According to Marissa Fessenden, "'Vocal Fry' Creeping into U.S. Speech", Science Now 12/9/2011:
A curious vocal pattern has crept into the speech of young adult women who speak American English: low, creaky vibrations, also called vocal fry. Pop singers, such as Britney Spears, slip vocal fry into their music as a way to reach low notes and add style. Now, a new study of young women in New York state shows that the same guttural vibration—once considered a speech disorder—has become a language fad.
This story has been picked up elsewhere, e.g. Cory Doctorow, "Deep-voiced 'vocal fry' thought to be creeping into American women's speech", BoingBoing 12/11/2011; Ben Flanagan, "Vocal Fry a new language fad mainly among college females", AI.com 12/12/2011; Meredith Engel, "Vocal fry: Your creaky throat noises are now an actual scientific trend", Jezebel 12/12/2011; "‘Vocal Fry’ Is the Hot New Linguistic Fad Among Women", Gawker 12/12/2011; Melissa Dahl, "More college women speak in creaks, thanks to pop stars", MSNBC 12/12/2011.
It's nice to see a piece of phonetics research getting this kind of play. But Fessenden's take on this story will be surprising to those who have looked at a few pitch contours — these "low creaky vibrations" have been common since forever. And moderate use, especially at the ends of phrases, has never been considered a speech disorder.
Puzzlement increases after reading the cited paper.
The point of the paper (Lesley Wolk, Nassima B. Abdelli-Beruh, and Dianne Slavin, "Habitual Use of Vocal Fry in Young Adult Female Speakers", Journal of Voice, in press) is to quantify how common this phenomenon is, in one particular population of young adult American women:
The purpose of this study was to examine the use of vocal fry in young adult Standard American-English (SAE) speakers. This was a preliminary attempt (1) to determine the prevalence of the use of this register in young adult college-aged American speakers and (2) to describe the acoustic characteristics of vocal fry in these speakers. Subjects were 34 female college students. They were native SAE speakers aged 18–25 years. Data collection procedures included high quality recordings of two speaking conditions, (1) sustained isolated vowel /a/ and (2) sentence reading task. Data analyses included both perceptual and acoustic evaluations. Results showed that approximately two-thirds of this population used vocal fry and that it was most likely to occur at the end of sentences. In addition, statistically significant differences between vocal fry and normal register were found for mean F0 minimum, F0 maximum, F0 range, and jitter local. Preliminary findings were taken to suggest that use of the vocal fry register may be common in some adult SAE speakers.
The research reported in this publication doesn't raise the issue of changes over time, or even of differences between males and females. In fact, the authors cite a couple of 40-year-old papers by Harry Hollien and others ("On the nature of vocal fry", J Speech Hear Res. 1966; "Vocal fry as a phonational register", J Speech Hear Res. 1968) to the effect that "speakers without vocal pathology can selectively use glottal fry in connected speech".
In the Science Now article, Fessenden interviewed Pat Keating about this, and got a sensible answer:
Linguist Patricia Keating of the University of California, Los Angeles, agrees with Abdelli-Beruh's statement that creaking at the end of a sentence is normal for many speakers. "There are languages that use creak as part of the phonemic system," she says. "The chances of it leading to vocal damage are very minimal."
The small number of subjects and the limited geographic focus of the study make these findings very specific, Keating says. But she notes that speech researchers suspect the vibrational trend is widespread in the United States. "I think there are generational differences," she says. "But it is common to mark the end of sentences [with vocal fry]. If the pitch falls, you get creak."
A similarly sensible perspective is presented in a quote from one of the study's authors:
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.
The anecdotal phonetic folk-wisdom about this phenomenon agrees that it's commoner (or at least more salient) among women than among men, and may be commoner among younger speakers. So it's entirely reasonable that Wolk et al. report some unpublished evidence on differences between female and male students, and that they plan to study changes over time:
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.
But it's important to keep in mind that this kind of irregular or chaotic oscillation is a more-or-less inevitable feature of physical systems like those involved in human voiced speech (see e.g. Jiang and Zhang, "Chaotic vibration induced by turbulent noise in a two-mass model of vocal folds", J. Acoust. Soc. Am. Volume 112(5) 2002). So I'd be very surprised to learn that there are any speech communities where vocal fry is not sometimes found in normal, non-pathological speech patterns — and especially in low-frequency regions at the end of phrases, where the controlling parameters of vocal-cord tension and subglottal pressure are changing rapidly.
As a small piece of evidence that this phenomenon has been common in American speech for some time, I took a look at a few sentences from the "TIMIT Acoustic-Phonetic Continuous Speech Corpus", recorded in 1986. This collection includes sentences read by 630 male and female speakers from 8 major dialect regions of the U.S. One of the two "calibration sentences" read by all 630 speakers was "She had your dark suit in greasy wash water all year".
The very first female speaker (according to the collating order of the speech-file pathnames – TEST/DR1/FAKS0/SA1.wav, if you're following along at home) shows clear vocal fry at the end of this calibration sentence:
(The display above shows the waveform and spectrogram for the final word "year".)
This woman was born in 1957.
I had to look at four male speakers' readings of this same sentence to find an equally-clear example of phrase-final irregular voicing (TEST/DR1/MRJO0/SA1.wav):
This man was born in 1951.
I don't have time to do a fuller examination this morning, but this tiny bit of evidence is certainly consistent with the traditional view that vocal fry has long been a common feature of sentence-final low pitches in American English, and that it's commoner among female speakers than among male speakers. Whether there's a generational effect (which could be due to life-cycle effects or to some overall cultural change) remains to be seen.
It may well be true that there's cultural variation in the prevalence of vocal fry — certainly there are languages where the related phenomenon of "creaky voice" is phonemic, as Pat Keating observed. There's plenty of evidence out there to look at, in the form of recordings across time and space, and I look forward to seeing the results when they emerge.
It's too bad, though, that Science Now wrote the story as if this research had already been done!
Update — Some evidence of culturally-modulated deployment of creaky voice can be found in Carmen Fought's 2003 book Chicano English in Context (p. 78):
A final suprasegmental feature that is very characteristic of CE speakers in the Los Angeles community is creaky voice. This feature seems clearly to be an example of something that comes out of contact with the local Anglo dialect, where creaky voice is extremely prominent. [...] Helena, a young Anglo speaker that I interviewed, seems to end almost every sentence with a stretch of extreme creaky voice. [...] The CE speakers use this feature very frequently as well. Though I found it among male and female speakers, it seems to be more common for women, both among Anglo and Latina speakers. Interestingly, Fernanda, one of the older speakers in the sample (she is 53), uses creaky voice frequently, which suggests that it is not necessarily a recent development in Chicano English.
Carmen gives a passage from a narrative (by "Veronica") with the creaky-voice regions italicized. She notes that the meaning of this feature is by no means clear:
Although Laver states the 'used throughout an utterance, creaky voice signals vored resignation, in the paralinguistic conventions of English' (1980:126), in CE and probably also in California Anglo English, its meaning seems more complicated. For example, in Veronica's story, the very last thing indicated by I was like, real scared would be boredom.
Norma Mendoza-Denton ("The Semiotic Hitchhiker's Guide to Creaky Voice: Circulation and Gendered Hardcore in a Chicana/o Gang Persona", Journal of Linguistic Anthropology 21(2), December 2011) comments on some apparent further developments:
I show how creaky voice, a type of nonmodal phonation, becomes enregistered within an early narrative context, and is then catapulted by centrifugal media forces, taken as part of a constellation of features that cluster around the persona of “hardcore Chicano gangster.” [...] I also analyze a media-based data set that includes songs about cholos by a Chicano hip hop artist, web-based text and video tutorials on how to act like a cholo, and a representation of a Chicano gangster in the video game Grand Theft Auto: San Andreas.
Creaky voice [...] has no referential meaning, no continuous segmentability, and no relative presuppositional qualities vis-à-vis its context of use. Most critically, it can't even be pronounced in isolation. Indeed, when directly questioned, users had a difficult time identifying creaky voice to comment on it (“What are you talking about?” was the response I got more than once from gang girls who were users of this speech modality, with no further elaboration or response whether I described or enacted creaky voice); speakers preferred instead to comment on the phonetic, lexical and discourse elements onto which creaky voice was necessarily docked.
I don't think this is the same thing as the phrase-final irregular long-period pitch pulses that Wolk et al. are talking about, however.
But Mae West's famous "Why don't you come up some time, see me?" has definitely got some of the Wolk et al. phonation at the end of "me":