Patent ID: 8140324

Claim:
A method of encoding a high-frequency subband of a speech signal having a low-frequency subband and the high-frequency subband, said method comprising: within a device that is configured to process audio signals, filtering the speech signal to obtain the low-frequency subband and the high-frequency subband; within the device, and based on information from the obtained high-frequency subband, calculating a plurality of filter parameters that characterize a spectral envelope of the high-frequency subband; within the device, calculating a spectrally extended signal by extending the spectrum of an excitation signal derived from the low-frequency subband; within the device, generating a synthesized highband signal according to (A) a highband excitation signal based on the spectrally extended signal and (B) the plurality of filter parameters; and within the device, calculating a gain envelope by evaluating a relation between the high-frequency subband and a signal based on the excitation signal derived from the low-frequency subband.