the invention aims to reduce the amount of circuitry in a receiver for receiving broadcast radio waves transmitted using an iboc system that allows simultaneous transmissions of an analog broadcast and a digital broadcast with the same content . the amount of circuitry is reduced by making provisions to reproduce only a monaural signal from an analog demodulator . to reduce the unnaturalness that may occur when switching from the digital broadcast to the analog broadcast , a blend processing section mixes the two signals in a smoothly varying ratio during the switching .