Speech keyword spotting system and system and method of creating dictionary for the speech keyword spotting system

The application relates to a speech keyword spotting system comprising an input unit used for receiving input speech signals, a feature extracting unit used for extracting at least one feature from the input speech signals, a classifier unit used for classifying the input speech signals into target keywords or out-of-vocabulary based on at least one feature and a dictionary, and an output unit used for outputting the classification result. The dictionary comprises grammar and a lexicon, wherein the grammar comprises target keyword lists and at least one sequence used for two identifiers of the out-of-vocabulary; the lexicon comprises pronunciation representing all candidate keywords of speech subsequence of one or more target keywords in the target keyword lists, and pronunciation representing at least one sequence; and one identifier represents a first class of phone, while the other identifier represents a second class of phone. The first class of phone and the second class of phone are clustered based on inherent features of phones. The first class of phone, the second class of phone and the phones of one or more target keywords are described by models.