1. A method of recognizing a keyword in a speech, comprising: on an electronic device: receiving a sequence of audio frames comprising a current frame and a subsequent frame that follows the current frame; determining a candidate keyword for the current frame using a predetermined decoding network that comprises keywords and filler words of multiple languages, associating the audio frame sequence with a confidence score that is partially determined according to the candidate keyword; identifying a word option for the subsequent frame using the candidate keyword and the predetermined decoding network; when the candidate keyword and the word option are associated with two distinct types of languages, updating the confidence score of the audio frame sequence based on a penalty factor that is predetermined according to the two distinct types of languages, the word option and an acoustic model of the subsequent frame; and determining that the audio frame sequence includes both the candidate keyword and the word option by evaluating the updated confidence score according to a keyword determination criterion.