An elastic body of an audio accessory is provided. The elastic body includes a cylindrical inner cover, at least one outer cover which is elongated from a top end edge of the cylindrical inner cover to enclose the cylindrical inner cover, the at least one outer cover having at least one inlet which partially exposes at least a part of the cylindrical inner cover, and at least one sensor module disposed on at least one of the cylindrical inner cover and the at least one outer cover and configured to generate a sensor signal related to deformation of the at least one outer cover.