Cats purr by dilating and constricting the glottis, which is the part of the larynx that surrounds the vocal cords. When a feline is either at her most contented, or in need of soothing and self-repair, the vibration of air as she breathes in and out makes this characteristic sound.
However, these noises have a physically rejuvenating effect on hoomans as well. The wavelength of a puss’s purr is between 25 Hertz and 150 Hertz; this corresponds with established healing electrical and vibrational frequencies in therapeutic medicine.
At the lower end of the scale, sound oscillations between 25Hz and 50Hz improve bone density and growth, whereas higher amplitudes are beneficial for those with muscle atrophy as they assist in healing skin and soft tissue. Hoomans report dyspnoea and migraines easing in the presence of their purring furry friend, and since endorphins are released with a subsequent reduction in stress hormones, this often results in lower blood pressure. Owning a cat can cut the risk of heart disease or stroke by a third, so never underestimate the healing power of the purr. ❤
~ Tania Marie de Saram