Ted's Cat Purr Recording helped my neck pain about 25%. This is what I found online:
Veterinarians have long noted that broken bones heal quickly in cats. The vibrations associated with the feline purring is of interest to the holistic healing community. The measurable Hertz of a cat's purr lies between 25 and 150. 20 to 50 HZ have shown great promise in speeding bone injuries in human medicine. Research is currently being done to find out if purring actually accelerates the natural healing process of broken bones in humans. "Here kitty, kitty", says the woman with a broken ankle.