Hello Locrian (love that name as it is one of the more unusual modes of the major scale!),
According to Yogani's AYP book, Ujjayi (partially holding the epiglottis while exhaling in pranayama) creates additional pressure in the lungs and pranic pressure throughout the nervous system. It also creates a fine vibration deep in the throat that assists in purifying and opening the neurobiology in the chest throat and head.
With Peace and Respect,
Paul