1. A language independent speech recognition system comprising: a. a speech pre-processor which receives input speech and produces a speech-related signal representative of the input speech; b. a database of acoustic hidden Markov models which represent subword units in each of a plurality of languages, wherein any subword unit that is common to two or more of the plurality of languages is represented by a single common acoustic hidden Markov model; c. a language model which characterizes a vocabulary of recognizable words and a set of grammar rules; and d. a speech recognizer which compares the speech-related signal to the acoustic hidden Markov models and the language model, and recognizes the input speech as a specific word sequence of at least one word.