Sound bytes: Using sound technologies to improve the world
Every so often, when the world is at its most depressing, we need a reminder that people are doing their best to improve the world. Perhaps this will give you reason for good cheer today: Scientific explorations are underway that may lead to innovative improvements in healthcare, disaster prediction, and the protection of endangered ecosystems—all of which rely on research involving sound.
Most of these recent projects are still in a research phase and aren't anywhere close to production. But the potential effects make them even more engaging. Oh, the possibilities!
These examples are all upbeat; I intentionally left out downers or "advances" of debatable value. After all, while I may want to chase away teenagers, I'm not sure this is what I had in mind. And if you can get through this entire article without singing along with Kate Bush, you're a stronger person than I am.
A robot bat that uses sound for navigation and mapping
In a scientific experiment that begs for its own comic book, a fully autonomous bat-like terrestrial robot, named Robat, uses echolocation to navigate its environment. Robat can map a physical space solely based on sound, according to a study by Tel Aviv University's Itamar Eliakim and colleagues, published in PLOS Computational Biology.
Like a bat, Robat emits sound and analyzes the returning echoes. It uses an ultrasonic speaker that produces frequency-modulated chirps at a rate similar to that of bats, as well as two ultrasonic microphones that mimic ears. With only sound as its input, Robat can move autonomously and map an area in real time—identifying object borders, classifying them using an artificial neural network, and avoiding obstacles.
"To our best knowledge, our Robat is the first fully autonomous bat-like biologically plausible robot that moves through a novel environment while mapping it solely based on echo information—delineating the borders of objects and the free paths between them and recognizing their type," according to the scientists.
A way to detect tsunamis earlier using underwater sound waves
Scientists at Cardiff University have developed a new method to calculate a tsunami's size and destructive force by evaluating high-speed acoustic gravity waves (AGWs). Doing so helps them know what to expect well in advance of the tsunami making landfall, which suggests the possibility of better real-time early-warning systems.
The sound waves are naturally occurring, generated in the deep ocean after tsunami trigger events, such as underwater earthquakes, the university explains. The AGWs may travel over 10 times faster than tsunamis and spread out in all directions. That makes them easy to pick up using standard underwater hydrophones, as the Cardiff University scientists demonstrated. "Our aim is to be able to set off a tsunami alarm within a few minutes from recording the sound signals in a hydrophone station," notes the lead author of the study, Usama Kadri.
A 'brain stethoscope' that listens for silent seizures
A computer music specialist has helped Stanford neurologists develop a "brain stethoscope." By converting brain waves into sound, even non-specialists can detect a certain kind of epileptic seizure.
According to the university researchers, medical students and nurses—non-specialists, in other words—"can listen to the brain stethoscope and reliably detect so-called silent seizures." In such neurological conditions, patients have epileptic seizures without any of the associated physical convulsions.
Instead of putting a device against a patient's chest, an algorithm translates the brain's electrical activity into sounds. The brain stethoscope can help technicians assess a patient and determine if the patient is having a silent seizure, according to Josef Parvizi, professor of neurology and neurological sciences at Stanford.
Acoustic sensors that measure biodiversity
The environment is in trouble. Humanity has caused the loss of plants, animals, and microbes at unprecedented rates. As just one example, nearly 40 percent of the major vertebrate groups (e.g., amphibians, mammals) are in a threatened or endangered status; current extinction rates are close to those following the die-off of the dinosaurs.
To create a better future for all 11 million species (including the human one), Purdue University's Center for Global Soundscapes is conducting a project to explore how humans impact biodiversity. To do so, the scientists are using acoustic sensors, artificial intelligence tools, and big data mining techniques.
Using more than 4 million audio recordings from around the world, the scientists are studying biodiversity trends in the face of climate change and habitat alteration. Recordings contain a mix of complex sounds, collectively called a soundscape, including the acoustic signatures of the geophysical environment and sounds made by humans. These acoustic signals provide metrics to gauge climate dynamics and human activity patterns, such as energy use.
For example, when Purdue professor Bryan Pijanowski listens to nighttime recordings in forests, "I can hear gaps—I can hear animals that should be there and aren't there. They're not participating in the chorusing at night, for example." To identify issues and perhaps find solutions, his project has collected a petabyte of data: 4 million files from more than 600 places around the world. "I'm trying to study every major biome of the world. I have all of them done except three," he says, though he's working on those last three.
Among the projects underway: assessing coral reef recovery from hurricanes using continuous audio recordings in Puerto Rico; measuring the impacts of livestock overgrazing in the steppe ecosystems of Mongolia; and determining how coffee plantation management strategies affect biodiversity.
Ultimately, this connects to world hunger. Pijanowski is defining a space that people would want to live in, says fellow Purdue professor Richard Grant. The sound project merges into "the sustainability of those kinds of environments while feeding the world," he says.
Sound with a vision: Purdue University Soundscapes records a planet
Bryan Pijanowski, Purdue professor of landscape and soundscape ecology and director of the Discovery Park Center for Global Soundscapes, is on a mission to record the earth.
A laser device that whispers secret sounds into your ears
In a lab test, the MIT researchers used a laser to transmit an audible message at a conversational volume, without any type of receiver equipment. "Our system can be used from some distance away to beam information directly to someone's ear," research team leader Charles M. Wynn told the Optical Society. "It is the first system that uses lasers that are fully safe for the eyes and skin to localize an audible signal to a particular person in any setting." The researchers plan to demonstrate the methods outdoors at longer ranges.
The point is to send messages to individuals in a crowd without blasting them over loudspeakers. Among the possible uses for this technology: to communicate across noisy rooms, warn security staff of dangerous situations, or enable instant language translation for conference attendees.
A personal sound bubble that replaces headphones
Science fiction is peppered with the desire for controlled spaces, from the "privacy mode" depicted in the "Babylon 5" pilot episode to the "Get Smart" cone of silence. Now, it appears, scientists are working on actual virtual sound bubbles that could replace headphones.
Taewoong Lee of Aalborg University created isolated "bubbles" of sound that permit multiple people to listen to different sound tracks in the same room without disturbing one other. The scientific advance, which earned him the North Jutland University Foundation's Innovation Prize, is currently in the process of being patented. You can watch a demonstration here.
Where can it go? Sound zones could permit children to watch movies in the back seat of a car while parents listen to the radio in the front. Or it could be used at concerts and festivals to avoid disturbing neighbors.
Hearing the future
Whether we listen to ambient noise or focus the frequencies beyond the range of human hearing, sound waves can change how the world works. And isn't that a happy thing to contemplate?
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