Compressed Ship Noise

Ship noise

This 2.5-minute clip plays at 5x normal speed, raising the pitch you hear. Other sound qualities are unchanged.

Sifting through acoustic smog

Detecting right whales would be easier if they would just swim up to the buoys and sing into the hydrophone. But more often the sounds come from miles away and are buried in background noise. Christopher W. Clark, Senior Scientist in the Bioacoustics Research Program, describes this continual din as “acoustic smog.” Here’s an example: the sound of a ship passing by a recorder.

A ship traveling at 10 knots takes an hour to traverse an auto-detection buoy’s 10-nautical-mile-wide listening area. The noise is merely annoying for human analysts, but for right whales it’s a constant assault on their eardrums.

Low, rising sounds that are close in pitch to a right whale’s call can trigger the auto-detection software. Most of these noises turn out to be ships or other machinery. For example, the ship noise above contains ascending pitches (center right in the graph) that a computer could mistake for a right whale.

What do we sound like to the whales

What Do We Sound Like to a Whale?

By Multimedia Productions, Cornell Lab of Ornithology. Complete credit.

What do we sound like to a whale?

Whale songs fill the ocean with soothing notes and peaceful rhythms. Our sounds are a lot more jarring.

Click the player at left to take an underwater audio tour of Massachusetts Bay.