An airfoil includes an airfoil body that defines a longitudinal axis. The airfoil body includes a leading edge and a trailing edge and a first sidewall and a second sidewall that is spaced apart from the first sidewall. The first sidewall and the second sidewall join the leading edge and the trailing edge and at least partially define at least one longitudinally elongated cavity in the airfoil body. A plurality of loose particles is enclosed in the at least one longitudinally elongated cavity.