On Cosmic Sound, Animal Intelligence, and
What Happens When We Make Less Noise
In September 2015, two black holes that had been orbiting each other for a billion years finally collided. The event released fifty times more energy than every star in the observable universe combined. It took a fraction of a second. And it made a sound. Not in any poetic sense but a literal sound, a pressure wave propagating through the fabric of spacetime itself. When the signal reached the LIGO detector in Louisiana, it registered as a chirp: a rising frequency sweep lasting less than a second, like a bird call compressed into a heartbeat. The LIGO spokesperson announced it with words that deserve to be remembered: “We can hear gravitational waves. We are not only going to be seeing the universe, we are going to be listening to it.”
That chirp was the sound of two black holes, each thirty times the mass of the sun, merging 1.3 billion light-years away. We heard it. The question worth asking is: what else are we not hearing?
The Big Bang was not an explosion into silence. In the first 380,000 years of the universe’s existence, before atoms could even form, the cosmos was a dense hot plasma thick enough to carry acoustic waves. Pressure waves rippled through this primordial medium for hundreds of thousands of years. When the universe cooled and matter decoupled from radiation, those waves froze in place. Their pattern is still visible today not as sound, but as a statistical regularity in the distribution of galaxies across hundreds of millions of light-years. Cosmologists call it Baryon Acoustic Oscillation. It is, effectively, a fossil of the universe’s first sound.
NASA has recorded a contemporary version: pressure waves moving through the hot gas of the Perseus galaxy cluster, 57 octaves below the threshold of human hearing. Real waves, real pressure, real propagation just at a frequency we have no biological equipment to detect. This is the baseline condition. The universe emits. We have almost no capacity to receive.
Other species have built what we have not. Some baleen whale species call at frequencies so deep that killer whales, their primary predator, cannot hear them. Below 100 Hz, orcas are acoustically deaf. The great whales communicate in a register that is, to the animal most dangerous to them, silence.
Blue whales produce sounds as low as 10 Hz. They navigate ocean basins using these calls, bouncing frequencies off underwater terrain, reading the deep-sea sound channel that forms around 1,000 metres depth where pressure, temperature, and salinity converge to trap and carry low-frequency sound across thousands of kilometres. A blue whale singing off Sri Lanka can, in principle, be heard by another whale near the Azores. The ocean, to them, is not a medium they move through. It is a continuous acoustic field they read. They appear to cross-reference this with Earth’s magnetic field as a map, and may also be listening to infrasound from snapping shrimp aggregations near coastlines using biological sound to detect land the way a radar operator reads a return signal. Navigation as acoustic perception.
Elephants operate at a different register. They communicate across hundreds of kilometres at 14 to 16 Hz, below the human hearing floor of 20 Hz and they do not only hear infrasound, they feel it. Their skeleton acts as a receiver, transmitting ground vibrations upward through the pads of their feet. Elephant matriarchs have been observed changing herd direction in response to infrasonic signals, probably from distant thunder, approaching herds, or seismic tremor, before any environmental change becomes visible or audible to human observers. They are reading the landscape through the ground.
Pigeons are stranger still. They can detect infrasound as low as 0.05 Hz, a frequency at which pressure changes happen roughly once every twenty seconds. The hypothesis gaining traction is that pigeons navigate using an infrasound direction-finding system analogous to maritime radio direction-finding: geological features, coastlines, and mountain ranges emit infrasound that propagates over vast distances, and pigeons may be using it as a continuous positional fix. Their navigational precision, long attributed to magnetic sensing or olfactory mapping, may be partly acoustic.
All of this intelligence is functional, encoded, and acted upon. These animals are processing information from the physical world that we have no sensory access to. They did not acquire these capabilities recently. They evolved them over millions of years because the information was there to be used, at frequencies the physical environment generates continuously and reliably. We are the outlier, the species that hears a narrow band of the acoustic spectrum and has organised its entire understanding of communication around that band, largely unaware of what falls outside it.
Until recently, studying any of this at scale was nearly impossible. Three shifts changed this simultaneously. First, sensors became cheap enough to deploy in arrays. Acoustic monitors that once cost thousands of dollars per unit can now be networked across ecosystems. The emerging field of eco-acoustics uses these networks to monitor entire soundscapes — not individual species but the acoustic signature of ecosystem health. A healthy tropical forest sounds different from a degraded one. Ecological stress can now be detected acoustically before it becomes visible.
Second, machine learning made the data legible in ways that will take years to fully absorb. In 2024, a team of marine biologists, linguists, cryptographers, and AI researchers announced a significant finding: sperm whale clicks, called codas, have combinatorial structure, an alphabet with what appear to be vowel-like elements and contextual variation that the team is mapping using transformer models trained on years of recordings from a monitored whale population off Dominica. The same architecture that powers large language models is being turned on sperm whale communication, looking for syntax, context, and meaning. Whether what emerges constitutes language in any meaningful sense remains genuinely open. What is no longer open is whether their communication has structure. It does.
Third, gravitational wave astronomy opened a new sensory modality entirely. LIGO’s observing runs have now catalogued dozens of merger events. Researchers at the Max Planck Institute for Gravitational Physics and TIFR Bangalore have proposed that third-generation detectors, the planned Einstein Telescope and Cosmic Explorer, could detect Baryon Acoustic Oscillations directly through gravitational wave observations, providing an independent cosmological probe. We are building instruments that can hear the structure of the universe itself. The question that follows from this is not technical. It is perceptual: if the universe has been speaking at frequencies we could not hear, and we are now beginning to hear them, what does that imply about all the other frequencies we have not yet thought to listen for?
Against this backdrop, the noise we produce looks different than it did. Not primarily as a health problem but as a perceptual one. We are jamming the frequencies on which other species have built their entire cognitive architecture, and we are simultaneously saturating our own.
For marine life, the interference is operating where it does the most damage. Anthropogenic ocean noise, shipping, sonar, seismic surveys, offshore drilling, occupies the same frequencies that whales use to navigate, communicate, and hunt. The deep-sea acoustic channel that blue whales evolved to exploit over millions of years is now partially occupied by the noise of global trade. We moved into their frequency without knowing it was inhabited.
On land, the picture is less dramatic but equally serious. Low-flying aircraft near natural reserves disrupts infrasound-sensitive animals, elephants, certain raptors, in ways that remain poorly quantified but are almost certainly significant given what we now know about how they use infrasound. Urban expansion has raised infrasonic noise floors across vast areas, reducing the signal-to-noise ratio in the acoustic environment that many species use for orientation and threat detection. What navigational or communicative intelligence is being lost as that environment degrades is not yet known. But the question is no longer speculative. It is being seriously asked, with instruments capable of providing answers.
The human dimension is less visible because we do not perceive ourselves as acoustic creatures in the way whales clearly are. We should. The average person in an urban environment now spends seven to eight hours per day with audio in their ears — music, podcasts, calls, notifications — in addition to ambient noise from traffic, construction, and machinery. The brain’s default mode network, which activates during genuine quiet and is associated with memory consolidation, creative insight, and self-referential processing, is chronically underused. This network does not activate during passive consumption of audio. It requires actual silence. And the cognitive work it performs, the kind of slow, associative, pattern-recognition thinking that generates insight rather than reaction, cannot be substituted by processing more information faster.
This is where the two strands of this essay converge into a single point. The faculty we would need to cultivate to perceive more to notice subtle signals, to hold complexity without collapsing it into noise, to think at the low frequencies where the most important patterns are is precisely the faculty that constant stimulation degrades. We are building instruments of extraordinary sensitivity to hear the universe at new frequencies. And we are simultaneously degrading our own capacity for exactly the kind of quiet, patient attention that receiving new information requires. LIGO works because it is isolated from vibration, shielded from interference, built in conditions of extraordinary stillness. We are doing the opposite to ourselves.
Contemplative traditions across cultures arrived at this independently, without neuroscience to explain it: that perception requires stillness, that the loudest voice in the room is rarely the most important one, that genuine intelligence, not information processing but actual understanding, emerges in quiet. This is not mysticism. It maps onto what we now know about the default mode network, about how the brain processes weak signals, about the documented physiological responses to low-frequency sound that humans experience below the threshold of conscious hearing. The traditions were describing something real. They simply did not have the instruments to show why.
There are practical things that reduce the damage. Noise barriers in schools produce measurable improvements in children’s cognitive performance. Quiet zones around wildlife corridors reduce stress indicators in sensitive species. Slower shipping speeds and better hull design demonstrably reduce acoustic interference in whale habitat. These are not expensive interventions. They are not being made at anything like the scale the evidence warrants, partly because sound remains invisible as a regulatory category in a way that air and water quality are not, and partly because the health and ecological case has not yet been connected to the larger perceptual argument that would give it its real urgency.
That argument is this: we are living through the most significant expansion of our sensory reach in human history. We can hear black holes collide. We can detect the fossil sound of the universe’s first moments. We are beginning to decode the structured communication of species whose acoustic intelligence makes ours look narrow. And we are doing all of this while filling every available frequency with our own noise eroding the acoustic environments on which other species’ cognition depends, and degrading in ourselves the very capacity for quiet attention that receiving new information requires. We built LIGO because we suspected the universe was speaking at frequencies we could not naturally hear, and we were right. The next step, harder because it requires restraint rather than construction, is to ask what we might hear if we stopped talking long enough to listen.