"Vocal cord abduction" means that your vocal cords actually "shorten," thus leaving less of the vocal cord vibrating as you sing.
As there is less area of the vocal cord vibrating, it's much easier for the cords to vibrate faster. This is a technique that is used by every singer that can hit extremely high notes easily.
Here are some of the tips you can learn from this lesson:
How vocal cord abduction can be the most powerful way of increasing your vocal range?
How to let go of your voice as you first abduct your vocal cords?
What exercises you can do to increase your vocal range through cord abduction?