A surround system includes a decoder that decodes an encoded audio data stream, a decorrelation unit that receives and decorrelates stereo signals decoded by the decoder so as to generate surround signals having a low-correlation component, an addition unit that adds high-correlation-component signals extracted from the stereo signals to the surround signals generated by the decorrelation unit, and a controller that controls addition of the high-correlation-component signals performed by the addition unit on the basis of the bit rate of the audio data stream.