1. A method for pre-processing a pronunciation dictionary for compression in a data processing device, the pronunciation dictionary comprising at least one entry, the entry comprising a sequence of character units and a sequence of phoneme units, the method comprising: aligning said sequence of character units and said sequence of phoneme units using a statistical algorithm; and interleaving said aligned sequence of character units and said aligned sequence of phoneme units by inserting each phoneme unit at a predetermined location relative to the corresponding character unit.