Signal processor and signal processing method

A signal processor, comprising:

• an input unit configured to receive a first audio signal and a second audio signal including mutually correlated components;
• a delay unit configured to delay the first audio signal received at the input unit by a prescribed delay time;
• a synthesis unit configured to synthesize the first audio signal having been delayed by the delay unit with the second audio signal received at the input unit, and outputs a third audio signal resulting from synthesis;
• and
• a frequency band restriction unit configured to restrict a level of the first audio signal before the synthesis performed by the synthesis unit in a prescribed frequency band including a frequency of a dip occurring at a lowest frequency among a plurality of dips otherwise occurring in a frequency characteristic of the third audio signal as a result of the synthesis performed by the synthesis unit.