10. The apparatus according to claim 9 , further comprising a shortening unit that shortens a reproduction time of the translated speech and the source speech by a length of a second difference computed by subtracting the first threshold time from the first difference, when the first difference is more than the first threshold time.
11. The apparatus according to claim 10 , wherein the shortening unit shortens the reproduction time of the translated speech and the source speech by increasing a reproduction speed.