Signal processing device and signal processing method

A signal processing device, comprising:

• a band detecting unit configured to detect a frequency band which satisfies a predetermined condition from an audio signal;
• a reference signal generating unit configured to generate a reference signal in accordance with a detection band by the band detecting unit;
• a reference signal correcting unit configured to correct the generated reference signal on a basis of a frequency characteristic of the generated reference signal;
• a frequency band extending unit configured to extend the corrected reference signal up to a frequency band higher than the detection band;
• an interpolation signal generating unit configured to generate an interpolation signal by weighting each frequency component within the extended frequency band in accordance with a frequency characteristic of the audio signal;
• and
• a signal synthesizing unit configured to synthesize the generated interpolation signal with the audio signal.