To allow a sound field having a surround effect to be recognized from any direction with respect to a stereo audio device having left and right speakers provided together in one small-sized enclosure.

Two or more speakers which are provided in an internally closed speaker enclosure and have a common back space are divided into two groups, and a stereo left channel signal is supplied to speakers in one group, and a stereo right channel signal is supplied to speakers in the other group. The surround effect is given to stereo signals, and stereo right and left channel signals after giving of the surround effect are supplied to speakers in one group and speakers in the other group respectively.