Demodulation apparatus, reception apparatus, and demodulation method

A reception apparatus comprising:

• an antenna configured to capture an analog radio broadcast wave and a digital radio broadcast wave being simultaneously broadcasted, the digital radio broadcast wave including an audio signal indicative of a same content as an audio signal included in the analog radio broadcast wave, and;
• a receiver configured to receive an first signal and a second signal, the first signal being modulated into the analog radio broadcast wave and the second signal being modulated into the digital radio broadcast wave captured by the antenna;
• an analog audio demodulator configured to demodulate the first signal into an analog audio signal and output the analog audio signal;
• a digital audio demodulator configured to demodulate the second signal into a digital audio signal and output the digital audio signal;
• a selection circuit configured to select, as an output audio signal, either the analog audio signal or the digital audio signal;
• and
• a noise addition circuit configured to add noise to the digital audio signal in a first period including a switching period for switching from a state where the analog audio signal is selected as the output audio signal to a state where the digital audio signal is selected as the output audio signal.

A demodulation method implemented by a computer, the method comprising:

• demodulating a received signal of an analog radio broadcast wave and outputting an analog audio signal;
• demodulating a received signal of a digital radio broadcast wave and outputting a digital audio signal, the digital radio broadcast wave including an audio signal indicative of a same content as an audio signal included in the analog radio broadcast wave and being broadcasted simultaneously with the analog radio broadcast wave;
• selecting, as an output audio signal, either the analog audio signal or the digital audio signal;
• and
• adding noise to the digital audio signal in a first period including a switching period for switching from a state where the analog audio signal is selected as the output audio signal to a state where the digital audio signal is selected as the output audio signal.