A diffuser which forms a first acoustic passage that sound waves propagate and which radiates the sound waves to an outer diameter direction between a diaphragm and an annular conical surface of a first reflection member, and forms a second acoustic passage the sound waves which pass the opening of the first reflection member propagate and which radiates the sound waves to an outer diameter direction between the annular concave surface of the first reflection member and a conical surface of a second reflection member.