Project Description: The Purr Pad is a pad that improves bone density and promotes healing. Cats purr with a frequency between 25 and 150 Hertz. The Scientific American says that many scientists have discovered that this sound frequency can “improve bone density and promote healing.” Our invention is a pad that you can get for your bed or a small version that you can use to help your body heal. Hospitals can put them on the bed to help people relax and heal. You can also buy them to use at home to help you relax and heal. Small versions can be used to help if you have a broken bone.