Plenary Keynote · ISIP Geneva · 2026

The Hoot-Purr Overlap Zone

Acoustic Convergence Across Biological Kingdoms

Dr. Beatrix Bumble  ·  Laboratory for Avian & Feline Dynamics, IMS
Motivation

Two very different animals. Very similar physics.

Strigiformes

Owls produce sustained low-frequency vocalisations in the 50–500 Hz range. The mechanism is well-characterised. What it does biomechanically — beyond communication — remains contested.

Felidae

Domestic cats purr continuously at 25–150 Hz using glottal dilation cycles. The vibration propagates through the musculoskeletal system. Effects on bone density and tissue stress have been proposed but not unified.

The Hoot-Purr Overlap Zone

A shared resonance band: 50–150 Hz

HPOZ
25 Hz 100 Hz 200 Hz 350 Hz 500 Hz
Purr range25–150 Hz
HPOZ50–150 Hz
Hoot range50–500 Hz
Principal Findings

Three results from the unified framework

01

HPOZ frequencies induce measurable stress-relief signatures in both avian and feline musculoskeletal tissue — identical biomechanical outcome, independent evolutionary origin.

02

Fluff-density tomography reveals a secondary resonance amplification layer in both owl facial disc plumage and cat chest fur, suggesting convergent soft-tissue tuning for the 80–120 Hz sub-band.

03

In 7 of 9 co-habiting owl–cat pairs, HPOZ vocalisation events were temporally correlated (p < 0.001). We do not yet have an explanation for this. We have a preprint.

Study Parameters

Acoustic spectroscopy & FDT, 2022–2025

847
vocalisation events recorded
9
co-habiting owl–cat pairs
0.3 mm
FDT scan resolution
p < .001
co-vocalisation correlation

Field recordings collected across 14 months of nocturnal observation. Ethics board approval obtained on the third submission.

Conclusion
"The HPOZ is not a curiosity. It is a cross-kingdom convergence on a biomechanical optimum. Two lineages, separated by 300 million years of evolution, arrived independently at the same frequency band for stress relief. That is not a coincidence. That is physics." — B. Bumble, closing remarks
Thank you

Bumble (2026) · J. Interspecies Physics · DOI 10.1234/jip.2026.001

Questions, preprint requests, and owl-cat co-habitation data welcome.