When comparing our hearing acuity to other animals, we
can’t come close when it comes to detecting certain high and
low sounds. Bats and some toothed whale species echolocate
using high frequencies we can’t even begin to hear. They do
this by sending out loud, short bursts of precisely targeted
sound in ranges where the return echoes provide an acoustic
snapshot of the target prey. The return signal instantly
reveals all the information bats need in order to decide whether the targets are worth expending the energy to
pursue. Then there’s the greater wax moth, which can hear
frequencies as high as 300kHz.
For you musicians reading this, that’s about six and a
half octaves higher than the highest note on a piano and
about four times higher than a young child with the full
human range of hearing can detect. The ability of these
animals to accurately target and process the information
they receive gives new meaning to the term
In one lab test done in the late 1960s,
while I was interning with the late marine
scientist Dr. Thomas Poulter, a harbor seal
in an indoor lab pool was able to perceive the
difference between two coins the size of a
quarter—one made of aluminum, the other
of steel—using echolocation from 25 yards
Elephants and some large whales (again)
send out very low-frequency vocalizations
to communicate over long distances. When
conditions are right, an elephant’s low-frequency signals can travel through the air
a couple of miles in a forest if unimpeded
by human industrial sound like chainsaws,
generators, drilling and mining equipment, and large logging trucks. With the
elephants’ ground signals, the surface layer
across the terrain vibrates as the signals are
transmitted and received through the large
pads of their feet. Moreover, under optimum conditions, low-frequency elephant
vocalizations could be detected up to 20
miles away (the distance across the widest
part of Long Island)! Meanwhile, some
whales’ low-frequency voices are powerful
enough to circle the globe if not blocked by landmass or human noise pollution in their marine biomes.
Those particular whale voices are so low that we can’t actually hear them. But we can feel the sounds viscerally if we’re
within range and in the water at the same time those signals
are being transmitted.
Still, we humans retain the same hearing equipment that
all other mammals have—the eardrum, the tiny middle ear
bones we call the hammer, anvil, and stirrup, and the net-
work of sensitive hair cells and nerves in the inner ear that
sends those signals to the brain where they are sorted and
given meaning or filtered out as being of little or no value.
With the presence of noise, our brains expend a lot of
energy evaluating many useless signals that, nonetheless,
have an effect on us, whether we want them to or not. Even
equipped with the same general listening tools as other
mammals, our devolution to substandard hearing may be
primarily due to our lopsided reliance on vision to engage
with our surroundings.
Or maybe it’s just disuse. In the wild, acute hearing is
crucial for detecting potential prey and the approach of
predators and other dangers. Not only did we use our hearing
when we hunted, but—here’s the kicker—it served as an
aural GPS to guide us through unfamiliar terrain at night
without the aid of artificial light and where there was no way
to navigate by starlight because of the dense forest canopy
Natural environments aren’t necessarily less complex
than noisy urban habitats, although, if a wild biome is
healthy, it’s likely to be way more acoustically organized into
neat sonic niches, with each critter or species’ voice establishing its own special bandwidth or acoustic turf just like
instrumental voices are organized in a musical composition.
Think of the soundscapes of a particular place as a 24/7
environmental news report. It’s where each habitat produces
its own cohesive biophonic expression, an understandable
narrative portrayed in an ancient protolanguage. Urban
soundscapes, on the other hand, tend to be far more disorganized and incoherent.
Complexity is a key feature of urban anthropophonies.
Walk through any construction zone in New York City, where
wrecking balls are taking down a building, water hoses are wetting down the dust clouds created by the collapsing
walls, and compressors can be found running off roaring
generators. Trucks, meanwhile, jockey in and out of the area
removing debris. All this stuff is hopelessly loud, with lots of
competing and irritating sound sources. But there is no clear
message to be heard within all that racket.
Even if we try, our brains become overwhelmed when
attempting to make sense of the chaos. Natural environments tend to be more organically (naturally) structured—an expressive refrain containing lots of detailed
information, voices that have evolved to stay out of one
another’s acoustic turf. The other is human-generated, utterly random, and assertively driven. One is healthful for
you. The other, no matter how resilient you think you are,
can literally make you ill.
When we hear these unstructured urban soundscapes,
our mind reacts because the signals clash with our brain’s
need for order. Those that we receive contain combinations
that we don’t necessarily comprehend. We may generally
recognize the source, but since the sounds themselves are
not structured for focused messaging, our brains expend
energy trying to filter and make sense of the signal.
Incoherent electromechanical signals are not part of the
natural environments from which we’ve evolved, so we fail.
Consequently, when in the presence of acoustic incoherence
we’re often left feeling tired or stressed in response, with no clear means to alter the effect. No matter how hard your
brain tries to sort out the signals, a steady diet of urban
noise is not easy to manage.
You may not be entirely conscious of the physiological
impact on your system during these eruptions of noise. But it’s likely that your blood pressure and glucocorticoid
enzyme (stress indicator) levels will become measurably
elevated. In this case, it happens when we find ourselves
afflicted by disruptive types of soundscapes. We hear the
noise, but the signals, other than affecting our physical
wellbeing and coming across as annoying, produce no other
obvious outcomes—in the beginning, at least. Other than
affecting our sleep cycles, a garbage truck picking up trash
at 4:30 in the morning means little or nothing to our mammalian brains.
Noise takes up space in the parietal and temporal lobes
of our brain’s processing centers. If its presence is too
overwhelming and prolonged, you may well feel the anxiety
that that noise induces and discover too late that it can
weaken your immune system. These types of sound are not
Just for the fun of it ...
1. Pay careful attention to the ways you communicate within a field of noise.
2. How much energy do you expend ...
- by talking louder?
- by being still trying to make out what another person is communicating?
- by waiting for the noise to dimin- ish or go away altogether?
- by getting exhausted and just abandoning the noise field altogether?
Excerpted from The Power of Tranquility in a Very
Noisy World by Bernie Krause. Copyright © 2020
by Bernie Krause. Reprinted with permission of
Little, Brown and Company. All rights reserved