Although blind source extraction is advantageous over blind signal separation in practical applications, it is difficult to choose the extracted source from many sources in the mixtures. A new algorithm is presented to extract a source signal of shorter source-to-microphone distance from two convolutive mixtures. The developed algorithm imposes an additional constraint on the extracting filters, i.e. high direct-to-reverberation ratio. In experiments, the algorithm successfully extracted the shorter-distance signal even though the interference was much stronger for both simulated convolutive mixtures and real-recorded mixtures in an office room.