Research overview: acoustic structure and proposed frequencies of the cat purr

The purr has a characteristic low fundamental frequency, and this overview reviews its acoustic structure and the claims made about specific frequencies. Measured purrs typically centre on low frequencies in the tens of hertz, with harmonics, and the rhythmic muscle activity that drives them sets the rate. Popular claims that particular frequencies promote healing are widely repeated but rest on limited evidence and are flagged here as speculative. Researchers characterise the purr through spectral analysis across individuals and contexts. Why it matters: an accurate acoustic description of purring grounds discussions of its function and mechanism, separates measured fact from frequently repeated but unverified health claims, and provides the quantitative basis for comparing purrs among cats and for testing hypotheses about why this unusual, sustained vocalisation evolved.