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Science News
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Researchers in the US have been studying tipsy fruit flies to try and understand what happens to our genes when we go out on the beers. Humans and fruit flies respond t... |
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Scientists have discovered a population of bacteria thriving 2.8 kilometres underground, which rely on radiation produced by uranium for survival. The findings make the ... |
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If you're like me, and have a terrible memory, then at last we may have an excuse and can blame it on our genes. Scientists in the US have identified a gene responsible ... |
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US Researchers have developed a test which can detect the spread of melanoma, a form of skin cancer, by listening out for the presence of cancerous cells in the blood. ... |
Kitchen Science
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Investigate what is happening when you get dizzy in some perculiar directions, with nothing but an office chair, and some soft grass.
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Questions

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The Earth's core is basically molten and the Earth is in the region of four billion or so years old. How come it hasn't cooled down over the last four and a half billion years, and why hasn't man tried to tap into all that energy?
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We have tried to tap into that energy. Iceland is one of the biggest banana producers in the world, and the reason is that they use this geothermal energy. Iceland has a lot of hot magma near the surface, and so they use that heat to do all sorts of things. There are other places around the world where they use this heat in the hot Earth around them to heat water and power things. But the ultimate question of where does that heat come from, is that the heat has, to a certain extent, always been there. The Earth is a huge body, and as a result, it has a huge amount of energy trapped under its surface, but it has cooled down. When the Earth was first formed, it was essentially a blob of molten material in space. Since that time it has cooled a lot, but because we're quite a big planet, we haven't lost all our heat yet. Then there's a second contribution. In the early days of the Earth when it was still molten, all the heavy and dense elements sunk deeper into the Earth's crust than the lighter ones. The heavy dense things were the ones that might be radioactive and for a while, people were suggesting that there might be a big geo-reactor under the Earth. This is a giant natural nuclear reactor and when you get critical masses of the right materials in the right place at the right time, they can begin their own chain reaction. That produces heat and we think that that might be contributing to heating the Earth up.
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If all these bats are whizzing about and making all these noises, how do they not fly into each other? How do they know who's noise is who's?
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They're all tuned to different frequencies, but only very slightly different frequencies. Some of them will be tuned to 61.45 kHz, others will be tuned to 61.44 kHz and so forth. Because their ears are so narrowly tuned, they can pick up these very narrow echoes that come back. So they're very specifically only hearing their own noises coming back.
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If bats can do this, why aren't aeroplanes equipped with the same sort of things?
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Aeroplanes are, but just not at those frequencies. They use other types of techniques such as radio waves for finding direction, landing and other components. Bats are not equipped with radio receivers, but they are equipped with sound receivers and they use those instead. Submarines use sonar, which is the same sort of thing. They borrowed that from bats and dolphins.
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I have very sensitive hearing and I don't like sudden loud noises or repetitive sounds. I am also very sensitive to sun light and bright lights. I was wondering if there's any medical condition or are the two related in any way?
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Some people have more sensitive hearing than others and it's called hyperacusis. I'm very interested in that but I don't know the basis for it. I don't know whether it's a central basis or a peripheral basis. It would be fairly straight forward to check that out. I guess the other interesting question is whether people sensitive to some types of sound are more likely to find visual stimuli aversive as well.
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Is it true that sound travels further in cold weather than in warm weather and how does this work?
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The speed of sound does depend on temperature and it is slower at colder temperatures, so it can sound different. Deep down, sound is the vibration of molecules and if you've got a lower temperature and you meet them, they just vibrate a bit slower.
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Why is it that when you're in a car and going past a bunch of other parked cars all in a long row, you hear a swoosh for every other car you go past? Is it the gap in between the car filled with air that interacts with the turbulence made by the moving car that makes you hear this?
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My best guess would be that it's quite a good guess! I have no idea. It would be some sort of turbulence effect. We're used to turbulence making noise, which is how things like recorders work. But you also get that whooshing sound from cars when you go past, or if you stand on a platform and a high speed train is going past.
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| Interviews
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Chelsea Wald and Bob Hirshon from AAAS, the science society
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Dr Bob Carlyon, MRC Cognition and Brain Sciences Unit
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Professor Ian Russell, University of Sussex
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Professor Albert Feng, University of Illinois
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Professor Trevor Cox, University of Salford
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Fact or Fiction
One in ten of the world's active volcanoes are in
Japan
 
It's True - Japan is quite literally a hotbed of
seismic activity. It has over 75 active volcanoes, and
one in five of all major earthquakes (mesuring over 6
on the Richter Scale) occur in Japan.
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When we take a deep breath there are more molecules
of gas in our lungs that there are stars in the universe
 
It's True - Just a couple of litres of air that you breathe
in contains more molecules of nitrogen and oxygen than
we think there are stars in the known universe. There
are a gob-smacking 50 million million molecules (50 x
10^12) molecules in the lungs of every person on Earth.
And when you breathe them out they all get mixed up in
the air around you. So each of us, every time we breathe,
is taking in a few molecules that have been breathed previously
by everyone, and everything, that's ever lived!
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Human hairs are about half a millimetre in diameter
 
It's False - Not quite - Human hairs measure between
40 and 120 microns (thousandth's of a millimetre) across,
meaning that the thickest hairs are about one tenth of
a millimetre in diameter.
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The average oxygen molecule in the air around you
in travelling at over 1000 miles per hour
 
It's True -
The average oxygen molecule is zipping past you at 416
metres per second or 1000 miles per hour and the hotter
it gets the faster it goes. But the molecules don't get
tot travel very far because the almost immediately smash
into something. In fact, they're smashing into at least
3 and a half billion other atoms every single second!
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Australia's amazing mammal the Duck-Billed Platypus
actually lays eggs
 
It's True - The platypus is a monotreme
and together with its spiny relative, the Echidna, it
lays eggs.
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Tea bags were invented in the 1850's
 
It's False -
Tea Bags date from 1908 and, according to legend, were
the brain child of a certain Thomas Sullivan, from New
York. Teapots, on the other hand, were invented in China
during the Ming dynasty (1368-1644).
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| How We Hear, Echolocation and Giant Whoopee Cushions - More about this podcastOn this week's edition of the Naked Scientists radio show and podcast, Bob Carlyon from the MRC Cognition and Brain Sciences Unit, Ian Russell from Sussex University and Trevor Cox from the University of Salford will be trying to tune us in to the science of sound, as Sabina Michnowicz explains...

| Figure 1: Head of the moustached bat. From drawings in Silva-Taboada, G. 1979. Los murciélagos de Cuba. La Habana: Editorial Academia | This week on the Naked Scientists we bring you naked sound - cutting edge research will be making its way from the frontlines of science via the radio straight to your ear. Professor Ian Russell will discuss his research with the greater moustached bat, Professor Trevor Cox will explain the importance of architectural sound and Dr Bob Carlyon will tell us about cochlear implants. There are three acoustic experts in the mix and their combined sound will educate, enlighten and entertain!
Ian Russell is a fellow of the Royal Society and each year swaps his lab at the University of Sussex for a spell of research in a hot cave in Cuba, (over 40 degrees C and 100% humidity). Why does he choose this summer destination? Because that's where the Greater Moustached Bat 'hangs' out! But this is no ordinary bat - it has the most finely tuned hearing system of any animal in the world (check out its mug shot in figure 1). Ian has been observing these animals in order to find out how they've evolved to navigate perfectly through pitch black forests at speeds of up to 40mph. By understanding how these bats use sound for navigation, ideas can be explored which may lead to greater knowledge of how humans and other mammals process speech.
Understanding the biological basis of hearing and deafness involves getting to grips with how the inner ear (or "cochlea") works. The cochlea is a tube of bone spiralling round the auditory nerve and is notoriously inaccessible. Ian's work combines mathematical modelling, biophysics, physiology, cell biology and genetics to show how the cochlear cells respond to noise, and this response is translated into electrical signals which the brain processes as sound. As the Greater Moustached Bat is so specialised at hearing, it serves as the perfect model for learning about how the brains of mammals process the sounds they hear, especially how the cochlea amplifies sound by more than a thousand fold.
The cochlea translates sound waves into electrical signals which are interpreted as sound by the brain, but it is also important in providing humans with a sense of balance. Environmental and genetic factors (as well as ageing) can all lead to cochlea damage and result in an irreparable loss of hearing. Genetic disorders are responsible for deafness in 1 in every 1,000 births, whereas over 25% of the population above the age of 75 has significant hearing loss. Research which allows scientists to understand how the cochlea functions are useful to society because they may eventually help to cure deafness and are helpful in improving the quality of hearing aids.
Regarding hearing aids; Bob Carlyon works with cochlear implants and explains hearing and deafness using the House of Commons as a metaphor. Here in his own words is Bob's description of how we filter sound to hear what we need -
"Imagine you are Tony Blair, during Prime Minister's Questions. The Leader of the Opposition is asking a question, but all around you are loud cheers from the Tory benches, and even louder jeers from your parliamentary colleagues. Somehow, your ears and your brain must, together, extract David Cameron's voice from the competing babble. Some of these competing voices will be quite similar to his, some will be louder than his, and the sound will be bouncing around the Chamber and reaching your ears from all directions. Even with one ear, or when listening to the programme on a mono radio, normal-hearing listeners can perform this task remarkably well. To do this, the auditory system exploits physical regularities in sound - such as the fact that, at any given time, different talkers are producing sounds that differ in pitch.
Now, imagine you are deaf. Some deaf people are suitable for a device known as a cochlear implant. Sound is picked up by a microphone worn behind the ear, and transmitted across the skin to a receiver inside the head. The receiver then stimulates the auditory nerve using an array of electrodes, which bypass the damaged receptor cells in the inner ear. Now you can hear again, and many implant users converse very confidently in a one-on-one situation, and even use the telephone. However, you will have great difficulty in noisy situations, such as the one Tony finds himself in on Wednesday lunchtimes."
Bob's research group in Cambridge looks at ways of improving the way that implants encode sound. This will hopefully improve the hearing of implant users in a wide range of situations, including places with lots of background or competing noise, which brings me on to the work of our final expert.

| Figure 2: Trevor Cox on a giant whoopee cushion |
Trevor Cox works with indoor acoustics and his latest research could make hearing easier. For the first time a technique has been developed which accurately measures exactly how sound behaves in "real world" situations, which could help to improve acoustics in all sorts of buildings from concert halls to railway stations. The impact of this technique was first explained at the British Association Festival of Science in Norwich last month (regular fans will know the Naked Scientists were there also - as ever, treading carefully along science's cutting edge to bring you the latest developments). The technique is designed to pinpoint precisely how indoor environments respond to music and speech while those environments are in everyday use. This opens up the prospect of basing acoustic design on more realistic information about the way sound behaves than has previously been possible. It may also contribute to the development of hearing aids that adapt the way they process sound according to the acoustic environment they are in, thus providing a much better listening experience for hearing aid users. This will be very valuable to the hard of hearing as it's not just the House of Commons that gets very noisy. Up until now the way of measuring acoustics has been to make a short blast of noise (e.g. a gunshot), record it and analyse how it dies away. The noise has to be very loud so that the environment's effect on it can be assessed across the full range of sound, from very loud to very quiet - only in this way can comprehensive information on an environment's acoustic performance be obtained. However, gunshot noise poses a risk to hearing and is unpleasant to listen to. This means that measurements taken in unoccupied areas are the norm even though these do not accurately indicate 'real' acoustic performance when people are present, moving and talking etc. Now, with EPSRC (Engineering and Physical Sciences Research Council) funding, Trevor is leading a team of engineers at the University of Salford in a project to explore whether the loud, short blast of noise could be replaced by music played at an average level of audibility, or even the conversation of people in the indoor environment being tested.The team are developing groundbreaking computer programmes capable of isolating snippets or phrases from normal music or speech, analysing their decay and extrapolating this data so it provides an accurate indication of an environment's effect on sound. Since loud test sounds are not required, this approach avoids the need to vacate the environment when testing takes place, enabling more realistic acoustic data to be gathered. Last week Trevor also delivered 'Beautiful Music, Horrible Sounds' to an audience of 7-14 year olds by exploring what sound is, why different sounds provoke positive and negative reactions, and how technology can be used to make sounds nicer - or nastier. It also explained why humans have two ears. Volunteers sat on a specially made 2 metre-diameter whoopee cushions - the largest in the world (Figure 2) - to demonstrate exactly how wind instruments work. The physics involved when whoopee cushions make a noise is the same as blowing through the mouthpiece of a saxophone, for instance (although the sound produced is quite different!)
So, to hear more about the naked sound of science turn on and tune in!
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