Audio signal processing method and apparatus for frequency spectrum correction

An audio signal processing apparatus comprising:

• an input terminal provided to receive an input audio signal;
• a processor configured to:
• obtain a difference between a playback loudness of the input audio signal and a desired loudness thereof,
• correct a frequency band spectrum of an output audio signal for each of a plurality of frequency bands based on the difference between the playback loudness and the desired loudness of the input audio signal and a relationship between a loudness and a sound pressure for each of the plurality of frequency bands, and
• apply a loudness modification gain to the output audio signal of which frequency band spectrum is corrected, wherein the loudness modification gain is obtained based on the desired loudness and a loudness of the output audio signal of which frequency band spectrum is corrected;
• and
• an output terminal provided to output the output audio signal,
• wherein the playback loudness is a loudness of the output audio signal when the input audio signal is output without the correction,
• wherein the loudness modification gain is obtained below equation,
• DL_Int_Predict=(L_EQ_Ref−L_Ref−G_A)/(L_Ref+G_B)*(L_User0+G_B)
• wherein DL_Int_Predict represents the loudness modification gain,
• L_EQ_Ref represents the loudness of the output audio signal which frequency band spectrum is corrected,
• L_Ref represents the desired loudness,
• G_A and G_B represents factors for adjusting the degree of correction of the loudness of the output audio signal which frequency band spectrum is corrected.