Patent ID: 8359196

Claim:
A stereo speech decoding apparatus, comprising: a monaural decoding section that decodes monaural encoded data to generate a monaural decoded signal, the monaural encoded data encoding in a speech encoding apparatus a monaural signal acquired using an addition of a first channel signal and second channel signal; a stereo decoding section that decodes side signal encoded data to generate a side decoded signal, and generates a stereo decoded signal comprised of a first channel decoded signal and second channel decoded signal using the monaural decoded signal and the side decoded signal, the side signal encoded data encoding in the speech encoding apparatus a side signal acquired using a difference between the first channel signal and the second channel signal; a comparison section that compares a comparison threshold with an inter-channel correlation and intra-channel correlation calculated using a monaural decoded signal of a past frame and a stereo decoded signal of the past frame; an inter-channel concealment section that performs an inter-channel concealment using the monaural decoded signal of a current frame and the stereo decoded signal of the past frame, and generates an inter-channel concealed signal; an intra-channel concealment section that performs an intra-channel concealment using the monaural decoded signal of the current frame and the stereo decoded signal of the past frame, and generates an intra-channel concealed signal; a concealed signal selecting section that selects one of the inter-channel concealed signal and the intra-channel concealed signal, as a concealed signal, based on a comparison result in the comparison section; and an output signal switching section that outputs the stereo decoded signal when the side signal encoded data of the current frame is not lost, and outputs the concealed signal when the side signal encoded data of the current frame is lost.