| 摘要 |
PROBLEM TO BE SOLVED: To suppress distortion in reproduced voice signals and to reduce the amount of complex processes by assigning the number of bits, that are beforehand assigned, to a sub-band(SB) in a bit assigning process when the level of voice data in the SB is smaller than a masking threshold value and the difference between the level and the value is less than a beforehand set value. SOLUTION: A level comparing section 106 compares the level of quantization noise generated while requantizing voice data by the assigned number of bits to each SB with the masking threshold value. Moreover, a comparison is made between the difference between the signal level in each SB and the level of the masking threshold value and a reference value that is beforehand determined. Then, the comparison result is transmitted to a bit allocation section 103. Based on the result of the comparison, the section 103 determines the number of bits assigned to each SB. By assigning a minimum number of bits to an SB, distortion in reproduced voice signals is suppressed and the amount of complex processes is reduced. |
