Stories tagged sound

Jul
07
2008

Ancient wall art at Cave at Lascaux, France: Was music used here to soothe the savage breast?
Ancient wall art at Cave at Lascaux, France: Was music used here to soothe the savage breast?Courtesy Thag the caveman
Do you enjoy hearing your favorite rock group perform their ear-splitting music in a huge cavernous concert arena with flashing colored lights and giant video imagery? Or listening to hymns and spirituals bounce off the vaulted ceiling of a church full of colorful stained-glassed windows and religious icons? Well, I’ve got news for you. It could be you’re attracted to such things by a deep-seated urge to mix echoing music and art; a practice mankind has apparently been doing since the Stone Age. At least according to a new theory coming out of the University of Paris.

Professor Iegor Reznikoff, a specialist in the resonance of building and spaces, theorizes that the most resonant areas of prehistoric-era caves are also the locations where most of the cave wall paintings appear.

Reznikoff stumbled upon the idea by accident.

"The first time I happened to be in a prehistoric cave, I tried the resonance in various parts of the cave, and quickly the question arose: Is there a relation between resonance and locations of the paintings?"

Reznikoff tested his theory inside various well-known French caves where prehistoric art adorned the walls. As he moved about each space, singing and humming, Reznikoff measured where the optimum resonance occurred.

To his surprise, the most resonant areas of each cave were usually spots where most of the cave art was concentrated. And where the resonance was the greatest, the artwork was the densest. In smaller spaces, such as narrow passages between larger cavern rooms where painting would have been difficult, the walls were marked with red lines.

Bear Bone Flute: Neanderthal-aged flute made from bear's femur
Bear Bone Flute: Neanderthal-aged flute made from bear's femurCourtesy Wikipedia
It occurred to Reznikoff that perhaps a cave’s acoustics was important to prehistoric culture, and may be the reason why primitive musical instruments, such as a Neanderthal flute made out of the femur of a bear, have been found in similar caves.

"The [prehistoric] tribes could make sounds with stones, pieces of wood, different types of drums and so on," Reznikoff says. "Of course the Paleolithic tribes did sing, as do all cultural groups from other regions. That they did so in the caves is shown by my studies. The ritual purpose appears very convincing."

This may explain why the popularity of cavernous concert halls, and large arena music performances, or even subterranean music clubs continue to be popular to this day. Perhaps the ancestral effects of long ago cave rituals still resonate in us.

LINKS
Story at ScienceDaily
Listen to the Bear Bone Flute

The cells of our bodies are constantly in motion. In fact, zap them with light and they vibrate, creating sound – much too faint to hear, but sensitive instruments can record the vibrations. Two biologists at the University of Manchester in England have found that healthy cells vibrate differently than cancerous cells. They are hoping to use this to develop new, less-invasive tests to diagnose cancer.

No, it wasn't Thomas Edison. Rather, French inventor Édouard-Léon Scott de Martinville developed a primitive sonogram -- a means of making a picture of sound -- nearly 20 years before Edison's phonograph. Unfortunately, de Martinville had no way of playing the sound back -- a rather serious limitation. Recently, however, scientists at Lawrence Berkeley National Laboratory in California programmed a computer to read the sonogram and reproduce the sound -- a mere 148 years after the picture was made. Edison still gets credit for the first machine to play recorded sound.

Jan
20
2008

A famous dog translator: David spent years speaking with his neighbor's dog, Harvey, without the aid of Hungarian computers. Fortunately, we can't all be like him.
A famous dog translator: David spent years speaking with his neighbor's dog, Harvey, without the aid of Hungarian computers. Fortunately, we can't all be like him.Courtesy Wikimedia commons
“Doctor, no! I need those!” “Kibbles and bits, kibbles and bits,” “It tasted great both times I ate it,” and “Rook out, Raggy!” All exclamations humanity has every right to expect from a dog. The canine linguistics community, however, has been left sorely disappointed by the recent bark translations of a team of Hungarian researchers.

The Hungarians, no doubt doing their best with the resources at hand, recorded and digitized over 6,000 barks of Hungarian sheepdogs, and fed them into a specially designed computer program. The computer was then able to correctly identify, 43 percent of the time, whether the dog was barking in a “fight,” “stranger,” “play,” “walk,” “alone,” or “ball” scenario, with “fight” and “stranger” most often yielding accurate results. The program was also able to correctly determine the individual dog barking 52 percent of the time.

Both of these statistics are much better than the average human translation of dog barking, although they pale in comparison to some of history’s more notable dog translators (Shaggy, The Son of Sam and Jack London, to name just a few). It is, certainly, an admirable start, and it has got me looking forward to the day when I can ask my brother’s dog just what’s so great about putting his nose right there, exactly.

May
18
2007

Can you hear me know?: Biologists are using recorded whale songs played through underwater speakers to lure a pair of wayward humpback whales out of the Sacramento River in California. (Photo from the U.S. National Oceanic and Atmospheric Administration)
Can you hear me know?: Biologists are using recorded whale songs played through underwater speakers to lure a pair of wayward humpback whales out of the Sacramento River in California. (Photo from the U.S. National Oceanic and Atmospheric Administration)
Last winter it was a direction-less whale found up the Thames River near London. Now it’s two injured humpbacks found up the Sacramento River in California, 90 miles away from their normal ocean surroundings.

Ocean biologists are hopping to use recordings of humpback whale songs to lure the two wayward whales back to the ocean. Not only do the animals need to be moved for their own safety and comfort, but their presence has also tied up boat traffic on the river as well.

The plan was to use underwater speakers connected to a boat to play the whale songs to attract the whales down the river as the tide goes out. A flotilla of boats would be behind the whales, cutting off any escape routs back upstream.

Whale river: The mother whale slaps her tail in the Sacramento River. (Photo from USA Today)
Whale river: The mother whale slaps her tail in the Sacramento River. (Photo from USA Today)
The whales were first spotted in the river on May 13. They very likely were on their northward migration from their wintering waters off of Mexico. And some photos of the whales show they’ve been injured, probably by a boat propeller, but if they can get to the cleaner waters of the sea, the injuries have a good chance of healing without treatments.

Apr
18
2007

The amphitheater at Epidaurus has acoustics so good you can hear a pin drop, even when the seats are packed with 15,000 people: Photo by Randy Peters from flickr.com
The amphitheater at Epidaurus has acoustics so good you can hear a pin drop, even when the seats are packed with 15,000 people: Photo by Randy Peters from flickr.com

The ancient Greek amphitheater at Epidaurus has long been famous for its marvelous sound qualities. Audience members in the back row could hear every sound, even as soft as a match being struck.

Until recently, no one has unlocked the secrets of these perfect acoustics. The Greeks themselves thought it was the shape of the amphitheater. But other theaters built on the same model could not reproduce the sound quality of Epidaurus.

Now, researchers at the Georgia Institute of Technology have finally solved the problem. They found that the limestone seats work as a filter to dampen the sound of the crowd, while at the same time amplifying the sounds from the stage, . Other amphitheaters used the same design but different materials, and were never able to duplicate the results.

Mar
20
2007

Vibrations create cool patterns

Vibrating surfaces create sound waves. In the video below a plate of metal is vibrated with higher and higher frequencies. Salt spinkled on top of the plate can only stay where the surface is not vibrating. The nonvibrating areas are called nodes. Distance between nodes is shorter for higher frequencies.Standing waves
Standing waves
The patterns you see are known as standing waves. We have an apparatus like this at the Science Museum of Minnesota on the third floor. You might also try to make standing waves in a stretched slinky.

Try doing this yourself

I once stretched rubber from a large balloon over the front of a large car speaker. Using an amplifier and frequency generator, I was able to make similar patterns in salt sprinkled on top of the sheet of rubber. You could try an electric keyboard to produce the different frequencies of sound.

Want to see a longer video?

If you have time here is a link to part 1 of some extraordinary film clips of Hans Jenny experiments from the 1960's and early 70's(28 minutes).

Mar
18
2007

Stradavarius sound from graphite and balsa

Violin engineering: image modified from TheViolinSite.com via wikipedia
Violin engineering: image modified from TheViolinSite.com via wikipedia
Can we make violins today that sound as sweet as those made by Antonio Stradivari? Joseph Curtin (Ann Arbor, Mich.),who received a 2005 MacArthur Foundation “genius award” for his violin designs, thinks so. In reference to violins made by Douglas Martin, Curtin stated that

“the traditional violin became obsolete in early July of 2005.”

One of Mr. Martin's prototype violins, Balsa 4, when passed around at a violin design workshop at Oberlin College, startled the participants with its punch and responsiveness. Using balsa for lightness and graphite for stiffness, Martin is breaking the traditional violin design rules.

New materials "sing"

Another violin maker to use modern materials like graphite fibers is Martin Schleske. Ingolf Turban, a touring concert violinist, compared Mr. Schleske’s latest violin, which has a top made of a mix of spruce and graphite, with a 1721 Stradivarius by recording passages from Mozart’s Violin Concerto in D Major with each. He told Mr. Schleske he preferred the new one.

I have never been playing any violin with such a singing E string,” Mr. Turban said in a testimonial. “It is no longer like playing violin but like singing.”

Violin acoustics analysed in physics laboratory

George Bissinger, a physicist at East Carolina University in Greenville, N.C., is using medical-imaging gear, laser scanners, arrays of microphones and computers to measure and model how the parts of a violin react once energy is introduced by a bow, fingertip, pick or, in the laboratory, the repeated taps of a tiny hammer.

Particularly important, Dr. Bissinger said, is determining which factors translate the side-to-side sawing of a bow on a string into vertical motions of the violin top. “Up and down is what matters,” he said.
Another important influence, particularly on low violin notes, is the movement of air in and out of the f-holes, Dr. Bissinger said. If the dimensions are right, the air sloshes forward and back like disturbed water in a bathtub (or air in an organ’s pipes) at rates that increase the instrument’s volume.

Want to learn more?

I recommend viewing the video and multimedia graphics found in the New York Times post, "String Theory: New Approaches to Instrument Design".