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With their finely tuned ears, Acoustic biologists have delved into the intricate world of animal communication, discovering that it's a symphony of more than just simple calls like, 'Here I am!' or 'I'm looking for a friend.'
Sound, a universaltool for functioning and socializing, unites us all, from the tiniest insects to the majestic elephants and even humans, especially in dark, underwater, or heavily forested environments.
Laurel Symes, a biologist at Dartmouth College who studies crickets, acknowledges that despite our understanding of the world, there's a cacophony around us full of untapped information. We're only scratching the surface of the world's sound.
Recently, scientists have advanced the field of bioacoustics by recording entire environments rather than just the animals that inhabit them. This approach, known as 'acoustic ecology ', involves listening to the ambient sounds of an ecosystem, such as rain, streams, and wind through the trees. A deciduous forest, for example, sounds different than a pine forest, and the soundscape changes seasonally, providing valuable insights into the dynamics of these ecosystems.
Seth Horowitz, neuroscientist and author of The Universal Sense:How Hearing Shapes the Mind, is particularly interested in how all of these sounds, which are essentially vibrations, have shaped the evolution of the human brain. Sound, as a form of vibration, has played a crucial role in developing the human brain, influencing our cognitive abilities and social interactions.
"Vibration sensitivity is found in even the most primitive life forms," according to Horowitz, including bacteria. "Knowing that something else is moving near you, whether a predator or food, is critical to your environment. There is vibration everywhere you go, and it tells you something."
According to Horowitz,hearing is unique among the senses. Sound can travel a long distance and spread through anything, including the ground and water. It works at night and can go around corners. "Sounds provide sensory input not constrained by your field of vision."
Given how well sound reflects what's happening around us, vertebrate brains, including humans, have evolved to be exquisitely sensitive to it.
"You hear anywhere from 20 to 100 times faster than you see," Horowitz says, "so everything you perceive with your ears colors every other perception and conscious thought you have." For instance, a loved one's voice can evoke strong emotions and memories, influencing thoughts and feelings. "Sound gets in so fast that it modifies all the other input and sets the stage for it," he says.
It can do so because the auditory circuitry in the brain is less widely distributed than the visual system. According to Horowitz, the circuitry for vision "makes the map of the New York subway look simple," whereas sound signals do not have to travel as far in the brain.
The sound is quickly routed to parts of the brain that deal with very basic functions—"precordial areas," according to Horowitz—that are not wired for conscious thinking. These are the places where emotions are born.
"We're emotional creatures," Horowitz says, "and emotions are evolutionary 'fast responses' — things that don't require thought."
That quickness pays dividends in terms of survival: "Do you hear a loud noise?" he asks. Be prepared to flee." Emotions are quick delivery systems in the brain, and sound drives them.
As a result, sound hits you square in the gut. However, the sound is also rich in information-carrying patterns.
Horowitz describes the brain as "a wet, sloppy drum machine." It's desperate for rhythms—not only rhythm but also pitch patterns with mathematical regularity that capture the brain's attention.
For example, a familiar voice's sound has its rhythm and pitches. Natural sounds like birds, insects, and rain also have rhythms and pitches. The Bayaka people of Central Africa's rain forest incorporate the syncopation of falling rain into their music.
In the end, as a human, maybe you need only headphones and peaceful music to be alone.