Thanks to the wonder of Google News customized daily news searches (in this case, “whales noise”), I came across a piece from the UK National Environment Research Council that raises a point I hadn’t considered before: as we develop undersea turbines to generate energy from tidal flows, the noise concern is not just whether it is too loud, but also whether it is loud enough.  An interview with bioacoustician Ben Wilson fleshes out this problem, which is, as root, that “they need to be noisy enough for sea creatures to avoid them but quiet enough to minimise noise pollution.”  The trick, and not a small one, will be that various species of fish, whales, and seals each hear very different frequencies of sound.
Listen to the interview here