A combination noise blocking headset and alarm clock, having a pair of padded earpieces for blocking out ambient noise so that a commuter can sleep or read on a subway or train without distractions, and having an alarm clock unit within one of the earpieces for waking up or alerting the user at a predetermined time. Since the potential of the N epi layer can be made equal to that of the P diffusion layer, it is possible to prevent the electron supply from the P diffusion layer to the invalid area even when electrons are supplied to the device formation region by a counterelectromotive force produced by a load having an inductance L. The molded rear insert member includes a cap member and with positioning of the cap member providing for the headphone being in a first mode of operation where the channel extending through the interior of the headphone is open and a second mode of operation where the channel extending through the interior of the headphone is closed.