The following papers have been referenced a lot in media stories about fry. However, as I show, none of them conclusively prove that fry is new, bad, good, or pathological. The gender difference in fry could be a result of sexual dimorphism (see discussion on Language Log). Given the probably vast speech corpora available, surely it wouldn’t be difficult to improve the state of the literature?
Perceptions of Fry 
This study, reported in a linguistics journal, compared perceptual/acoustic findings from 11 male and 12 female speakers of Californian English (students at UC Berkeley). It found American females using creaky voice twice as often as Japanese females or American males.
For the second part of the study, one voice recording from the first part was selected and presented to 175 college students at UC Berkeley and the University of Iowa, who were asked “what kind of impressions” they had of the woman who produced the voice. About four-fifths of listeners reported recognising the feature (interestingly, 90% in Iowa and 60% in California – the disparity is not discussed). The overwhelming impressions were “professional“, “upwardly mobile” and “urban“. No evidence is presented that vocal fry was the phenomenon the listeners associated with these impressions.
Conclusions: Female college students fry more than male college students. One speaker who uses vocal fry is thought of as sophisticatedly urban. It’s a stretch to say that fry is intrinsically urban or professional.
Prevalence in Young Adult Males & Females [2,3]
In this study, the authors worked from the position that fry is both a pathological sign and present in normal speakers – which renders its clinical utility as part of a perceptual profile a bit suspect, no? The goal of the study was to “quantify the prevalence of vocal fry in a population of young, female, SAE [Standard American English], college students” (p.e112 – my emphasis). The protocol involved sentence reading and vowel production.
That’s five modifiers, but we should add two more: firstly, that the students were all at Long Island University; and secondly, that they consented to appear in this study (volunteer bias). This doesn’t affect the validity of a narrow reading of the results, but often a broad reading is reported. Wolk (the lead author) was quoted as saying “Although it’s not exclusively used by young women, they seem to use verbal fry more frequently than young men or older individuals.” – which I suppose is more sexy than saying “Although it’s not exclusively used by young, female, SAE-speaking, Long Island-residing, college students who consented to be in the study…etc.”
The team found a prevalence of about two-thirds (n=34). In the Discussion they note that “knowledge of the extent of vocal fry usage in college students may have very important long-term consequences for vocal health”, citing Colton’s textbook Understanding Voice Disorders as a reference. While Colton is a fine author and clinician, no evidence is provided in this text for this assertion.
In a follow-up study, the team repeated the protocol with male, SAE-speaking, Long Island University-attending, 18-25 yr old students (n=34), but did not recruit further female students, instead choosing to use the old data. No proportion was reported (“vocal fry was rarely used”).
Conclusions: This doesn’t tell us a lot, other than confirming that female college students fry more than male college students. The judges seemed to have difficulty agreeing on fry (which is a fairly noteworthy feature as my previous post shows). Describing Kappas of 0.48 and 0.49 as “high agreement” seems stretched (The standard reference calls for at least .7 for a “reliable” instrument 
You won’t get a job with Fry 
The PLoS One article which received quite a bit of attention (see Part One of this series). It didn’t begin well, quoting many anecdotal sources as one might quote evidence in an Introduction. 14 speakers (7 male, 7 female) produced the phrase “thank you for considering me for this opportunity” in their “normal tone” and in vocal fry (“mimicking”). These recordings were then presented in random pairs to 800 internet-based listeners who answered questions like “who is more competent?”. The researchers found that the listeners, both male and female, preferred the “normal tones” to fry at a rate greater than chance. The researchers conclude that vocal-fry is perceived negatively, and may result in “negative labor market perceptions”. They also note its prevalence is increasing.
- The fry samples were not real fry but imitation
- The samples did not differ in just fry but also in
- duration of the sentence
- duration of individual words
- perceived vocal effort
- The “normal tone” examples had some fry as well!!! (you can listen to all the stimuli on the PLOS website)
To these I’ll add:
- Nobody would base the decision to hire solely on your voice (except perhaps this person).
- The judges did not work in recruitment.
Conclusions: This paper’s methodological flaws seem fatal to its conclusion. Perhaps we could say people imitating a vocal style they do not use do not sound trustworthy or convincing?
- Yuasa, I. P. (2010). Creaky Voice: A new feminine voice quality for young urban-oriented upwardly mobile American women? American Speech, 85(3), 315-337.
- Wolk, L., Abdelli-Beruh, N. B., & Slavin, D. (2012). Habitual use of vocal fry in young adult female speakers. Journal of Voice, 26(3), e111-e116.
- Abdelli-Beruh, N. B., Wolk, L. & Slavin, D. (2014) Prevalence of vocal fry in young adult male American speakers. Journal of Voice, 28(2), 185-190.
- Landis, J. R., Koch, G. G. (1977). The measurement of observer agreement for categorical data. Biometrics 33:159-174
- Anderson, R. C., Klofstad, C. A., Mayew, W. J., & Venkatachalam, M. (2014). Vocal fry may undermine the success of young women in the labor market. PLoS ONE, 9(5)