22. A prosody generation apparatus that receives phonological information and linguistic information so as to generate prosody, the prosody generation apparatus being operable to refer to (a) a representative prosodic pattern storage unit for accumulating beforehand representative prosodic patterns of portions of speech data, the portions including prosody changing points; (b) a selection rule storage unit that stores a selection rule predetermined according to attributes concerning phonology or attributes concerning linguistic information of the portions of the speech data including the prosody changing points; and (c) a transformation rule storage unit that stores a transformation rule predetermined according to attributes concerning the phonology or the linguistic information of the portions of the speech data including the prosody changing points; the prosody generation apparatus comprising a computer processing unit and a memory storing a program that are configured to implement: a prosody changing point setting unit that sets a prosody changing point according to at least any one of the received phonological information and the linguistic information; a pattern selection unit that selects a representative prosodic pattern from the representative prosodic pattern storage unit according to the selection rule, based on the received phonological information and the linguistic information; and a prosody generation unit that transforms the representative prosodic pattern selected by the pattern selection unit according to the transformation rule and interpolates the transformed prosodic pattern for a portion between the prosodic patterns corresponding to the prosody changing points, wherein the transformation rule is obtained by clustering prosodic patterns of the speech data into clusters corresponding to the representative patterns so as to produce a representative pattern for each cluster and by formulating a relationship between (i) a distance between each of the prosodic patterns and a representative pattern of a cluster to which the prosodic pattern belongs and (ii) attributes concerning phonology or attributes concerning linguistic information of the prosodic pattern, by means of a statistical technique or a learning technique so as to estimate an amount of transformation of the selected prosodic pattern, using at least one of the attributes concerning phonology and the attributes concerning linguistic information.
23. The prosody generation apparatus according to claim 22 , wherein the amount of transformation is one of a shifting amount, a compression rate in a dynamic range and an extension rate in a dynamic range.