13. An apparatus for training a duration prediction model, comprising: an initial model generator configured to generate an initial duration prediction model with a plurality of attributes related to duration prediction and at least part of possible attribute combinations of said plurality of attributes, in which each of said plurality of attributes and said attribute combinations is included as an item; an importance calculator configured to calculate importance of each said item in said duration prediction model; an item deleting unit configured to delete the item having a lowest importance calculated; a model re-generator configured to re-generate a duration prediction model with remaining items after a deletion of said item deleting unit; and an optimization determining unit configured to determine whether said duration prediction model re-generated by said model re-generator is an optimal model.
13. An apparatus for training a duration prediction model, comprising: an initial model generator configured to generate an initial duration prediction model with a plurality of attributes related to duration prediction and at least part of possible attribute combinations of said plurality of attributes, in which each of said plurality of attributes and said attribute combinations is included as an item; an importance calculator configured to calculate importance of each said item in said duration prediction model; an item deleting unit configured to delete the item having a lowest importance calculated; a model re-generator configured to re-generate a duration prediction model with remaining items after a deletion of said item deleting unit; and an optimization determining unit configured to determine whether said duration prediction model re-generated by said model re-generator is an optimal model. 19. The apparatus for training a duration prediction model according to any one of claims 13 - 18 , wherein said plurality of attributes related to duration prediction further include speaking rate.