acoustics Tagged ‘acoustics’

Dolphins And Math Skills

Thursday, July 19th, 2012

 

Dolphins May Be Math Geniuses

The brainy marine mammals could be far more skilled at math than was ever thought possible before.

By Jennifer Viegas
Tue Jul 17, 2012
THE GIST

  • Complex, nonlinear math appears to explain a primary dolphin hunting technique.
  • The math involves addition, subtraction, multiplication and ratio comparisons.
  • It is possible that dolphins possess remarkable inborn math skills.
bottlenose dolphins

Bottlenose dolphins swimming. Analysis of a dolphin hunting technique suggests the animals may be natural math geniuses.
Corbis

Dolphins may use complex nonlinear mathematics when hunting, according to a new study that suggests these brainy marine mammals could be far more skilled at math than was ever thought possible before.

Inspiration for the new study, published in the latest Proceedings of the Royal Society A, came after lead author Tim Leighton watched an episode of the Discovery Channel’s “Blue Planet” series and saw dolphins blowing multiple tiny bubbles around prey as they hunted.

“I immediately got hooked, because I knew that no man-made sonar would be able to operate in such bubble water,” explained Leighton, a professor of ultrasonics and underwater acoustics at the University of Southampton, where he is also an associate dean.

“These dolphins were either ‘blinding’ their most spectacular sensory apparatus when hunting — which would be odd, though they still have sight to reply on — or they have a sonar that can do what human sonar cannot…Perhaps they have something amazing,” he added.

Leighton and colleagues Paul White and student Gim Hwa Chua set out to determine what the amazing ability might be. They started by modeling the types of echolocation pulses that dolphins emit. The researchers processed them using nonlinear mathematics instead of the standard way of processing sonar returns. The technique worked, and could explain how dolphins achieve hunting success with bubbles.

The math involved is complex. Essentially it relies upon sending out pulses that vary in amplitude. The first may have a value of 1 while the second is 1/3 that amplitude.

“So, provided the dolphin remembers what the ratios of the two pulses were, and can multiply the second echo by that and add the echoes together, it can make the fish ‘visible’ to its sonar,” Leighton told Discovery News. “This is detection enhancement.”

But that’s not all. There must be a second stage to the hunt.

NEWS: Dolphins, Humans Share ‘Brainy’ Genes

“Bubbles cause false alarms because they scatter strongly and a dolphin cannot afford to waste its energy chasing false alarms while the real fish escape,” Leighton explained.

The second stage then involves subtracting the echoes from one another, ensuring the echo of the second pulse is first multiplied by three. The process, in short, therefore first entails making the fish visible to sonar by addition. The fish is then made invisible by subtraction to confirm it is a true target.

In order to confirm that dolphins use such nonlinear mathematical processing, some questions must still be answered. For example, for this technique to work, dolphins would have to use a frequency when they enter bubbly water that is sufficiently low, permitting them to hear frequencies that are twice as high in pitch.

“Until measurements are taken of wild dolphin sonar as they hunt in bubbly water, these questions will remain unanswered,” Leighton said. “What we have shown is that it is not impossible to distinguish targets in bubbly water using the same sort of pulses that dolphins use.”

If replicated, the sonar model may prove to be a huge benefit to humans. It might be able to detect covert circuitry, such as bugging devices hidden in walls, stones or foliage. It could also dramatically improve detection of sea mines.

“Currently, the navy uses dolphins or divers feeling with their hands in such difficult conditions as near shore bubbly water, for example in the Gulf,” he said.

How Stuff Works: Dolphins

In terms of dolphin math skills, prior studies conducted by the Dolphin Research Cetner in Florida have already determined that dolphins grasp various numerical concepts, such as recognizing and representing numerical values on an ordinal scale. Marine biologist Laela Sayigh of the Woods Hole Oceanographic Institution said, “In the wild, it would be very useful (for dolphins) to keep track of which areas were richer food sources.”

While dolphins are among the animal kingdom’s most intelligent animals, they are not likely the only math champs.

Parrots, chimpanzees and even pigeons have been shown to have an advanced understanding of numerical concepts. The studies together indicate that math ability is inborn in many species, with number sense, mathematical skills and verbal ability perhaps being separate talents in humans that we later learn to combine.

 

from:    http://news.discovery.com/animals/dolphins-math-geniuses-120717.html

New Theory About Stonehenge

Monday, June 25th, 2012

Stonehenge a Monument to Unity, New Theory Suggests

Stephanie Pappas, LiveScience Senior Writer
Date: 22 June 2012
Stonehenge in Great Britain.
The reason for Stonehenge’s construction is unknown.
CREDIT: Albo, Shutterstock

The mysterious structure of Stonehenge may have been built as a symbol of peace and unity, according to a new theory by British researchers.

During the monument’s construction around 3000 B.C. to 2500 B.C., Britain’s Neolithic people were becoming increasingly unified, said study leader Mike Parker Pearson of the University of Sheffield.

“There was a growing islandwide culture — the same styles of houses, pottery and other material forms were used from Orkney to the south coast,” Parker Pearson said in a statement, referring to the Orkney Islands of northern Scotland. “This was very different to the regionalism of previous centuries.”

By definition, Stonehenge would have required cooperation, Parker Pearson added.

“Stonehenge itself was a massive undertaking, requiring the labor of thousands to move stones from as far away as west Wales, shaping them and erecting them. Just the work itself, requiring everything literally to pull together, would have been an act of unification,” he said.

The new theory, detailed in a new book by Parker Pearson, “Stonehenge: Exploring the Greatest Stone Age Mystery” (Simon & Schuster, 2012), is one of many hypotheses about the mysterious monument. Theories range from completely far-fetched (space aliens or the wizard Merlin built it!) to far more evidence-based (the monument may have been an astronomical calendar, a burial site, or both).

The Culture of Stonehenge

Along with fellow researchers on the Stonehenge riverside Project, Parker Pearson worked to put Stonehenge in context, studying not just the monument but also the culture that created it.

What they found was evidence of a civilization transitioning from regionalism to a more integrated culture. Nevertheless, Britain’s Stone Age people were isolated from the rest of Europe and didn’t interact with anyone across the English Channel, Parker Pearson said.

“Stonehenge appears to have been the last gasp of this Stone Age culture, which was isolated from Europe and from the new technologies of metal tools and the wheel,” Parker Pearson said.

Stonehenge’s site may have been chosen because it was already significant to Stone-Age Britons, the researchers suggest. The natural land undulations at the site seem to form a line between the place where the sun rises on the summer solstice and where it sets in midwinter, they found. Neolithic people may have seen this as more than a coincidence, Parker Pearson said.

“This might explain why there are eight monuments in the Stonehenge area with solstitial alignments, a number unmatched anywhere else,” he said. “Perhaps they saw this place as the center of the world.”

Theories and mystery

These days, Stonehenge is nothing if not the center of speculation and mystery. The monument has inspired its fair share of myths, including that the wizard Merlin transported the stones from Ireland and that UFOs use the circle as a landing site.

Archaeologists have built some theories on firmer ground. Stonehenge’s astronomical alignments suggest that it may have been a place for sun worship, or an ancient calendar. A nearby ancient settlement, Durrington Walls, shows evidence of more pork consumption during the midwinter, suggesting that perhaps ancient people made pilgrimages to Stonehenge for the winter solstice, Parker Pearson and his colleagues have found.

Stonehenge may have also been a burial ground, or a place of healing. Tombs and burials surround the site, and some skeletons found nearby hail from distant lands. For example, archaeologists reported in 2010 that they’d found the skeleton of a teenage boy wearing an amber necklace near Stonehenge. The boy died around 1550 B.C. An analysis of his teeth suggest he came from the Mediterranean. It’s possible that ill or wounded people traveled to Stonehenge in search of healing, some archaeologists believe.

Other researchers have focused on the sounds of Stonehenge. The place seems to have “lecture-hall” acoustics, according to research released in May. One archaeologist even suggests that the setup of the stones was inspired by an acoustical effect in which two sounds from different sources seem to cancel each other out.

from:    http://www.livescience.com/21125-stonehenge-theory-unity.html

Acoustics at Stonehenge

Wednesday, May 2nd, 2012

The Stones Speak: Stonehenge Had Lecture Hall Acoustics

Wynne Parry, LiveScience Senior Writer
Date: 02 May 2012
No one knows why ancient people built Stonehenge.
No one knows why ancient people built Stonehenge.
CREDIT: Pete Strasser | nasa.gov

The stone slabs of England’s Stonehenge may have been more than just a spectacular sight to the ancient people who built the structure; they likely created an acoustic environment unlike anything they normally experienced, new research hints.

“As they walk inside they would have perceived the sound environment around them had changed in some way,”said researcher Bruno Fazenda, a professor at the University of Salford in the United Kingdom. “They would have been stricken by it, they would say, ‘This is different.’”

These Neolithic people might have felt as modern people do upon entering a cathedral, Fazenda told LiveScience.

Fazenda and colleagues have been studying the roughly 5,000-year-old-structure’sacoustic properties. Their work at the Stonehenge site in Wiltshire, England, and at a concrete replica built as a memorial to soldiers in World War I in Maryhill, Wash., indicates Stonehenge had the sort of acoustics desirable in a lecture hall

Stonehenge itself is no longer complete, so Fazenda and colleagues used the replica in Maryhill as a stand-in for the original structure. At both locations, they generated sounds and recorded them from different positions to see how the structure influenced the behavior of the sound.

At the replica, they found a reverberation time of just less than one second, the amount of time optimal for a lecture hall. Unlike an echo, which is a single response created when sound waves reflect off something, reverberation occurs when a sound is sustained by a quick succession of reflections arriving at different times.

Modern cathedrals can have reverberation times of about 10 seconds or more, while concert halls are designed so reverberation in them will last between two and five seconds, Fazenda said.

About one second of reverberation is “just enough for us to start becoming aware of it,” he said.

Based on their work at Maryhill, the researchers believe the many stones within Stonehenge would have diffracted and diffused sound waves, creating reverberation. The large amount of diffusion and diffraction would have also lead to good sound quality regardless of where the listener was standing in relation the source of sound within the structure.

“What we found in Maryhill as a model for Stonehenge was you could almost stand behind a stone and keep talking with a good level of voice, and people would be able to hear you somewhere else,” he said.

For the Neolithic people who built this structure, this sort of acoustic environment was likely quite unusual. They appear to have lived in smaller, thatched-roof homes made of wood, which would not have reflected sound as effectively. And the region around Stonehenge has no significant geographical features, like high cliffs, which are associated with echoes, or large caves, which are associated with reverberation, Fazenda said.

While some have suggested that Stonehenge was designed to create certain acoustic effects, Fazenda said he sees no evidence for this.

Rather than search for an acoustic motivation behind the construction of this mysterious structure, this research is intended to help better understand how the ancient people might have used the structure, he said.

Fazenda collaborated with Rupert Till of the University of Huddersfield in the UK and with archaeologist Simon Wyatt on this project.

from:   http://www.livescience.com/20044-stonehenge-acoustics.html