7. The speech synthesis information editing apparatus according to claim 1 , wherein the feature information specifies the feature for each of a plurality of editing points of the phonemes arranged on a time base, and the edition processing unit is configured to update the feature information such that a position of the editing point relative to a sounding interval of the phoneme is maintained before and after change of the duration of each phoneme.
7. The speech synthesis information editing apparatus according to claim 1 , wherein the feature information specifies the feature for each of a plurality of editing points of the phonemes arranged on a time base, and the edition processing unit is configured to update the feature information such that a position of the editing point relative to a sounding interval of the phoneme is maintained before and after change of the duration of each phoneme. 8. The speech synthesis information editing apparatus according to claim 7 , wherein the edition processing unit is configured to move a position of the editing point on the time base within the sounding interval of the phoneme represented by the phoneme information by an amount depending on a type of the phoneme when the time variation in the feature is updated.