First, what does vocal fry sound like? Basically they keep their vocal chords so close together that it repeatedly and irregularly cuts off the stream of air. When the airflow is interrupted so much, it sounds like a creaking door or a croaking frog.
As an example, here is a Millennial girl using vocal fry for minutes on end. She mentions that she's taking public speaking classes, and that her teacher said she has terrible vocal fry. Yet here she is in a YouTube video slipping right back into it, that's how ingrained it is. Here is more of a caricature of what it sounds like (up through 0:40 anyway; you can skip the rest).
I didn't know there was a name for this annoying way of speaking until I read the NYT article -- fry-talkers! Just last week I heard a Millennial student give a 15-minute class presentation using vocal fry almost the entire time. It's not restricted just to younger females, though, as some fat middle-aged hag near me in Starbucks today yakked on and on into her phone with that voice. You may not have even noticed how common it is, but just listen for it and you'll be shocked.
Turning to what it all means:
So what does the use of vocal fry denote?...It can also be used to communicate disinterest, something teenage girls are notoriously fond of doing.
“It’s a mode of vibration that happens when the vocal cords are relatively lax, when sublevel pressure is low,” said Dr. Liberman. “So maybe some people use it when they’re relaxed and even bored, not especially aroused or invested in what they’re saying.”
The muscles that pull the chords together are innervated by the parasympathetic nervous system, which is the "rest and digest" system, the complement to the sympathetic nervous system ("fight, flight, fright, fucking"). Young people today are clearly more vegetative and unexcitable than young people used to be, and this over-activity of their parasympathetic nervous system is probably having side effects on their speech, making them sound robotic.
It is even more useful to see vocal fry in terms of its opposite. Its defining feature is the repeated blockage of airflow through the vocal chords, so the opposite is when too much air flows through them. The scientific jargon for this is "breathy voice." (Normal speech, with neither too much nor too little airflow, is "modal voice.") So take all of those associations with a voice that is very breathy, and then think of the opposite for vocal fry.
Breathy voice signals arousal, creaky voice signals hibernation. Breathy wants to bring the listener closer, creaky wants to keep them at a distance. In fact, breathy voice shades into whispering when the vocal chords don't vibrate much. During a whisper, there is still lots of air flowing through -- just not much vocal chord vibration to provide "voicing." Both breathy and whispery voices are less intelligible, making closeness to the speaker even more important.
So it looks like the key factor driving the increased use of vocal fry is the increase in the avoidant types of social-emotional attachment styles. The avoidant types don't want to depend on others and don't want others to depend on them. They don't let themselves get excited -- if something begins to set something else off, they rush to shut it down. They're control freaks. Part of that is that when any kind of intimacy comes into view, they either have to peel out in the other direction, or if backed against the wall, stiffen their arms out in front to keep the closeness from getting any closer.
To keep others away, they adopt an irritating voice that says you're boring them. In the good old days, the creaky-croaky voice was mainly associated with snobs. Now everybody has a condescending view of everybody.
The attachment styles called "secure" and "anxious-preoccupied" (the clingy or needy ones) are more likely to use a breathy or whispery voice. They want to establish connections, and a whisper says "come here, I have something special to tell you." We immediately relate breathy voice to seduction, for example Michael Hutchence's delivery in "Need You Tonight". However, another second's thought shows that's only one instance of the broader pattern of striving for intimacy. Barry White isn't trying to seduce someone he's just met, but trying to set the mood of closeness and not holding anything back around someone he's been with for awhile.
And Suzanne Vega isn't conjuring up anything romantic or sexual in "Luka", in which a boy whose parents beat him up talks to a neighbor about what's going on. Here the breathy voice is a signal that he's trusting the listener, opening up, and hoping that they can empathize enough so that they might help him out. Imagine how easily you could wipe out that emotional coloring by having it sung with vocal fry a la Britney Spears or Kesha.
Female voices are breathier than male voices, on average, although the difference isn't huge like it is for pitch. The dimorphism emerges around puberty, though again we shouldn't be blinkered by thoughts about courtship and mating. Puberty is also when you start becoming more independent of your parents and more reliant on a crowd of peers to belong to as your social support.
Adolescent males can protect themselves better than females can, so girls probably develop breathier voices because they're more dependent on others for security, and need to reach out and maintain intimacy more. That includes their female friends, but also the males who they'll have to recruit into their circle. Like I said the difference isn't huge, and males will have to do this stuff a lot too.
So although creaky voice could be viewed as a move toward androgyny, it's more simply explained by girls retreat from relying on others, and thus not having to use breathier voices to reach out and cement intimate relationships.
Lab experiments that manipulate female voices show that breathier voices are consistently found to be the most attractive by males. So here's a case where young women, who being at their peak for reproductive potential will supposedly go crazy to make themselves more appealing, are in fact making themselves more repulsive. And as that Millennial's YouTube clip shows, not trying to correct it even when it is pointed out and harped on endlessly.
It's hard to make sense of that unless we remember that social avoidance is the rule, so they don't care if others find them off-putting. Hence all of the pop songs with "I love haters" messages. Girls also stopped wearing make-up, stopped volumizing their hair, and stopped showing skin, so the gross-sounding voice is not an isolated case. They just don't want boys to notice them anymore... and the strategy is working.
I wrote several paragraphs about how this all applies to gay homosexuals, but that reads like a post of its own, so I'll save that for a little later.