Sentence:  But creaky or <WSD>laryngealized</WSD> quality throughout whole stretches of very low-pitched speech characterize boredom, reluctance [etc.] Children typically <WSD>laryngealize</WSD> their voice for coaxing adults. 
Meaning of the word marked with <WSD> tags:  To modify (a pronunciation or a sound) by constricting the larynx.