In order to measure the domestic cat’s purrs and how purr vibration is spread throughout its body ENDEVCO Model 22 accelerometers were used. Weighing a mere 0.14 gram, this is the world’s smallest accelerometer. It mounts adhesively, requires no external power and is ground isolated. It is typically used on such small objects as scaled models, circuit boards and disk drives.
During tests, the cats relaxed on blankets, and were encouraged to purr by occasionally stroking them. The small, lightweight Model 22 accelerometers were placed directly on the skin of the cats and stabilised using washable make-up glue and medical tape. Each recording session lasted between 6 and 10 minutes. Data was recorded on DAT recorders and analysed.
Results indicated that despite size and different genetics, all of the individual cats have strong purr frequencies that fall within the range of a multitude of therapeutic frequencies and particular decibel levels, see Fig. 3.
So says the study “Solving The Cat’s Purr Mystery using Accelerometers,” Elizabeth von Muggenthaler and Bill Wright, Bruel and Kjaer Magazine, no. 1. 2003.
(Thanks to investigator Janice Ewing for bringing this to our attention.)