There are provided a search method of a fixed codebook, and more
particularly, a focused search method and apparatus thereof, for being
applied to a speech codec for Voice over Internet Protocol (VoIP). The
focused search method of the fixed codebook includes: calculating
absolute values of correlation vectors of respective pulse locations of
tracks 0, 1, 2, and 3 and arranging the pulse locations in a descending
order of the absolute values; and selecting a predetermined number of
pulse locations for each track among candidate pulse locations arranged
and conducting focused search of the selected result. Therefore, it is
possible to significantly reduce a calculation amount required for fixed
codebook search while maintaining tone quality in a similar level.