PURPOSE: An audio signal processing method and an apparatus thereof are provided to minimize cognitive distortion under the low bit rate environment by adjusting masking threshold level based on relation between the sensitivity of the extent of the energy and the quantization noise. CONSTITUTION: The frequency spectrum is generated by frequency-modulating the audio signal(S110). Each bandwidth weighted value for each bandwidth energy is determined by using the frequency spectrum(S120). The masking threshold level according to the psycho acoustic model is received(S140). The transformed masking threshold level is generated by applying the weighted value to the masking threshold level(S160). The signal is quantized by using the transformed masking threshold level.
A METHOD AND APPARATUS FOR PROCESSING AN AUDIO SIGNAL