Adaptive filter calculation method and sound field generating device

A sound field generating device comprising:

• an identifying unit that identifies an auxiliary filter for an inverse system including an adaptive filter that has an inverse characteristic of a reproduction sound field characteristic, which is a sound field characteristic of an environment where a sound source as an input signal is reproduced, and that is arranged in series with a stage previous to an output stage of the reproduction sound field characteristic, and the auxiliary filter that updates the adaptive filter and that is arranged in parallel with an output stage of an arbitrary sound field characteristic, the identifying unit being configured to identify the auxiliary filter based on the arbitrary sound field characteristic as a target using either the adaptive filter with an initial value-set therein or the adaptive filter having been updated;
• an updating unit that updates the adaptive filter using the auxiliary filter identified by the identifying unit;
• and
• an adaptive-filter superposing unit that, when update of the adaptive filter satisfies a predetermined end condition, superposes the adaptive filter updated by the updating unit on the reproduction sound field characteristic.