A mixing apparatus includes: a first speaker set processing unit to a P-th speaker set processing unit. K-th speaker set processing unit (K being an integer from 1 to P) includes: a mic set processing unit configured to process acoustic signals output by two microphones of a corresponding microphone set and to output a first acoustic signal and a second acoustic signal. The mic set processing unit configured to process acoustic signals output by two microphones of a corresponding microphone set based on an expansion/contraction coefficient for determining an expansion/contraction rate of a sound field, a shift coefficient for determining a shift amount of a sound field, and an attenuation coefficient for determining an attenuation amount of an acoustic signal output by a microphone.