How Do Cats Purr ? Scientists Believe They Have Figured It Out

In a groundbreaking revelation that stands as a significant milestone in feline science, researchers have announced a pivotal breakthrough in unraveling the mysteries behind a cat’s purr. This momentous discovery challenges our previous understanding of the mechanisms responsible for this iconic feline sound, shedding light on the remarkable autopilot nature of a cat’s purring.

The key to this distinctive signature sound lies in the intricate interplay of squishy pads within a cat’s vocal cords. Scientists have long grappled with the enigma of how these seemingly diminutive creatures, with shorter vocal cords, manage to produce a unique low-pitched cats purr, a phenomenon typically associated with larger animals possessing elongated vocal cords.

The newfound focus centers on these enigmatic ‘purring pads’—specialized connective tissue embedded within the vocal folds. These pads, intriguingly, contribute to increasing the density of the vocal cords, inducing slower vibrations that culminate in the characteristic rumble that brings delight to cat owners worldwide.

How do cats purr – what does science say ?

The groundbreaking research conducted by an international team, spearheaded by voice scientist Christian Herbst from the University of Vienna in Austria, presents a paradigm shift by challenging the widely held belief that active muscle contractions are the primary cause of purring in cats.

Instead, these pioneering scientists propose an alternative perspective, suggesting that purring may be a passive aerodynamic behavior that unfolds automatically after the brain initiates the signal. In their published paper, the researchers delve into the intricacies of low-frequency vocal fold vibrations, unveiling a distinctive vocal mode characterized by an unusually long closed quotient.

Drawing parallels to the “vocal fry” register in humans, this mode creates a low-pitched, raspy sound through the vibration of vocal cords at an exceptionally low frequency, often likened to a ‘droning’ or ‘gravelly’ voice. The thickness of the opening, the level of tension in the vocal cords, and the airflow through them collectively contribute to this unique vocalization.

The mechanism behind these feline vocalizations involves what the researchers term as “purring pads.” These specialized connective tissue structures embedded in the vocal folds play a crucial role in enabling small cats to purr, despite having significantly shorter vocal cords compared to humans.

Remarkably, these ‘purring pads’ operate using the same mechanisms that typically generate higher-frequency vocalizations like meows. Within these connective tissues, collagen and elastin fibers are organized in structures that share similarities with those found in roaring cats, effectively dampening the high frequencies of their sounds.

Although these structures, measuring up to 4 millimeters in diameter, had been previously identified in domestic cats, their specific role in the purring process had remained unexplored until this groundbreaking research.

To delve deeper into the dynamics of purring, Herbst and his colleagues embarked on a meticulous investigation, removing the larynges housing the vocal cords from eight deceased domestic cats. Through a controlled process, they pressed the vocal cords together and facilitated the flow of warm, humidified air through them, revealing crucial insights into the intrinsic mechanisms of feline purring.

While the study provides a foundational understanding, further exploration in living cats is warranted to ascertain the full extent of these fascinating revelations.

In a remarkable revelation, the research experiment involving the removal of larynges from eight deceased domestic cats yielded unexpected results: the generation of a purring sound without any involvement of muscle contractions or neural input. The self-sustained vocal fold oscillations produced frequencies within the range of typical domestic cat purring, specifically between 25 and 30 Hz.

This discovery challenges the conventional belief that active muscle contractions are indispensable for the purring process. The focus shifts to the connective tissue structures within the vocal folds as potential key drivers of purring, although further validation through measurements in living cats is a more intricate endeavor.

While the data presented by the research team does not categorically negate the active muscle contraction hypothesis for purring, it compellingly demonstrates that cat larynges can autonomously generate sounds within the purr frequency range, ranging from 25 to 30 Hz, devoid of neural input or muscular contraction.

The enigma surrounding the purpose of cat purring persists, with various theories positing that it signifies contentment and serves to foster increased interaction with humans. Additionally, research suggests that purring might possess healing properties, further deepening the mystery.

The implications of this research extend beyond unraveling the mysteries of feline purring, potentially offering novel insights into the role of purring in the health and well-being of cats. This newfound knowledge opens avenues for the development of innovative technologies that replicate the soothing sounds of purring, such as calming devices for cats.

Moreover, it hints at the possibility of devising new treatments for conditions like pain and anxiety in feline companions, marking a promising frontier in feline healthcare advancements.

Reference: Current Biology