An audio system includes an audio device and a control device. The control device receives a second broadcast signal for an alternative frequency associated with the first broadcast signal with receive sensitivity of specified first reference sensitivity or more than the predetermined first reference sensitivity and verifies and stores a second radio frequency for transmitting the same broadcast as a radio broadcast of the first radio frequency, receives a third broadcast signal for the alternative frequency, when the first broadcast signal with receive sensitivity less than the specified first reference sensitivity, but greater than or equal to specified reference sensitivity is received, and change the frequency of the audio device from the first radio frequency to a third radio frequency, and changes the frequency of the audio device based on the second radio frequency, when the first broadcast signal with receive sensitivity less than the specified second reference sensitivity is received.