You’ve heard it before. That low-pitched, raspy, croaking sound, normally found toward the end of a sentence and extended for longer than what seems normal. Commonly known as vocal fry, the sound also goes by “creaky voice,” “croak” or the less conversation-friendly “glottalization” and “laryngealisation.” It occurs when cartilages in the larynx draw together, causing the vocal cords to compress tightly and become compact, forming a large and irregularly vibrating mass within the larynx in the process. Air travelling through the larynx rattles and pops, emitting a low-frequency sound reminiscent of a slowly creaking door.

Anecdotal evidence has shown that many people find vocal fry, especially when produced by women, difficult to bear. More formal studies have traced the tangible effect that vocal fry’s unpopularity has on women. A study led by researchers at Duke University has shown that prospective employers view job candidates (and women in particular) who use vocal fry as being “less competent, less educated, less trustworthy, less attractive, and less hirable,” which the study claims hurts those women’s performance on the job market. Studies like these have given many people cause for concern, especially since other studies show that vocal fry is quickly becoming a part of the linguistic mainstream in the United States, and among young women in particular.

To uncover why someone might find something as seemingly innocuous as low-frequency vocal pitch irritating, we spoke with John Ohala, phonetician and Professor Emeritus at UC Berkeley and a pioneer in the field of phonology. Ohala has studied the relationship between low-frequency vocal pitch and speech perception in humans from the perspective of ethology, or the study of human and non-human behavior. He emphasizes that, in order to understand pitch perception among women and men, we first need to think about what pitch and analogous vocal and visual cues accomplish in the animal world.

Take, for example, the image of an adult male lion, a beautiful mane wrapped around his head. As is well known, males of certain species—not just lions, but also peacocks and mallards and many others—develop elaborate aesthetic qualities like manes and intricately patterned feathers to attract the attention of (and compete for) female mates. These features are designed to give males a leg up in reproducing (and passing along their genes) through a force known as sexual selection.

Conflict minimization between members of the same (and different) species plays a similarly important role in ensuring a species’ survival. Although competition and the conflict that comes with are central to Darwin’s theory of evolution, too much of both can be harmful. Luckily, most animal species have developed innate mechanisms—both physical and behavioral—that help them distinguish unproductive conflicts from those that may result in a useful immediate or long-term outcome. Some of the most important mechanisms for doing so rely on projecting size and strength.

In the case of lions, not only does the mane demonstrate a male's superior fitness for the purpose of mate selection, but it also artificially increases his size to signal to those around him that it would not be in their best interest to engage in combat with him. A lion’s large mane may deter a younger or smaller male lion from engaging in a sparring match with his larger counterpart, a fight that would likely result in the smaller male lion’s defeat (which would subsequently cause harm to the male lion’s family and pack). Gorilla “beards”, bison humps, and moose antlers accomplish a similar goal of minimizing conflict: by making animals appear larger, more mature, and therefore powerful, they encourage other animals to submit in what ethologists call “agonistic encounters,” or combative situations. Counterintuitive as it might be, large size—at least in the animal kingdom—could serve a pacifying purpose.

Sound, and vocal pitch in particular, plays an equally important role in settling conflicts in the animal kingdom by manipulating perceptions of size. In a seminal article published in 1977, the ethologist Eugene S. Morton argued that birds and mammals use sound to convey dominance and submission during agonistic encounters: in a potentially hostile situation, dominant animals resort to harsh, relatively low frequency (i.e., low-pitch) sounds, while less-dominant animals use higher-frequency (i.e. high-pitch) sounds designed to signify appeasement and friendliness. He argued that these behavioral tendencies are the result of natural selection and help the survival of species. Theoretically, an animal that hears a low-pitched voice, song, or noise would interpret that sound as coming from a large animal, and submit accordingly.

Take the familiar example of two dogs on the verge of fighting over a bowl of food. If one dog emits a low-pitched growl, the other normally responds with a high-pitched whimper, conceding defeat by backing away from the coveted food. The growling dog’s low-pitched voice alerts the whimpering dog to the fact that, because he is in the presence of what sounds like a larger animal, it would be in the best interest of both parties involved if he (the smaller dog) submits to his dominant opponent, rather than engage in a conflict that he would likely lose.

Ohala was intrigued by Morton’s study of the relationship between vocal pitch, size projection, and conflict resolution, and tried to uncover whether the same dynamic could be observed in humans. In 1984, he published an article in which he outlined what he described as the "frequency code," an innately programmed system in humans that associates low frequency, low-pitch voices with larger size and dominance, and high frequency, high-pitch voices with smaller size and less dominance. In other words, like the dogs fighting over a food bowl, humans are evolutionarily prone to associate a lower pitch with aggressiveness and a higher pitch with weakness.

To see how the Frequency Code manifests itself in humans, consider two examples: the “Adam’s Apple,” and the smile.

As noted, vocal fry occurs when air travels through the larynx at the same time as vocal cords compress, producing a low-pitch, low-frequency sound; the larger the mass of the vocal cords, the lower the pitch. After puberty, boys develop anatomical traits that promote low-pitch vocal production, primarily through larynx and vocal cord growth. In young men, the larynx grows so much that it often forms a large protrusion on the front of the neck, the so-called “Adam’s Apple,” and vocal cords grow by as much as 50% in length and 100% in mass. Large larynxes and heavy vocal cords encourage low-pitch production, and when that low-pitched sound gets emitted, they signal to those around them—whether fellow mature males, less mature males, or women—that they are in the presence of a dominant, mature adult.

While larynx and vocal cord growth enable individuals to project dominance through low-pitch production, the smile, according to Ohala, does the opposite.

While larynx and vocal cord growth enable individuals to project dominance through low-pitch production, the smile, according to Ohala, does the opposite. While some researchers have interpreted the display of one’s teeth by way of the smile as an act of aggression, Ohala argues that smiles signal an individual’s smaller size by increasing the resonance of the sound emitted from the vocal cords. Resonance depends on several factors, but the length of the vocal tract is especially influential: generally speaking, short vocal tracts (typical of smaller animals) produce high-resonant sounds, while local vocal tracts produce low-resonant sounds (typical of larger animals).

Smiles allow animals to overcome the biological features that nature had bestowed upon them by artificially and temporarily shortening the length of the vocal tract, thereby producing a high-resonance sound to convey smaller size and goodwill. For example, a large male primate may choose to smile to appear less threatening during a quarrel with another primate. On the other hand, protruding the lips and constricting the mouth—the opposite of smiling—lowers vocal resonance and gives the impression of larger size and even aggression.

So what does the frequency code tell us about the documented disdain for the uptick in vocal fry use among American women? Ohala has not ventured into this territory, but some independent observations can be suggested. If a low-pitched voice is a sign of larger size and dominance, perhaps the increased use of vocal fry among women represents an attempt to lay claim to the power that has until recently been associated with mature males. Similarly, if smiles are designed to increase vocal resonance to demonstrate smaller size and good will, perhaps the emergence of campaigns to “stop telling women to smile” represents a parallel effort to assert strength. After all, in the animal kingdom, size—and the physical and communication mechanisms designed to express it—matter.

Image Credit: Lion, by Peter Harrison. Creative Commons 2.0, via Flickr.


  • Linguistics

Article Type

  • Research Highlights