Patent US 7,747,435

A speaker of encoded speech data recorded in a semiconductor storage device in an IC recorder is to be retrieved easily. An information receiving unit 10 in a speaker retrieval apparatus 1 reads out the encoded speech data recorded in a semiconductor storage device 107 in an IC recorder 100. A speech decoding unit 12 decodes the encoded speech data. A speaker frequency detection unit 13 discriminates the speaker based on a feature of the speech waveform decoded to find the frequency of conversation (frequency of occurrence) of the speaker in a preset time interval. A speaker frequency graph displaying unit 14 displays the speaker frequency on a picture as a two-dimensional graph having time and the frequency as two axes. A speech reproducing unit 16 reads out the portion of the encoded speech data corresponding to a time position or a time range specified by a reproducing position input unit 15 based on this two-dimensional graph from the storage device 11 and decodes the read-out data to output the decoded data to a speech outputting unit 17.