1. A method for automatic speech recognition, wherein the method comprises: obtaining at least one language model word and at least one rule-based grammar word; determining an acoustic similarity of at least one pair of language model word and rule-based grammar word; and increasing a transition cost to the at least one language model word based on the acoustic similarity of the at least one language model word with the at least one rule-based grammar word to generate a modified language model for automatic speech recognition; wherein at least one of the steps is carried out by a computer device.