This addon reminds you about the expiration of the buffs you decide to track.
You can choose which buffs to track and the addon will assign a different sound to each one of them till a max of 10.
While in combat when one of your tracked buff it's expiring the addon will "sound" and spam in your chat window.
Saundo is actually a reminder that can be used with each kind of buff active on the player.
Type /saundo to view a description of available slash commands.