This guys is completely wrong about the noise issue. It is not the just the frequency of the noise it is also the depth of the source of noise. The lower the frequency the farther and deeper it travels in the water (that's how nuclear submarines communicate around the world without surfacing).
Large ships have their engines sometimes 30-40 ft. underwater as well as multiple higher frequency generators (especially cruise ships). Lots of information and studies done by the navy show that small craft engines have little impact on Orcas (that why they can swim up to and around our boats) as the higher frequencies don't penetrate down into the water column that much or far due to thermoclines, water density, salinity, etc. as much as lower frequencies that originate deeper in the water from large shipping. The sonar from our depth sounders have more impact than our small engines noises - that's why we should turn off our sonar and slowly exit an area when the orcas are around.
