First of all, you need to download and install the "PMCO - Pilot Monitoring Callouts" tool by Nils Unger available here:
These files have been recorded and mixed to make the ambiance more immersive in your FSLabs A3XX cockpit and to make you seated beside a man or a woman first officer.
You have the choice between several accents according to the airline you want to fly. These files has been created as text to speech voice.
Hope you will enjoy them!