1. A prosody-pattern generating apparatus comprising: an initial-prosody-pattern generating unit that generates an initial prosody pattern based on language information and a prosody model which is obtained by modeling prosody information in units of phonemes, syllables and words that constitute speech data; a normalization-parameter generating unit that generates, as normalization parameters, mean values and standard deviations of the initial prosody pattern and a prosody pattern of a training sentence included in a speech corpus, respectively; a normalization-parameter storing unit that stores the normalization parameters; and a prosody-pattern normalizing unit that normalizes a variance range or a variance width of the initial prosody pattern, bringing the variance range or the variance width of the initial prosody pattern to the same level as a variance range or a variance width of the prosody pattern of the training sentence in the speech corpus in accordance with the normalization parameters.