Engineers are developing an acoustic knee band equipped with microphones and vibration sensors that can listen and measure sounds inside the joint — and could lead to a way to help orthopedic specialists assess damage after an injury and track recovery progress.Hmm. Apparently the listening device on the knee band was created by combining microphones with piezoelectric film, which is very sensitive to vibrations. The microphones are placed against the skin.
Of course all knees make noise: pops, creaks, crackling. Often these are benign. But when you have knee pain, they're called "crepitus" and take on a new significance. It turns out, even if the noises are hard to make sense of, there is at least one message in there:
An injured knee makes markedly different sounds than a normal knee. “It’s more erratic,” according to Omer Inan, an assistant professor of electrical and computer engineering at Georgia Tech. “A healthy knee produces a more consistent pattern of noises.”
Inan, in recording the sounds knees make, has encountered challenges. Fluid that surrounds the joint interferes with sound waves, and moving your knees causes its own kind of noise that can drown out other noises that are more important.
As someone who listened hard to his injured knees, I’m interested in what they find. I do think knee sounds are meaningful, but I also think it’s very hard to figure out that meaning.