Patent Document ID: 6061648
Application ID: 09030910

Base Claim:
1. An apparatus for coding a speech signal, comprising: an input device that inputs a mixed speech signal of a plurality of speakers; a separating device that analyzes period characteristics of the input mixed speech signal entered by said input device, and separates the input mixed speech signal into a plurality of single speech signals each associated with a corresponding one of the plurality of speakers, based on a result of the analysis; a first extracting device that extracts source speech characteristic parameters included in each of the single speech signals derived by said separating device, said source speech characteristic parameters representing characteristics of source speech generated from vocal cords of each of the speakers; a second extracting device that extracts a generic vocal-tract characteristic parameter from the input mixed speech signal, said generic vocal-tract characteristic parameter representing a vocal-tract characteristic shared by the plurality of speakers; and an output device that outputs the source speech characteristic parameters extracted by said first extracting device, and the vocal-tract characteristic parameter extracted by said second extracting device.

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Claim 4:
4. An apparatus as claimed in claim 1, wherein said separating device and said first extracting device comprise a vocal-tract filter that filters the input mixed speech signal based on said generic vocal-tract characteristic parameter to remove vocal-tract characteristics from the input speech signal to thereby generate a single source speech signal, a cross-correlation operating device that determines one of said source speech characteristic parameters, based on cross-correlation between said single source speech signal and a single source speech signal previously obtained, and a decoder that generates each of the single speech signals associated with a corresponding one of the plurality of speakers, based on the determined source speech characteristic parameter.