A small sample-set study of young American women to be published in Journal of Voice found a high incidence of "vocal fry," a form of low-register speech once classed as a speech disorder and thought to cause damage to the vocal chords. Vocal fry occurs when speakers drop into the lowest register and sort-of gargle their words (here's an example MP3).
More than two-thirds of the research subjects used vocal fry during their readings, the researchers will report in a future issue of the Journal of Voice. The distinct vibrations weren't continuous. Rather, they arose most often at the ends of sentences. The patterns were "normal" variations, says co-author and speech scientist Nassima Abdelli-Beruh of LIU, because the women rarely slipped into vocal fry during sustained vowel tests—prolonged holding of vowels such as 'aaa' and 'ooo'—a classic way to assess voice quality and probe for possible disorders. Abdelli-Beruh says the creak is unlikely to damage vocal chords because speakers didn't creak continuously or even at the end of every sentence.
The study is the first to quantify the prevalence of vocal fry in normal speech, although other researchers have noted the pattern. The group is also the first to verify that American women are much more likely to exhibit the behavior than men, as its yet-unpublished data show that male college-age students don't use the creaky voice. The team's next steps will attempt to find out when this habit started—and if it is indeed a budding trend.
The researchers also plan to test students in high schools and middle schools to learn why young women creak when they speak. "Young students tend to use it when they get together," Abdelli-Beruh says. "Maybe this is a social link between members of a group."