Acoustic Architecture.

In the ocean, light is a local luxury, but sound is a global medium. Through a trick of physics, the deep sea contains a "hallway" that can carry a whale’s voice across an entire hemisphere.

The speed of sound in water is determined by two factors: temperature and pressure. Near the surface, the water is warm, making sound move fast. In the deep abyss, the high pressure also makes sound move fast. But in between, at a depth of about 600 to 1,200 meters, there is a "sweet spot" where sound moves at its absolute minimum speed.

The SOFAR Channel

This is the Sound Fixing and Ranging (SOFAR) channel. Because sound waves always bend toward the region where they move slowest (a process called refraction), the SOFAR channel acts as a biological waveguide. Any low-frequency sound produced within this layer gets trapped, bouncing between the warmer water above and the high-pressure water below.

Global Conversations

Blue whales and Fin whales utilize this architecture to communicate over vast distances. By diving into the SOFAR channel, their low-frequency moans can travel for thousands of miles without losing significant energy. Before the advent of human shipping noise, it is estimated that a whale in the Caribbean could potentially have been heard by a whale off the coast of Africa.

The Anthropogenic Shadow

Today, this ancient acoustic highway is under threat. The SOFAR channel is increasingly crowded with the noise of container ships, sonar, and oil exploration. This "acoustic smog" masks the frequencies used by marine life, shrinking their communication range from thousands of miles down to just dozens—effectively isolating global populations that have been connected for millions of years.