Abstract: A speaker unit has at least a part that is installed in a first space separated by a wall from a second space in which a sound to be output by the speaker unit is listened to. The speaker unit includes a first speaker, a second speaker, a speaker connector that interconnects the first speaker and the second speaker so that back surfaces of the first speaker and the second speaker oppose each other, a first spacer that interconnects the first speaker and a first opening of the wall, and a second spacer that interconnects the second speaker and a second opening of the wall. The first speaker, the second speaker, the speaker connector, the first spacer and the second spacer are integrally connected to each other.

Abstract: For an inverse system including an adaptive filter having an inverse characteristic of a reproduction sound field characteristic and arranged in series with a stage previous to an output stage of the reproduction sound field characteristic, and an auxiliary filter for updating the adaptive filter arranged in parallel with an output stage of an arbitrary sound field characteristic, the auxiliary filter is identified based on the arbitrary sound field characteristic as a target using the adaptive filter with an initial value set therein or the adaptive filter having been updated. The adaptive filter is updated using the auxiliary filter thus identified. When update of the adaptive filter satisfied a predetermined end condition, the adaptive filter thus updated is superposed on the reproduction sound field characteristic.