Spending your days immersed in sound and frequency has a funny side effect: you start hearing patterns in everyday life. This particular moment started on an especially cold night in January with my cat hopping on the couch, flopping onto her back, and staring at me with amber eyes that made it very clear belly rubs were required. 

In Ronja’s household hierarchy, I am the support staff. The food lady. The chump who keeps her litter box acceptable for use. The woman who dares approach with a brush. My husband is the favorite, the chosen one, the recipient of unearned devotion. So did this feel like a momentous occasion for me? Let’s just say I recorded it for future use.

This is about the point where I imagine most people will reasonably ask, okay, that’s nice, but what does this have to do with frequency therapy? I’ll admit this has been a bit self-indulgent so far. So were the DMs I sent to a handful of people containing nothing but the recording and the words “You’re welcome.” 

Here are some of the responses I got: 

“Aww she has a very deep rolling purr 😻”

“Currently listening in surround sound 😭😭😭”

“I could just listen to this forever.”

“It just feels so *good*!”

And because sound and frequency are quite literally what we work with every day, our engineer wanted to know what was actually going on in that purr. 

Unlike meowing, purring doesn’t come from pushing air past the vocal cords in a single direction. Instead, it’s produced by rapid, rhythmic contractions of the muscles in the larynx. These contractions happen on both the inhale and the exhale, which is why a purr sounds continuous and unbroken in a way most vocalizations aren’t.

In simpler terms: the cat’s voice box is vibrating. 

It’s worth noting that cats don’t only purr when they’re happy. In fact, they also purr when they’re stressed, injured, or even just asking for something. 

A Brief (but Actually Interesting) Scientific Detour

Low-frequency vibration has been studied in human medicine for decades, particularly in relation to bones, muscles, and connective tissue. In controlled settings, researchers have found that vibration — often in the 20–50 Hz range — can support bone density maintenance, especially in populations at risk for bone loss.

For example, a well-known randomized controlled trial published in Proceedings of the National Academy of Sciences found that low-level whole-body vibration helped slow bone loss in postmenopausal women

→ Marín-Cascales et al., Whole-body vibration training and bone health in postmenopausal women: A systematic review and meta-analysis

Where Do Cats Come Into This?

Scientists have consistently found that both wild and domestic cats purr in a low-frequency range, commonly between 25 and 150 Hz— the same frequencies as in the study I just mentioned.

→ Elizabeth von Muggenthaler The felid purr: A healing mechanism?

To be clear, we aren’t suggesting that cats purr consciously to heal (though the possibility does warm my heart). What we are saying is there is evidence that: 

• Cats purr during rest, injury, stress, and recovery.
• They are prone to high-impact injuries (jumping, falling), yet have unusually fast bone healing relative to size.
• The frequencies cats naturally produce overlap with known tissue-supportive vibration ranges.

So a reasonable conclusion is that cat purring likely evolved as a low-effort way for a cat’s body to handle background maintenance. Which feels very on brand for cats. 

So Can Cat Purrs Heal Humans?

*Sigh* Unfortunately, it isn’t likely that cats have healing powers. (Don’t tell Ronja, though—who always gravitates towards sick family members.) Here is what we do know. Listening to purring sounds can: 

• Lower heart rate
• Increase parasympathetic (calming) nervous activity
• Reduce perceived stress

But in the science world, that is what’s referred to as auditory-nervous-system entrainment so it is more aligned with self-regulation than healing. 

That being said, according to the Rutherford Veterinary Hospital there’s also some evidence that the physical vibration of a cat’s purr has been associated with nitric oxide release—something the body uses to help with circulation and pain regulation.

Does the Z-App Have Any Frequencies in This Range? 

Absolutely! If you go into the main menu of the Z-App and tap “frequencies,” you will find access to frequencies ranging from 0.45 to 22037.5 Hz. You can experiment with individual frequencies or build your own custom sequences based on what you’re curious about.

I did a brief perusal of our Sequences List and looked up a few of the frequencies within the purring range (between 25 and 150 Hz as mentioned earlier.) and found that sequences such as the *Arthritis, Kidney Inflammation, and Calming sequences all include frequencies within that range! 

Granted, there are nearly 1,500 sequences so there is so much to explore. Personally, I tried playing these frequencies with just my phone speakers and didn’t particularly enjoy the sound, especially compared to listening to Ronja purr in real life. However, when paired with my Z-Amplifier, those frequencies were delivered silently through electrodes, so it was experienced as a more pleasant buzzing through my body. But that’s just my preference. 

Separately, it’s worth noting that even a cat purring at full intensity on your chest isn’t going to vibrate the human body the way it does the cat itself. That’s exactly why we designed the Zappkit. A cat’s purr is a lovely example of how frequencies show up in nature, but it works internally for them. Our Z-Amplifier gives humans a way to experience those same frequency ranges—and far beyond—delivered directly to the body in a more powerful way. No fur required. 

We Aren’t Suggesting You Replace Your Cat With a Device. (Please don’t.) 

This was never really about turning a cat into a case study. It was about curiosity. About noticing patterns. About letting something small and comforting lead to a deeper look. Which, honestly, feels like a pretty good way to approach most things.

*Disclaimer: This post is shared for educational and curiosity-driven purposes only. It is not intended to diagnose, treat, cure, or prevent any medical condition. Individual experiences with sound, vibration, or frequency may vary, and any medical concerns should be discussed with a qualified healthcare professional.