Ubuntu 16.04 does not play a startup / login sound in my laptop, but it’s easy to play a sound at login and customize the sound file by adding a new startup program using Startup Applications utility.

And below steps will show you how:

1. Launch Startup Applications utility from the Dash.

2. When it opens, click Add to add a new startup program and:

• Type any word in Name and Comment boxes.
• For the Command box, paste below line to play the default Gnome login sound:

  /usr/bin/canberra-gtk-play --id="desktop-login" --description="GNOME Login"

3. To play any other .ogg, .oga, or .wav sound at login, you can use paplay command in the Command box.

For example:

paplay /home/handbook/Audio/linux-startup.ogg

paplay /usr/share/sounds/purple/login.wav

After saved the changes, you’ll hear the sound at next login.