Patent ID: 7957973

Claim:
An audio signal interpolation method comprising: determining a spectral movement which is indicative of a difference in each of spectral components between a frequency spectrum of a current frame of an input audio signal and a frequency spectrum of a previous frame of the input audio signal stored in a spectrum storing unit; determining a frequency band which is to be interpolated, by using the frequency spectrum of the current frame and the spectral movement; and performing interpolation of spectral components in said frequency band for the current frame by using either the frequency spectrum of the current frame or the frequency spectrum of the previous frame, wherein an amount of movement of spectral components from the previous frame to the current frame is determined as being the spectral movement, and, when an amplitude of said spectral components is below a first threshold and a decrease of the amplitude of said spectral components from the previous frame to the current frame is above a second threshold, a frequency band of said spectral components is determined as being the frequency band which is to be interpolated.