7. The method of claim 6 further comprising selecting the subset of speakers from the speaker pool based on a similarity score determined from the speaker pool means and the adapted means.
7. The method of claim 6 further comprising selecting the subset of speakers from the speaker pool based on a similarity score determined from the speaker pool means and the adapted means. 8. The method of claim 7 further comprising: forming training means for each of the plurality of mixture components by adapting the background model based on a training speech signal from a user; and determining nominal user thresholds based on speaker pool means for a second subset of the speakers in the speaker pool, the second subset being selected from the speaker pool based on a similarity score determined from the speaker pool means and the training means.