The rat's 22 kHz call: the inaudible distress signal worth learning to spot
Rats don't only communicate through cheerful play calls: they also have a distinct alarm signal, produced around 22 kHz, mostly inaudible to the human ear. Find our daily care guidance in the rodent care and grooming section.
An alarm signal studied in detail
Brudzynski published a review of the pharmacological and behavioral characteristics of 22 kHz alarm calls in rats in the journal Neuroscience & Biobehavioral Reviews in 2001 (research on Google Scholar). These low, sustained calls, produced by a cholinergic neural circuit distinct from the one behind 50 kHz play calls, typically appear in response to a perceived threat: a predator approaching, rough handling, pain, or anticipation of something unpleasant. Unlike play and contentment calls, they're almost always paired with wary stillness rather than curious approach.
Why this signal is so hard to catch
Its frequency, well above the human hearing threshold, makes this call completely invisible without an ultrasonic detector — unlike 50 kHz play chirps, some harmonics of which can occasionally be heard. An owner can therefore miss a genuine sign of distress in their rat without ever hearing it.
- Watch for the associated visual cues: frozen stillness, pinned-back ears, an attempt to flee or retreat to a dark corner of the cage.
- Avoid rough handling or sudden movements near the cage, common triggers for this distress signal.
- Adjust handling after a visible stress episode: a slower approach, a calm voice, a pause before trying again.
This stress response fits into a broader physiological mechanism, covered in our article on rodent handling and the stress response. On the flip side, the positive calls linked to play are explained in our guide on rat laughter during tickling.
Frequently asked questions
Can the 22 kHz call be heard without special equipment?
No, this frequency is above the human hearing limit; only an ultrasonic detector picks it up directly.
Does a rat making this call always mean real danger?
Not necessarily: unfamiliar handling or a sudden noise are enough to trigger it in an animal that's simply startled, with no real threat present.
Does this signal only affect poorly socialized rats?
No, it's an innate behavior present in all rats, even those very used to handling; only how often it shows up varies by individual history. Find all our guides on the rodent hub.
This guide is part of Planète Pets’s Rodents universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.