| 摘要 |
PURPOSE:To minimize the degradation in tone quality regardless of a low bit rate by setting the allowable noise level for the same energy to a higher value in the case of a higher frequency by a noise level setting means. CONSTITUTION:A total sum detecting circuit 14 and a filter circuit 15 as the noise level setting means which sets the allowable noise level of each band unit based on the energy (or the peak value and the average value) of each of critical bands and a quantizing circuit 24 which quantizes components of each band with the number of bits assigned in accordance with the energy of each band and the level of the difference of the noise level setting means are provided. The allowable noise level for the same energy is set to a higher value in the case of the critical band having a higher frequency by the noise level setting means. Thus, the degradation in tone quality is minimized to reduce the bit rate. |
