For one thing, they're reliable and sofar as they're based on unbiased samples.

首先，如若基于无偏样本，那么这些刻板印象就很可靠。

They can do this thanks to the SOFAR channel, or Deep Sea Channel, that generally starts at 1, 970 ft, but can vary in depth.

长须鲸能发出这样的声音，要归功于深海低频声学通道，即深海通道，一般从 1970 英尺处开始，但根据深度变化可能会有所不同。