One of the problems in spoken language translation is the enormous variety of expressions not found in text translation. This volume can lead to a sparse translation coverage. In order to tackle this problem, we take the practical approach of untangling slight variations in the source language before transferring a source expression to its target. We therefore discuss how eective paraphrasing is in the sense of reducing varieties in a spoken language, with a focus on how many source language patterns are reduced by paraphrasing. We also discuss the characteristics of the spoken Japanese by the paraphrasing patterns we obtain.