How do I trigger an action once from global variable?

I have a project where I need to trigger a sound effect once when the timer variable = zero. But When I did this the audio clip is looping, but I need it just to play when the variable initially = zero. Any ideas?

Trigger once while true

you probably want trigger once while true

This is from the system reference in the manual

Turn an ordinary event (which is tested every tick) in to a trigger. For example, if an event plays a sound when lives equals 0, normally this event runs every tick. This plays about 60 sounds a second and would sound pretty bad. Adding Trigger once while true after the other conditions makes the event run just once when it first becomes true. This makes the previous example only play a sound once the first time your lives reaches 0. It must be the last condition in an event.

Thank You so Much! It worked perfectly!