1. A method for automatic speech recognition, the method comprising: receiving a frame of a speech signal; expanding, by a processor, a search network based on the frame; determining, by the processor, a best hypothesis in the search network; modifying, by the processor, a beam threshold based on a time the frame was received to produce a modified beam threshold, wherein modifying a beam threshold further comprises modifying the beam threshold based on a speed with which the search network is increasing in size; and pruning, by the processor, the search network using the best hypothesis and the modified beam threshold.