The Sounds of the Mariana Trench

Eerie Whispers from the Abyss

Welcome back to the '1 in a million sounds' section, where we journey to the Earth's most extreme and mysterious places. Today, we're descending into the Mariana Trench, the deepest point in the world's oceans. At depths of nearly 11 kilometers (7 miles), where the pressure is over 1,000 times that of sea level, you might expect complete silence. Instead, an audio recording from this abyss reveals a surprisingly noisy, and often eerie, soundscape.

A Challenge to Record the Unheard

In 2015, a team of scientists from NOAA and Oregon State University undertook a remarkable mission. They deployed a specialized, titanium-encased hydrophone (underwater microphone) to the bottom of the Challenger Deep, the deepest point of the Mariana Trench. The hydrophone was built to withstand the immense pressure and recorded for 23 days straight. The recordings that came back shattered the expectation of a silent abyss and provided an unprecedented glimpse into this dark, unexplored world.

The Symphony of the Deep 🎶

The sounds captured were a mix of both natural and human-made noises, all traveling through the water column and echoing in the deep trench. The recordings included:

A Challenge to Record the Unheard

• Earthquakes: The most dominant natural sounds were the frequent rumbles and distant tremors of earthquakes, both near and far. These seismic activities create low-frequency waves that can travel vast distances through the ocean, making the trench a sort of global earthquake detector.

• Whale Calls: Scientists were astonished to record the distinct moans and songs of baleen whales, including a mysterious sound that has been a puzzle for years. In 2014, underwater gliders recorded a bizarre sound known as the "biotwang," which was a deep, low grumbling followed by a series of high-pitched, metallic-sounding pings. After years of analysis, including the use of AI, scientists have determined this sound is a contact call from a specific population of Bryde's whales.

• Human-made Noise: Even at the bottom of the world's deepest trench, the sounds of human activity were present. The recordings captured the rhythmic propeller sounds from ships on the surface, a full 7 miles above the hydrophone. This startling discovery highlights how far human noise pollution has permeated even the most remote parts of our planet's oceans.

• Weather Events: The hydrophone also picked up the low-frequency noise of a Category 4 typhoon as it passed miles away on the surface.

This audio recording is a profound one-in-a-million discovery. It proves that even in the most inhospitable and remote places on Earth, life and sound persist, challenging our assumptions about the deepest parts of our world. It's a haunting reminder of the connectivity of our planet, from the smallest tremors in the Earth's crust to the vast migration patterns of whales, and even the distant sounds of our own civilization.