A method for processing an audio signal, comprising: receiving a spectral data of lower band and type information indicating a particular band extension scheme for a current frame of the audio signal from among a plurality of band extension schemes including a first band extension scheme and a second band extension scheme, by an audio processing apparatus; when the type information indicates the first band extension scheme for the current frame, generating a spectral data of higher band in the current frame using the spectral data of lower band by performing the first band extension scheme including bandpass filtering, time stretching processing and decimation processing; and when the type information indicates the second band extension scheme for the current frame, generating the spectral data of higher band in the current frame using the spectral data of lower band by performing the second band extension scheme, wherein: the second band extension scheme is based on a first data area of the spectral data of lower band, the first band extension scheme is based on a second data area of the spectral data of lower band, the first data area is greater than the second data area, the second data area is a portion of the spectral data of lower band, the first data area is one of all and a plurality of portions including the portion of the spectral data of lower band, the higher band comprises at least one band equal to or higher than a boundary frequency and wherein the lower band comprises at least one band equal to or lower than the boundary frequency, and wherein application of the first band extension scheme or the second band extension scheme on the current frame is temporarily determined based on a coding scheme of the audio signal, and application of the first band extension scheme or the second band extension scheme on the current frame is finally determined based on whether the audio signal is in a transient interval. receiving a spectral data of lower band and type information indicating a particular band extension scheme for a current frame of the audio signal from among a plurality of band extension schemes including a first band extension scheme and a second band extension scheme, by an audio processing apparatus; when the type information indicates the first band extension scheme for the current frame, generating a spectral data of higher band in the current frame using the spectral data of lower band by performing the first band extension scheme including bandpass filtering, time stretching processing and decimation processing; and when the type information indicates the second band extension scheme for the current frame, generating the spectral data of higher band in the current frame using the spectral data of lower band by performing the second band extension scheme, wherein: the second band extension scheme is based on a first data area of the spectral data of lower band, the first band extension scheme is based on a second data area of the spectral data of lower band, the first data area is greater than the second data area, the second data area is a portion of the spectral data of lower band, the first data area is one of all and a plurality of portions including the portion of the spectral data of lower band, the higher band comprises at least one band equal to or higher than a boundary frequency and wherein the lower band comprises at least one band equal to or lower than the boundary frequency, and wherein application of the first band extension scheme or the second band extension scheme on the current frame is temporarily determined based on a coding scheme of the audio signal, and application of the first band extension scheme or the second band extension scheme on the current frame is finally determined based on whether the audio signal is in a transient interval. the second band extension scheme is based on a first data area of the spectral data of lower band, the first band extension scheme is based on a second data area of the spectral data of lower band, the first data area is greater than the second data area, the second data area is a portion of the spectral data of lower band, the first data area is one of all and a plurality of portions including the portion of the spectral data of lower band, the higher band comprises at least one band equal to or higher than a boundary frequency and wherein the lower band comprises at least one band equal to or lower than the boundary frequency, and wherein application of the first band extension scheme or the second band extension scheme on the current frame is temporarily determined based on a coding scheme of the audio signal, and application of the first band extension scheme or the second band extension scheme on the current frame is finally determined based on whether the audio signal is in a transient interval.