Shamanic practice typically employs a sound-maker such as a drum or a rattle to create a rhythm that guides the practitioner into a trance or altered state of consciousness. I have a drum that I treasure, but being in a situation where drumming is too noisy, I prefer using the rattle. I make my own with rawhide, deer antlers, and crystals.
The noise of the rattle is gentle, like rain or the rustling of trees, but surprisingly powerful. A steady beat transports me into trance and the Otherworld. It is said that the human brain responds to certain wavelengths of sound in very specific ways, and you can practice with the rattle to find the beat that best puts you into an altered state of consciousness.
Like any sacred object, the rattle can be made to carry symbolism that ties the practitioner to spirit. The rattle becomes a friend with a spirit of its own, and is cared for with reverence.