Filter generation device and filter generation method

A filter generation device, comprising:

• a processor coupled to a memory storing instructions to make the processor to function as:
• a frequency characteristics acquisition unit configured to acquire frequency characteristics based on sound pickup signals;
• a level calculation unit configured to calculate a reference level in the frequency characteristics;
• a correction unit configured to correct the frequency characteristics so that the frequency characteristics fall within a predetermined level range including the reference level, and thereby calculate corrected characteristics;
• and
• a filter generation unit configured to generate a corrected filter based on the corrected characteristics,
• wherein the frequency characteristics acquisition unit:
• acquires first frequency characteristics based on first sound pickup signals picked up by a left microphone worn on a left ear of a user;
• and
• acquires second frequency characteristics based on second sound pickup signals picked up by a right microphone worn on a right ear of the user,
• wherein the level calculation unit calculates a common level for the first frequency characteristics and the second frequency characteristics,
• wherein the correction unit calculates first corrected characteristics obtained by correcting the first frequency characteristics, and second corrected characteristics obtained by correcting the second frequency characteristic, and wherein the filter generation unit:
• performs inverse Fourier transform on each of the first corrected characteristics and the second corrected characteristics, and thereby generates first corrected signals and second corrected signals in a time domain;
• and
• adjusts levels of the first corrected signals and the second corrected signals to maintain a power ratio between left and right, before and after the correction.