We tried to construct a system in which we can enquire unknown words, included in TV news speech by repeating them spontaneously. For example, we hear "Japan would join PKO." from TV news and if "PKO" is an unknown word, then we can enquire it by saying "What's the PKO?" The system recognizes the word "PKO" and explains its meaning. In this system, it estimates a common section between announcer's speech and user speech, and recognizes the word corresponding to the common section. We solved a problem of speaker difference in extracting common sections by speaker subspace projection.