Going Topless Harms your Hearing

11 January 2011
Presented by Chris Smith, Kat Arney.

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In this week's NewsFlash, we find out how an IVF study could lead to a test to predict the treatment's outcome, how a woman's tears can manipulate men's moods, the perfect melody to send shivers up your spine and the headphones which can cancel out the sound of the dentist's drill. Plus we find out how leaving the top down on your car could damage your hearing....

In this episode

00:26 - IVF study could lead to prediction test

More than 10 per cent of couples worldwide are infertile, and some of them turn to in vitro fertilisation or IVF, in the hope of having a baby. But it can be a difficult and heartbreaking process for many couples and there's no guarantee of success. But now a new study could lead to a more accurate test to predict how likely a couple are to succeed with the procedure.

IVF study could lead to prediction test

More than 10 per cent of couples worldwide are infertile, and some of them turn to in vitro fertilisation or IVF, in the hope of having a baby. But it can be a difficult and heartbreaking process for many couples and there's no guarantee of success, although thousands of IVF babies are born healthy and happy every year.

But now a new study from researchers based in Glasgow and Bristol, published in the journal PloS Medicine, could lead to a more accurate test to predict how likely a couple are to succeed with the procedure.

A heavily pregnant woman.The researchers, Scott Nelson and Debbie Lawlor, looked at the outcomes of every single IVF cycle in the UK between 2003 and 2007 - a staggering total of more than 144,000 cycles. Then they looked at a range of factors, including the age of the mother, how long the couple had been infertile for, previous IVF attempts, whether the mother's own eggs or donor eggs were used, and the particular techniques used, then correlated that with whether the IVF was successful, and whether there were any problems with the babies, such as  being born prematurely or particularly small.

They put all the data into a computer and used it to build a prediction programme that could estimate the chances of a couple successfully making an IVF baby.  The new model seems to be more accurate than previous IVF prediction models, as it's newer and takes more factors into account. But the model is only based on looking at IVF cycles that have already happened, so the programme needs to be tested in a forward-looking study.

The scientists hope to gather more data over the coming years from couples going through the IVF procedure, and the researchers are now working on making the programme available online and even as a smartphone app to help them test it. At the moment it will only be suitable for couples who have had their infertility investigated, but if it holds up, it could be a useful predictor to help couples decide whether they want to go with through IVF, and some of the possible risks they may face.

02:56 - Tears manipulate men's moods

Tears are traditionally judged to be a visual display of emotion, and humans, it's claimed, are the only species to shed them. But now scientists in Israel have found that they can also carry chemical messages to alter the moods of others close by, an observation which fits with earlier studies showing that the composition of emotionally-shed tears differs significantly from the composition of tears produced in response to eye irritation.

Tears manipulate men's moods

Tears are traditionally judged to be a visual display of emotion, and humans, it's claimed, are the only species to shed them.  But now scientists in Israel have found that they can also carry chemical messages to alter the moods of others close by, an observation which fits with earlier studies showing that the composition of emotionally-shed tears differs significantly from the composition of tears produced in response to eye irritation. 

Entombment of Christ, 1672, in Saint-Martin Church in Arc-en-Barrois (Haute-Marne, France). Mary Magdalene.The new discovery, published in Science, was made by Edith Wolfson Medical Centre researcher Shani Gelstein and her colleagues.  They showed two female volunteers some tear-jerking film footage and collected the watery results as they ran down the womens' cheeks.  In a separate experiment they also collected saline solution dribbled down the same womens' cheeks to control for any odours that might be entering the tears from the skin.

These tear samples were presented in a blind fashion to the nostrils of 24 male volunteers who were asked to rate the sexual attractiveness of a series of female subjects shown in a collection of photographs.  The photographs were viewed twice, once while the subject was smelling the saline control and again during exposure to the emotional tears.  The researchers also measured the mens' testosterone levels during the study as an indicator of arousal.

Seventeen of the volunteers rated the same female faces as significantly less attractive when they viewed them whilst sniffing the tears compared with the saline. The subjects also had lower testosterone levels following tear exposure, and brain scans also showed a drop in neuronal activity in brain regions linked to mood when subjects sniffed the tears.

This suggests that, contrary to the prevailing view that tears are merely an outward display of emotion, in fact it appears that they also contain covert chemical signals that convey mood-altering messages to male recipients.  The team point out that there is ample opportunity for such signals to pass from a teary-person to a recipient.  "We hug a crying loved one, often placing our nose near teary cheeks, typically generating a pronounced nasal ihalation as we embrace."

However, the identity of the chemicals responsible for these effects remains a mystery, as does whether mens' or childrens' tears are capable of similar emotional chemicals manipulation...

05:55 - Chills of Musical Pleasure

Many of us have a certain piece of music that causes chills to run up our spines - music so good, it elicits a genuine physical reaction. Now, researchers at Montreal Neurological Institute and Hospital have been exploring the brain basis of this experience. Kat Arney spoke to Valorie Salimpoor from McGill University.

Chills of Musical Pleasure
Valorie Salimpoor, McGill University

Kat -   Now I am sure that all of us have a certain piece of music that causes chills to run up our spines.  Music so good, it elicits a genuine physical reaction.  Now, researchers at Montreal Neurological Institute and Hospital have been exploring the brain basis of this experience, and to tell us more, we're joined by McGill University's Valorie Salimpoor.  Hi, Valorie.

Music and the brainValorie -   Hi.  How are you?

Kat -   Great!  Now tell us a little bit about the background to this.  So what were you trying to find out with these experiments?

Valorie -   Well, we know that music has been around for a very long time.  We know that it's been around throughout history and in every single culture.  Evidence for this goes as far back as history has been recorded and we know that things that usually stick around for long periods of time are usually behaviours that are biologically adaptive, or necessary for survival.  But we are still somewhat unclear on how exactly music fits into this.  So, what we do know is that music makes us feel really good and in fact, the euphoric feelings produced by music have often been described as similar to the rush of very powerful drugs like cocaine, for example.  Interestingly, drugs like cocaine actually exert their effects on the dopamine reward circuit in the brain.  And the reason why this is relevant is because the system in the brain is actually a phylogenetically ancient system and it has evolved to reinforce highly adaptive behaviours such as eating and sex for example.  So when dopamine is released, these behaviours are strongly reinforced.

Kat -   So it's kind of the bit of the brain, the pleasure centre of the brain.

Valorie -   Exactly.

Kat -   So how did you test whether this pleasure centre is linked to listening to music?

Valorie -   Well we wanted to see if music is actually linked into the system and this is a hypothesis that's been around for a while.  So, a few researchers have attempted to examine this. People have found, with their colleagues, that when you're listening to pleasurable music, there are some hemodynamic changes in the regions of the brain that are normally involved in dopamine or take reward.  But the problem with that is, up until now, we didn't know if the neurotransmitter dopamine was actually involved.  So we used a procedure called PET.  This is Positron Emission Tomography and this uses radio ligands to determine how much dopamine is actually released and where.  So people came in and they brought in their own self selected music that was intensely pleasurable for them and when they listened to it inside of the scanner, we actually found that they released dopamine.  And this is sort of a big deal because the system is a very potent reinforcer and it actually, by definition, underlies our motivation and our desire to seek a reward.

Kat -   So they're basically getting a natural high from listening to these tunes.

Valorie -   That's exactly it, yes.  Except that there are no severe consequences like there would be with drugs for example.

Kat -   But one question I have.  I mean, music is such a powerful thing in our culture and how do you know that these people don't just, "Oh, I love this piece of Debussy because it was played at my wedding."  How do you separate whether it's just a nice memory or whether it's actually the music?

Valorie -   That's actually an excellent question because music has such tight links with our memory systems that it's really, really hard to separate out the two and music is often used to sort of stimulate these pleasurable memories.  So, the way that we tried to rule that out in our experiment is by doing extensive pilot testing where we asked people, is this in any way associated with a specific episodic memory in your life, for example, as you mentioned, your wedding or a summer in your life, or graduation, or some other happy time that they've had.  If that were the case, then we didn't use those participants or those particular stimuli in our experiments because we had to try to rule it out.  Having said that, this is something that can happen unconsciously.  People wouldn't necessarily be aware of the fact that they do have some sort of a memory associated with this piece of music.  So, in our next experiments, we'll be using new music that people have never heard before and try to see if we can replicate these findings with something that they can't have any previous memories associated with.

Kat -   So what is it in music that makes us have this emotional experience?  Is there any information about - is it a specific tune or chord sequences?

Valorie -   Well it seems to be somewhat different for different people which is really what's fascinating about it because it seems to be very much a cognitive reward.  It's almost as if our experience of pleasure to it is also is dependent on how we're following the tone sequences that we hear.  An example of this is that if you hear a single tone, that's not really pleasurable for you, but if you hear a series of these single tones over time, that can become some of the most pleasurable and intense experiences that humans have ever reported.  So, how exactly does this happen?  David Heron for example has a book called Sweet Anticipation and he explains this very nicely where we develop a sense of anticipation to where these notes are going to go, and then our expectations can either be confirmed or we may be surprised but either way, it seems like composers sort of know this and they try to manipulate our emotional arousal with the way that they're sequencing these tones.  This is probably why our appreciation of music is partly cortical or intellectual, or cognitive if you will. 

Our results actually provide very nice evidence to support this hypothesis because we found that right before we combined our PET procedure with fMRI so we can get some temporal information on what's happening in the brain as well.  We found that right before this peak emotional response which we measured by chills for example in our study,  participants were actually showing dopamine release in different regions of the reinforcement circuit that has very strong connections with the frontal cortex.  Now, the frontal cortex of the brain is a part that's highly developed in humans and it's basically what separates us from lower order primates and it houses complex thinking.  So, what we see here is evidence of this complex or abstract appreciation of an aesthetic stimulus which in this case is music, is also tapping into the same dopaminergic system that reinforces the most fundamentally rewarding and biologically adapted behaviours such as food and sex.  The same system also produces the same intense euphoric feelings of addictive drugs, such as cocaine.

Kat -   Wow!  That's absolutely fascinating and as a musician, I hope you find out what the key is, to making everyone love your music.  That is Valerie Salimpoor from McGill University in Canada and you can find more about that story -  it's published online in the journal Nature Neuroscience this week.

12:04 - Dental-drill cancelling headphones

For many, just the distant sound of a dental drill is enough to elicit a cold sweat, let alone having to endure it first hand during a filling. But now a new, noise-cancelling device developed by a London-based research team could help to take some of the pain out of the experience.

Dental-drill cancelling headphones

For many, just the distant sound of a dental drill is enough to elicit a cold sweat, let alone having to endure it first hand during a filling.  But now a new, noise-cancelling device developed by a London-based research team could help to take some of the pain out of the experience.

Inventor Brian Millar, from King's College Dental Institute, was initialy inspired to develop the new gadget by the efforts of the car-maker Lotus, who were working on a way to improve passenger comfort by using a sonic-cancellation system to remove unpleasant road noise yet leave passengers able to hear important sounds like emergency sirens or horns.

Dentist - Faroe IslandsThe new prototype device works similarly, cancelling out the high-frequency sounds of the dental drill whilst leaving the lower pitches - such as speech - untouched. Even better, it's designed to be compatible with the average personal MP3 player.  So a patient could simply plug the device into the headphone socket of their player, then plug their own headphones into the device and then carry on listening to their own music - or even the Naked Scientists podcast - with the drill sounds being subtracted around them.

The noise cancelling effect works by listening selectively to the incoming sound of the drill and then producing a soundwave in the headphones which is the mirror image of the drill noise, suppressing the sound.

Brian Millar is now looking for external investment to take the invention to market.  "The beauty of this gadget is that it would be fairly cost effective for dentists to buy, and any patient with an MP3 player would benefit from it, at no extra cost. What we need now is an investor to develop the product further, to enable us to bring this device to as many dental surgeries as possible, and help people whose fear of visiting the dentist stops them from seeking the oral healthcare they need."

14:59 - Going topless harms hearing

Despite their suave appeal, convertible cars could have to carry a health warning owing to the threat they pose to the occupant's hearing.

Going topless harms hearing

Despite their suave appeal, convertible cars could have to carry a health warning owing to the threat they pose to the occupant's hearing.

Writing in the Journal of Laryngology and Otology, St Louis University researcher Anthony Mikulec and his colleagues measured the noise levels experienced by passengers travelling in five different makes of cabriolet, including a Porsche 911, at a range of speeds and with the roofs both on and off. 

Convertible Jaguar E-Type, Hamburg.Guidelines relating to levels of noise exposure suggest that sustained exposure to sounds louder than 85 decibels (dB) is likely to permanently damage hearing, probably by metabolically stressing the hair cells in the inner ear where soundwaves are converted into brainwaves.

In the study, with the roof off and moving at about 55 miles per hour (88 km/h), three of the five cars were already exposing passengers to sound intensities close to this threshold.  When the speed was increased to over 70 miles per hour (120 km/h), sound levels at or above 85 dB were recorded in all of the cars, and in one model sustained levels of nearly 100 dB were measured.  This effect was negated when the roof was in place, with passengers experiencing sound levels of about 75 dB, well below the limit considered safe.

These results suggest that long car journeys in open-topped vehicles are likely to expose passengers to sustained noise of 100 dB - the equivalent of holding a running chainsaw - particularly when the traffic is heavy as this increases incidental noise, or if the car radio or music is played since this will be turned up even louder to compensate for the ambient sounds.

According to Dr Mikulec, "In light of the results of this study, we are recommending that drivers be advised to drive with the top closed when travelling for extended periods of time at speeds exceeing 85.3 km/h".

So, topless round town then, but not elsewhere...

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