Blue whales, the largest animals on Earth, are known for their immense size, but they also possess a remarkable ability to produce some of the loudest sounds in the animal kingdom. These powerful vocalizations play a central role in their lives, allowing them to interact across vast stretches of the ocean. The unique characteristics of their calls and how they travel through water are key to understanding the communication networks of these marine giants.
Measuring Blue Whale Call Loudness
Blue whale calls are loud, with recorded measurements often reaching 180 to 188 decibels (dB) in water. These low-frequency sounds, often below the range of human hearing, are among the most intense biological noises generated by any creature on Earth. Sound measurement in water uses a different reference pressure than in air, making direct comparisons to sounds in air not straightforward.
Understanding the Scale of Loudness
To put the loudness of a blue whale’s call into perspective, a jet engine at takeoff is approximately 140 decibels. Blue whale vocalizations can exceed this. While sperm whales produce louder, short clicks (up to 230 decibels), blue whale calls are sustained vocalizations. Human hearing is protected from these extreme underwater sounds because our ears are not adapted for the different properties of sound in water.
Why Blue Whale Calls Are So Loud
The loudness of blue whale calls serves several biological functions in the vast ocean environment. These powerful, low-frequency vocalizations are primarily used for long-distance communication, enabling whales to find mates across wide expanses of water. They also use these calls for navigation, potentially by listening to echoes bouncing off distant underwater features. Producing such loud sounds helps blue whales overcome the background noise present in the ocean, ensuring their messages can be heard clearly by other whales.
How Blue Whale Calls Travel Through Water
Sound travels faster and farther in water than in air due to water’s higher density. In seawater, sound travels at approximately 1,500 meters per second, more than four times faster than its speed in air. This property allows blue whale calls to propagate over immense distances.
A primary factor in this long-range transmission is the “SOFAR channel” (Sound Fixing and Ranging channel), a layer in the ocean where the speed of sound is at its minimum. This channel acts like a natural waveguide, trapping low-frequency sounds and allowing them to travel thousands of miles with minimal energy loss. Blue whale calls can be detected by other whales up to 1,000 miles away under favorable conditions, demonstrating the effectiveness of this underwater sound highway.