表 2. Different frequency range of sub-band signals.
子带信号对应的不同频率范围
| 子带信号 | 频率范围/Hz |
| D1 | 32～64 |
| D2 | 16～32 |
| D3 | 8～16 |
| D4 | 4～8 |
| A4 | 0～4 |
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