Apparatus for expanding and controlling sound fields

An apparatus for correcting asymmetrical sound fields at a listener's position as in an automotive vehicle compartment in which right and left loudspeakers are disposed at positions angularly different relative to the listener's position, wherein stereo-sound signals from an acoustic signal source are output as acoustic signals of fundamental sounds to the right and left loudspeakers and, at same time, effective sounds, such as early reflection and reverberation sounds, are formed for right and left channels by arithmetically processing the acoustic signals of fundamental sounds, which acoustic signals of right- and left-channel effective sounds are outputted respectively to the right and left loudspeakers respectively. Furthermore, a signal which corrects at least one of the phase and level of the left-channel acoustic signal of fundamental sound, and a signal which corrects at least one of the phase and level of the left-channel acoustic signal of effective sound are supplied to the right channel loudspeaker or a center channel loudspeaker disposed between the right and left loudspeakers. Likewise, signals which corrects at least one of the phase and level of the right-channel acoustic signal of fundamental sound and of the right-channel acoustic signal of effective sound are supplied to the left channel loudspeaker or the center channel loudspeaker.