The present invention provides a method for processing audio signals, and the method comprises the steps of: receiving input audio signals corresponding to a plurality of spectral coefficients; obtaining location information that indicates a location of a particular spectral coefficient among said spectral coefficients, on the basis of energy of said input signals: generating a shape vector by using said location information and said spectral coefficients; determining a codebook index by searching for a codebook corresponding to said shape vector; and transmitting said codebook index and said location information, wherein said shape vector is generated by using a part which is selected from said spectral coefficients, and said selected part is selected on the basis of said location information.