17. Method as claimed in claim 15, further comprising the steps of: expanding each said reference template into a first expanded reference template and a second expanded reference template, the values of said first expanded reference template representing the probability of a binary one occurring in the corresponding position of said utterance template and the values of said second expanded reference template representing the probability of a binary zero occurring at said corresponding position of said utterance template; and expanding said bias template into a first expanded bias template and a second expanded bias template, the values of said first expanded bias template representing the probability of a binary one occurring in the corresponding position of any said utterance template and the values of said second expanded bias template representing the probability of a binary zero occurring at said corresponding position of any said utterance template.
17. Method as claimed in claim 15, further comprising the steps of: expanding each said reference template into a first expanded reference template and a second expanded reference template, the values of said first expanded reference template representing the probability of a binary one occurring in the corresponding position of said utterance template and the values of said second expanded reference template representing the probability of a binary zero occurring at said corresponding position of said utterance template; and expanding said bias template into a first expanded bias template and a second expanded bias template, the values of said first expanded bias template representing the probability of a binary one occurring in the corresponding position of any said utterance template and the values of said second expanded bias template representing the probability of a binary zero occurring at said corresponding position of any said utterance template. 18. Method as claimed in claim 17 wherein said first score establishing step includes: selecting for each position of the expanded reference templates either the output from said first expanded reference template if the corresponding position in the utterance template contains a binary one or the output from said second expanded reference template if the corresponding position in the utterance template contains a binary zero for scoring each reference template.