The false vocal cord means that’s the vestibular fold, which is located on the upper side, has no muscle actually but is able to move by itself.
It’s not possible to vocalize by the false vocal cord. If you have a large false vocal cord, for example if the false vocal cord condition is swollen or the erosion of vestibular folds, then production of vibrating sounds associated with the false vocal cord are mixed with sounds from the authentic vocal cords. This mixed sound is recongized and classified as a double sound or extreme low sound.
I’ve heard that you need to use the false vocal cord for making a death metal voice, I cannot confirm or deny this. However, I do understand and can explain the mechanics process of such a voice’s sound in that genre.
Note1:In the case of a death voice, you have to vibrate the sounds from the vocal cord in the soft tissues of the throat. These vibrations should travel to cover the vestibular fold, the epiglottis, the palatine uvula, and/or the tissues around the epipharynx.
Note2:For acquiring the death voice, you need flexible tissues in the throat and space in the area of the back of the tongue.
Note3:It is possible to move the vestibular fold, because it is located near the vocal fold and it is moved together in conjunction with the vocal cord muscles.