| 摘要 |
<p>A method for compression encoding of digital speech signals is provided in which the digital speech signals are divided at a predetermined time interval into plural frequency bands so as to be sub-divided along both the time scale and the frequency scale to form plural sub-blocks, and data encoding is performed using an allocation bit number determined for each of said sub-blocks. The total number of bits that may be used for bit allocation is divided into at least two portions, with the bits of one of theses portions being allocated in dependence upon the allowable noise level based on aural characteristics and with the bits of the remaining portion being allocated in dependence upon the intensities of signals in each sub-block. The number of bits allocated to each of the small-sized sub-blocks are determined by the sum of the bits of the two portions. In addition to the total number of bits that may be used for bit allocation, a number of bits can also be set for the subsidiary information at least including the floating information and the bit length information. The aural characteristics may be combined from at least the masking threshold and the minimum audibility curve and corrected by the equal-loudness curve. <IMAGE></p> |
