A bypass passage connecting an upstream portion and a downstream portion of a compressor of a turbocharger is provided in an air intake passage of an internal combustion engine. The paper engaging mechanism comprises an engaging arm and an engaging roller. Thus, an audio communication function can be added to a packet communication device, thereby realizing a VoIP function to a wireless circuit using an audio communications circuit. As a result, according to the present invention, the reliability of the semiconductor device can be improved while a cost is reduced. The Z-shaped channel members and compressed straw panel each being capable of partially attenuating sound energy passed therethrough. The voltage command generator decreases the voltage command value if the output current increases, to prevent the rotation speed of a prime move from suddenly changing.