What if the most significant adverse changes humans have made to the planet aren't just visible, but also audible?

Cristina Costa
Jun 28
3 min read

A recent study about blue whales led me down an unexpected path. What began as a fascinating discovery about whale songs became a much broader reflection on communication, cities, audio, artificial intelligence, and the changing soundscape we all share. This is the connection I wasn't expecting.

I recently read a study that caught my attention. It reports that blue whales, the largest animals ever known to have lived on Earth, have been singing at progressively lower frequencies (pitch) has been declining over multi-decadal timescales, i.e., whales are producing songs at progressively for decades. Scientists have carefully measured this change, yet they still don't fully understand what is driving it. Several hypotheses have been proposed, including population recovery, changes in ocean conditions, and behavioural adaptation, but there is currently no definitive explanation. At first, it seems like a fascinating mystery about whales. But the more I read about the subject, the more I realized it may actually be a story about all of us.

Blue whales are not unique. During the COVID-19 lockdowns, researchers found that white-crowned sparrows around San Francisco no longer had to compete with traffic noise. They began singing more softly while producing more effective songs because the environment itself had become quieter. Other species respond differently. Some birds shift towards higher frequencies, bats adjust their echolocation, frogs change the timing or intensity of their calls, and some insects modify their vibration patterns. The strategy varies, but the goal remains the same: to keep communicating in an ever-changing acoustic environment.

But the transformation didn't happen only in nature. We have also profoundly reshaped the planet's soundscape. In little more than a century, we have filled it with engines, aircraft, trains, ventilation systems, factories, smartphones, and countless other sources of continuous noise. Soundscape ecology describes this acoustic world through three components: biophony, the sounds produced by living organisms; geophony, the sounds of wind, rain, rivers, and oceans; and anthrophony, the sounds generated by human activity. We rarely think of cities this way, yet they also occupy space in the acoustic spectrum.

That idea felt surprisingly familiar. Anyone working with audio spends a great deal of time trying to separate meaningful signals from background noise. Much of audio engineering is about improving the signal-to-noise ratio, reducing masking, increasing intelligibility, and preserving information. Nature has been solving exactly the same challenge for millions of years. Long before microphones, DSP, or AI, evolution was already optimizing communication in noisy environments.

Today we are entering another phase. The same artificial intelligence we use to develop audio products and media technologies is also learning to listen to forests, oceans, and cities. Acoustic monitoring systems can already distinguish animal sounds, natural phenomena, and human activity to study biodiversity and understand how ecosystems are changing. As these technologies continue to evolve, sound may become an increasingly valuable tool for understanding environmental change. I enjoy following developments across audio, science, and technology, but I wasn't expecting these fields to converge around something as simple—and as fundamental—as listening.

To me, that became the most interesting part of the story. We usually think of pollution as something we can see. But there is another form of pollution that occupies the acoustic spectrum itself. Every new sound we introduce changes the communication space available to other species. We are not the only animals communicating through sound. We may simply be the species that has reshaped Earth's soundscape more rapidly than any other.

I started reading about blue whales. I finished listening to the world around me a little more carefully.

Sources and Further Reading