15. An information retrieval system comprising: a speech input unit for inputting speech; an information storage unit for storing information with which speech information, of a length with which text degree of similarity is computable, is associated as a retrieval tag; an information selection unit for comparing a feature of each spoken content item extracted from each item of said speech information, with a feature of spoken content extracted from said input speech, to select information with which speech information similar to input speech is associated; an output unit for outputting information selected by said information selection unit, as information associated with input speech; a speech recognition unit for converting a speech signal into text data; a degree of similarity computation unit for computing degree of similarity between two or more speech recognition results generated by said speech recognition unit; and an information registration unit for registering a speech recognition result obtained by said speech recognition unit or a text feature vector generated from said speech recognition result, as said speech information associated with information that is to be retrieved, in said information storage unit; wherein, speech recognition of each of a speech signal stored as said speech information in said information storage unit and said input speech is performed by said speech recognition unit, respectively; degree of similarity between each of said speech recognition results is computed by said degree of similarity computation unit; and said information selection unit selects information with which speech information having a high degree of similarity to input speech is associated, based on degree of similarity computed by said degree of similarity computation unit.
15. An information retrieval system comprising: a speech input unit for inputting speech; an information storage unit for storing information with which speech information, of a length with which text degree of similarity is computable, is associated as a retrieval tag; an information selection unit for comparing a feature of each spoken content item extracted from each item of said speech information, with a feature of spoken content extracted from said input speech, to select information with which speech information similar to input speech is associated; an output unit for outputting information selected by said information selection unit, as information associated with input speech; a speech recognition unit for converting a speech signal into text data; a degree of similarity computation unit for computing degree of similarity between two or more speech recognition results generated by said speech recognition unit; and an information registration unit for registering a speech recognition result obtained by said speech recognition unit or a text feature vector generated from said speech recognition result, as said speech information associated with information that is to be retrieved, in said information storage unit; wherein, speech recognition of each of a speech signal stored as said speech information in said information storage unit and said input speech is performed by said speech recognition unit, respectively; degree of similarity between each of said speech recognition results is computed by said degree of similarity computation unit; and said information selection unit selects information with which speech information having a high degree of similarity to input speech is associated, based on degree of similarity computed by said degree of similarity computation unit. 16. The information retrieval system according to claim 15 , further comprising: a text feature vector generation unit for computing a text feature vector from a speech recognition result generated by said speech recognition unit wherein said degree of similarity computation unit is further to compute degree of similarity between two or more text feature vectors computed by said text feature vector generation unit; wherein, after performing speech recognition of each of said input speech and a speech signal stored as speech information in said information storage unit by said speech recognition unit, text feature vectors of each thereof are computed by said text feature vector generation unit, degree of similarity between each of said text feature vectors is computed by said degree of similarity computation unit; and said information selection unit selects information with which speech information having a high degree of similarity to input speech is associated, based on degree of similarity computed by said degree of similarity computation unit.