Scientists believe that they might have figured out How Cats Purr…
To cat enthusiasts, one of the most delightful sounds is the soft rumbling purr their feline companions make when they receive a gentle scratching behind the ears. However, the mechanism behind how cats purr this contented purring has remained a mystery for quite some time.
A recent study might have finally unveiled the solution. According to scientists, domestic cats have specialized \”pads\” located within their vocal cords. These pads contain an additional layer of fatty tissue, enabling the vocal cords to vibrate at lower frequencies. This discovery is reported in the journal Current Biology.
How Do Cats Purr
The production of the distinct low-pitched purring sound by cats has long baffled scientists, as typically, low-frequency sounds are generated by larger animals with lengthier vocal cords. Researchers have now uncovered the solution in what they call \’purring pads\’, which are clusters of connective tissue embedded within the cat\’s vocal folds. These pads seem to increase the density of the vocal cords, causing them to vibrate more slowly and produce the comforting rumble that brings joy to cat parents.
Leading an international team, voice scientist Christian Herbst from the University of Vienna in Austria challenges the widely held belief that active muscle contractions are responsible for purring. Instead, the researchers propose that purring might be a passive aerodynamic behavior that continues automatically after the brain initiates it.
In their published paper, the researchers note, \”These low-frequency vocal fold vibrations involve a special vocal mode with an unusually long closed quotient, reminiscent of the \’vocal fry\’ register in humans.\” When humans use vocal fry, they create a low-pitched, raspy sound by vibrating their vocal cords at a very low frequency. Various factors, including the thickness of the opening, tension in the vocal cords, and airflow, contribute to this effect.
The purring pads function similarly, enabling small cats to purr even though their vocal cords are much shorter than ours, using the same mechanisms typically employed for higher-frequency vocalizations like meowing. The connective tissues in the vocal cords, composed of collagen and elastin fibers, form structures that, much like in roaring cats, muffle the high frequencies of their sounds. While these structures, measuring up to 4 millimeters in diameter, had been previously identified in domestic cats, their role in purring had remained unexplored.
To investigate further, Herbst and his team removed the larynges, which house the vocal cords, from eight deceased domestic cats. They brought the vocal cords together and passed warm, humidified air through them. Remarkably, all eight larynges produced a purring sound without any muscle contractions or neural input, sustaining vocal fold oscillations within the range of domestic cat purring, between 25 and 30 Hz.
This surprising discovery suggests that muscle contraction is not an essential component of purring.
The connective tissue structures might be the primary drivers, although confirming this would require observing the process in living cats, which presents certain challenges.
This research could open up new avenues for understanding the role of purring in cats\’ health and well-being. It may also lead to the development of innovative technologies that mimic purring sounds, such as calming devices for cats or novel treatments for pain and anxiety.
Why Do Cats Purr
Cats engage in purring for a range of purposes, which encompass expressing emotions like happiness or fear and utilizing it as a defensive measure. Research has demonstrated that felines, employ purring as a means to alleviate pain and provide self-soothing. Purring manifests as a gentle, buzzing sound akin to a rolled \’r\’ sound, characterized by a fundamental frequency of approximately 25 Hz.
This acoustic phenomenon accompanies noticeable vibrations on the body\’s surface and follows a rhythmic pattern synchronized with the act of breathing, persisting continuously during both inhalation and exhalation. The purring\’s intensity and duration can also fluctuate based on the animal\’s level of arousal.
The enigmatic purring of our feline companions has long fascinated both scientists and cat lovers alike. While there is still much to learn about the many facets of our beloved cats, this discovery brings us one step closer to understanding these graceful creatures and the unique ways in which they communicate with us. As our knowledge of cat behavior and physiology continues to expand, it only deepens our appreciation for the remarkable bond we share with our purring friends.