobalPreferences com.apple.sound.beep.sound /System/Library/Sounds/Submarine.aiff
Solution 3:
I don't know how to make Terminal use a different alert sound, but if others search for how to change the OS X-wide alert sound from a script, change the com.apple.sound.beep.sound
key in the com.apple.systemsound
domain:
defaults write com.apple.systemsound com.apple.sound.beep.sound /System/Library/Sounds/Frog.aiff