There has been no sufficient study to address an issue caused in the use of an open-air type audio device. The coupling set includes a rigid ring, an opening and a clamping ring. In addition, the semiconductor device 100 also includes a protruding portion 146, being provided at least in the vicinity of a back surface of a device-forming surface of the semiconductor substrate 101 so as to contact with the through electrode 129, and protruding in a direction along the surface of the semiconductor substrate 101 toward an interior of the through electrode 129. The signal conductors at second ends of the second and third transmission lines may be connected to the signal-return conductors at second ends of the fourth and fifth transmission lines, respectively.