subvoice-grade channel

例句：

1. 1. The engineer used a subvoice-grade channel to transmit the data.
   工程师使用了一个次级声频通道来传输数据。
2. 2. The subvoice-grade channel was designed to improve audio quality.
   次级声频通道被设计用来提高音频质量。
3. 3. The subvoice-grade channel is essential for broadcasting in low-power environments.
   次级声频通道对于在低功率环境下的广播至关重要。