10. A speech recognition apparatus comprising: a speech inputting unit configured to start input of speech made by a user in response to a user's operation; a determination unit configured to determine whether beginning of the input speech is missing; a setting unit configured to set pronunciation information for recognizing the input speech of which the beginning is not missing in a case where a head portion of a speech waveform power does not exceed a predetermined threshold value, and setting pronunciation information for recognizing the input speech of which the beginning is missing in a case where the head portion of the speech waveform power exceeds the predetermined threshold value; and a speech recognition unit configured to recognize the input speech using the set pronunciation information.
10. A speech recognition apparatus comprising: a speech inputting unit configured to start input of speech made by a user in response to a user's operation; a determination unit configured to determine whether beginning of the input speech is missing; a setting unit configured to set pronunciation information for recognizing the input speech of which the beginning is not missing in a case where a head portion of a speech waveform power does not exceed a predetermined threshold value, and setting pronunciation information for recognizing the input speech of which the beginning is missing in a case where the head portion of the speech waveform power exceeds the predetermined threshold value; and a speech recognition unit configured to recognize the input speech using the set pronunciation information. 11. The speech recognition apparatus according to claim 10 , wherein the determination whether the beginning of the input speech is missing in the determination unit is made using information about at least one of a zero-crossing rate, spectral information, and a feature parameter representing a harmonic structure.