Tag Archives: noise

Sound-absorbing nanofoam

In these increasingly noisy days (there’s construction going on around me), news of a cheaper, easier way to dull the noise is very attractive. From a June 25, 2018 Far Eastern Federal University (Russia) press release on EurekAlert,

The breakthrough material reduces a noise level by 100% more efficient comparing to standard analogs, cutting the level of noise transmission by 20-22 dB. The new foam reacts to sound waves not only of high but also of low frequencies, which can damage human health. A young scientist from the Far Eastern Federal University (FEFU) took part in the development.


Alexey Zavjalov, postdoc, researcher at the Academic Department of Nuclear Technologies School of Natural Science, FEFU, worked as a part of the international team of Russian and South Korean scientists under professor S.P. Bardakhanov. Alexey’s research performance led to the creation of nanofoam – the new noise-absorbing composite material. The results of the work are published in ‘Applied Acoustics’.

‘The problem of noise is the problem of modern technogenic civilization. In South Korea, cities are equipped with round-the-clock working stationary and mobile networks for noise levels monitoring. The urbanization level of such territorially small countries as South Korea is much higher than in Russia. However, in our country this problem is still crucial for big cities,’ – explained Alexey Zavjalov. – ‘The development of new noise-absorbing materials is especially interesting for the automotive industry. Modern people spend a lot of time driving cars and the noise level inside the vehicles’ directly determines the quality of life. For East Asian countries, the issue of noise control is relevant for high-speed rail lines.’ Porous materials are excellent sound absorbers but their noise-absorbing properties can be significantly enhanced by nanoporous grit injected into the foam structure and formed internal channels in it. Alexey Zavjalov has developed approaches for saturation of macroporous foam material with nanoporous grit.


Along with the rapid development of nanotechnology, there have been many attempts to mix nano- and microsized materials to create a modified material with enhanced strength, elastic, dynamical and vibrational properties. The acoustic parameters of such materials could not be fundamentally enhanced thus far.

Foam materials are most often used for soundproofing purposes. They provide the proper quality at a reasonable cost, but until today have been effective against high-frequency noise only. At the same time, low frequencies can be much more harmful to human health.

Infra- and low-frequency vibrations and noise (less than 0.4 kHz) are most harmful and dangerous for human health and life. Especially unfavorable is their long-lasting impact, since leads to serious diseases and pathologies. Complaints on such oppressions exceed 35% of the sum total of complaints on harmful environmental conditions.

The foam material, developed by Russian and Korean scientists, demonstrated promising results at medium frequencies and, therefore, more specialized low-frequency noise tests are needed.


The improved acoustic characteristics of the newest hybrid nanofoam were obtained by additional impregnation of the standard off-the-shelf sound-absorbing foam with porous granules of silica and magnetite nanoparticles. The porous foam was immersed in nanopowder suspensions in the liquid, subjected to ultrasonic treatment and dried.

The nanoparticles granules formed in the result can be compared structurally to a widely known class of materials – aerogel. It has not only excellent thermal insulation properties but also has a good noise-proof. However, aerogels are quite expensive and complex when used in structures. The new material, created according to the scheme developed by the FEFU researcher, is structurally similar to aerogel but is free of such shortcomings as a high price and engineering problems.


The mechanism of sound absorption of a new foam is based on the fact that its sound-absorbing surface is significantly scaled due to the presence of a large number of nanopores in the particles injected, as well as the location of these particles in the foam matrix in the form of distinct channels. Nanoparticles dissipate the energy of a sound wave transforming it into heat. The soundproof properties of the material increase.

Scientists found out that the composite structure is most effective for noise reduction. Thin layers of foam impregnated with nanoparticles are connected to each other in a “sandwich”-construction. This design significantly improves the soundproof properties of the resulting material. The outcome of the study also suggests that the more foamy material is impregnated with nanoparticles, the better it’s sound absorption is.

‘In some approximation, any material can be represented as a network of weights connected by springs. Such a mechanical system always has its own frequency bands, in which the oscillations propagate in the system relatively freely. There are also forbidden frequency bands in which the oscillations rapidly fade out in the system. To effectively extinguish the transmission of oscillations, including sound waves, the materials should be alternated in such a way that the fluctuations that propagate freely in the first material would be in the forbidden band for the second layer,’- commented Alexey Zavjalov. – ‘Of course, for our foam material, this idealization is too crude. However, it allows us to clearly illustrate the fundamentally conditioned necessity of creating a “sandwich” structure.’


The study showed the effectiveness of the method of foams impregnation with nanosilica or nanomagnetite, which form granules up to several hundred micrometers (in accordance with the pore sizes of the modified foam material) and having pores about 15 nm. This small addition provided a more complex and branched 3D network of nanochannels which led to an additional absorption of noise energy.

Due to the method used, the noise absorption efficiency was achieved in the range of 2.0-6.3 kHz and at lower frequencies 0.5-1.6 kHz. The degree of absorption was increased by 60-100% and the sound transmission was reduced by 20-22 dB, regardless of the type of nanofiller.

‘There is room to further improve the sound absorbing properties of the new material for medium and low frequencies using the” active control” strategy’. – Alexey Zavjalov comments on the plans for further development of such an important scientific topic. – ‘First of all, this refers to the materials obtained by using a magnetite nanopowder. Active noise protection systems have long been used in the world. The main idea is to detect the noise acoustic fields “online” and to generate sound waves in antiphase by means of loudspeakers. That allows achieving a significant reduction of noise in a given area. Concerning the nanofoam, it’s proposed to adapt this approach and to actively exert on a material saturated with granules of magnetite nanoparticles by magnetic fields. This will achieve even better noise reduction.’

Here’s a link to and a citation for the paper,

Hybrid sound-absorbing foam materials with nanostructured grit-impregnated pores by S.P.Bardakhanov, C.M.Lee, V.N.Goverdovskiy, A.P.Zavjalov, K.V.Zobov, M.Chen, Z.H.Xu, I.K.Chakin, D.Yu.Trufanov. Applied Acoustics Volume 139, October 2018, Pages 69-74
https://doi.org/10.1016/j.apacoust.2018.04.024 Available online 23 April 2018.

This paper is behind a paywall.

If you have difficulty seeing the press release on EurekAlert, there is a June 26, 2018 news item on a Russian news site, RSF News and there is an edited version in a June 26, 2018 news item on Azonano.

Café Scientifique (Vancouver, Canada) and noise on Oct. 27, 2015

On Tuesday, October 27, 2015  Café Scientifique, in the back room of The Railway Club (2nd floor of 579 Dunsmuir St. [at Seymour St.]), will be hosting a talk on the history of noise (from the Oct. 13, 2015 announcement),

Our speaker for the evening will be Dr. Shawn Bullock.  The title of his talk is:

The History of Noise: Perspectives from Physics and Engineering

The word “noise” is often synonymous with “nuisance,” which implies something to be avoided as much as possible. We label blaring sirens, the space between stations on the radio dial and the din of a busy street as “noise.” Is noise simply a sound we don’t like? We will consider the evolution of how scientists and engineers have thought about noise, beginning in the 19th-century and continuing to the present day. We will explore the idea of noise both as a social construction and as a technological necessity. We’ll also touch on critical developments in the study of sound, the history of physics and engineering, and the development of communications technology.

This description is almost identical to the description Bullock gave for a November 2014 talk he titled: Snap, Crackle, Pop!: A Short History of Noise which he summarizes this way after delivering the talk,

I used ideas from the history of physics, the history of music, the discipline of sound studies, and the history of electrical engineering to make the point that understanding “noise” is essential to understanding advancements in physics and engineering in the last century. We began with a discussion of 19th-century attitudes toward noise (and its association with “progress” and industry) before moving on to examine the early history of recorded sound and music, early attempts to measure noise, and the noise abatement movement. I concluded with a brief overview of my recent work on the role of noise in the development of the modem during the early Cold War.

You can find out more about Dr. Bullock who is an assistant professor of science education at Simon Fraser University here at his website.

On the subject of noise, although not directly related to Bullock’s work, there’s some research suggesting that noise may be having a serious impact on marine life. From an Oct. 8, 2015 Elsevier press release on EurekAlert,

Quiet areas should be sectioned off in the oceans to give us a better picture of the impact human generated noise is having on marine animals, according to a new study published in Marine Pollution Bulletin. By assigning zones through which ships cannot travel, researchers will be able to compare the behavior of animals in these quiet zones to those living in noisier areas, helping decide the best way to protect marine life from harmful noise.

The authors of the study, from the University of St Andrews, UK, the Oceans Initiative, Cornell University, USA, and Curtin University, Australia, say focusing on protecting areas that are still quiet will give researchers a better insight into the true impact we are having on the oceans.

Almost all marine organisms, including mammals like whales and dolphins, fish and even invertebrates, use sound to find food, avoid predators, choose mates and navigate. Chronic noise from human activities such as shipping can have a big impact on these animals, since it interferes with their acoustic signaling – increased background noise can mean animals are unable to hear important signals, and they tend to swim away from sources of noise, disrupting their normal behavior.

The number of ships in the oceans has increased fourfold since 1992, increasing marine noise dramatically. Ships are also getting bigger, and therefore noisier: in 2000 the biggest cargo ships could carry 8,000 containers; today’s biggest carry 18,000.

“Marine animals, especially whales, depend on a naturally quiet ocean for survival, but humans are polluting major portions of the ocean with noise,” said Dr. Christopher Clark from the Bioacoustics Research Program, Cornell University. “We must make every effort to protect quiet ocean regions now, before they grow too noisy from the din of our activities.”

For the new study, lead author Dr. Rob Williams and the team mapped out areas of high and low noise pollution in the oceans around Canada. Using shipping route and speed data from Environment Canada, the researchers put together a model of noise based on ships’ location, size and speed, calculating the cumulative sound they produce over the course of a year. They used the maps to predict how noisy they thought a particular area ought to be.

To test their predictions, in partnership with Cornell University, they deployed 12 autonomous hydrophones – devices that can measure noise in water – and found a correlation in terms of how the areas ranked from quietest to noisiest. The quiet areas are potential noise conservation zones.

“We tend to focus on problems in conservation biology. This was a fun study to work on, because we looked for opportunities to protect species by working with existing patterns in noise and animal distribution, and found that British Colombia offers many important habitat for whales that are still quiet,” said Dr. Rob Williams, lead author of the study. “If we think of quiet, wild oceans as a natural resource, we are lucky that Canada is blessed with globally rare pockets of acoustic wilderness. It makes sense to talk about protecting acoustic sanctuaries before we lose them.”

Although it is clear that noise has an impact on marine organisms, the exact effect is still not well understood. By changing their acoustic environment, we could be inadvertently choosing winners and losers in terms of survival; researchers are still at an early stage of predicting who will win or lose under different circumstances. The quiet areas the team identified could serve as experimental control sites for research like the International Quiet Ocean Experiment to see what effects ocean noise is having on marine life.

“Sound is perceived differently by different species, and some are more affected by noise than others,” said Christine Erbe, co-author of the study and Director of the Marine Science Center, Curtin University, Australia.

So far, the researchers have focused on marine mammals – whales, dolphins, porpoises, seals and sea lions. With a Pew Fellowship in Marine Conservation, Dr. Williams now plans to look at the effects of noise on fish, which are less well understood. By starting to quantify that and let people know what the likely economic effect on fisheries or on fish that are culturally important, Dr. Williams hopes to get the attention of the people who make decisions that affect ocean noise.

“When protecting highly mobile and migratory species that are poorly studied, it may make sense to focus on threats rather than the animals themselves. Shipping patterns decided by humans are often more predictable than the movements of whales and dolphins,” said Erin Ashe, co-author of the study and co-founder of the Oceans Initiative from the University of St Andrews.

Keeping areas of the ocean quiet is easier than reducing noise in already busy zones, say the authors of the study. However, if future research that stems from noise protected zones indicates that overall marine noise should be reduced, there are several possible approaches to reducing noise. The first is speed reduction: the faster a ship goes, the noisier it gets, so slowing down would reduce overall noise. The noisiest ships could also be targeted for replacement: by reducing the noise produced by the noisiest 10% of ships in use today, overall marine noise could be reduced by more than half. The third, more long-term, option would be to build quieter ships from the outset.

I can’t help wondering why Canadian scientists aren’t involved in this research taking place off our shores. Regardless, here’s a link to and a citation for the paper,

Quiet(er) marine protected areas by Rob Williams, Christine Erbe, Erin Ashe, & Christopher W. Clark. Marine Pollution Bulletin Available online 16 September 2015 In Press, Corrected Proof doi:10.1016/j.marpolbul.2015.09.012

This is an open access paper.

Science and music festivals such as Latitude 2015 and some Guerilla Science

Science has been gaining prominence at music festivals in Britain if nowhere else. I wrote about the Glastonbury Festival’s foray into science in a July 12, 2011 posting which featured the Guerilla Science group tent and mentioned other of the festival’s science and technology efforts over the years. More recently, I noticed that Stephen Hawking was scheduled for the 2015 Glastonbury Festival (he had to cancel due to personal reasons).

The 2015 Latitude Festival seems to have more luck with its science-themed events. according to a July 22, 2015 posting by Suzi Gage for the Guardian’s science blogs,

Why do people go to music festivals? When I was 18 years old and heading to Reading festival the answer was very much ‘to listen to Pulp and Beck in a field while drinking overpriced beer and definitely not trying to sneak a hip flask on to the site’. But I’ve grown up since then, and so, it seems, have festivals.

At Latitude this weekend, I probably only watched a handful of bands. Not to say that the musical lineup wasn’t great, but there was so much more on offer that caught my attention. The Wellcome Trust funded a large number of talks, interactive sessions and demos that appeared both in their ‘hub’, a tiny tent on the outskirts of the festival, but also in the Literary Tent at the heart of the festival and at other locations across the site.

The programming of the science content was imaginative, often pairing a scientist with an author who had written on a similar topic. This was effective in that it allowed a discussion, but kept it from becoming too technical or full of jargon.

Dr Robin Carhart-Harris, an expert in psychedelics, was paired with Zoe Cormier, author of ‘Sex Drugs and Rock and Roll’ in the Literary Tent, to discuss the use of psychedelics as ‘medicine for the soul’. [emphasis mine] Robin was very measured in his description of the trials he has been involved with at Imperial College London, being clear that while preliminary findings about psilocybin in treatment-resistant depression might be exciting, there’s a long way to go in such research. Talking about drugs at a festival is always going to be a crowd pleaser, but both Robin and Zoe never sensationalized.

A highlight for me was a session organised by The Psychologist magazine, featuring Professor Sarah-Jayne Blakemore and Fiona Neil, author of The Good Girl. Entitled ‘Being Young Never Gets Old’, it claimed to ‘debunk’ teenagers. …

Gage’s piece is a good read and I find it interesting she makes no comment about a literary tent at a music festival. I don’t know of a music festival in Canada that would feature literature or literature and science together.

Guerilla Science

I highlighted Zoe Cormier’s name as a participant (born in Canada and living in London, England) as she is a founder of Guerilla Science, the group I mentioned earlier with regard to the Glastonbury Festival. A science communicator with some fairly outrageous events under her belt, her and her co-founder’s ‘guerilla’ approach to science is exciting. I mentioned their annual Secret Garden event in a Aug. 1, 2012 posting where they sang and danced the Higgs Boson and otherwise celebrated elementary particles. The 2015 Secret Garden Party featured rest, noise, and neuroscience. (Perhaps it’s not too early to plan attendance at the 2016 Secret Garden Party?) Here’s an excerpt from this year’s lineup found in Louis’ July 15, 2015 posting on the Guerilla Science website,

Friday [July 24, 2015]


12:00 – Rest & Noise Shorts

Crash, bang, shush, zzz… four short talks about rest and noise from artist Zach Walker, psychologist Will Lawn and neuroscientists Ed Bracey and Melissa Ellamil.

13.00 Speed, Synapse… Go!

Two teams go head-to-head in a competition to see whose neurotransmitters can move the fastest. What happens when cocaine, marijuana and ketamine are introduced? Join us for some fast and furious neuroscientific gameplay.

15.00 Craft a Connectome

Help us transform the Guerilla Science tent into a giant model brain with a tangle of woolen connections. Neuroscientists Julia Huntenburg and Melissa Ellamil will be on hand to conduct our connectome and coax it into a resting state.

16.00 Sound, Fire and Water

We test out our new toy: a fire organ that visualises sound in flames! Join engineers from Buro Happold and artist Zach Walker as we make fire, water and cornstarch dance and jump to the beat.

Saturday [July 25, 2015]

11.00 Hearing the Voice

Philosopher Sam Wilkinson explores the idea of the brain as a hypothesis testing machine. He asks whether thinking about the mind in this way can help explain mental illness, hallucinations and the voices in our heads.

15.00 – The Unquiet Mind

Hallucinations are our contact with the unreal but are also a window into human nature. Neuroscientist and clinical psychologist Vaughan Bell reveals what they tell us about brain function and the limits of human experience.

Sunday [July 26, 2015]

12.00 Phantom Terrains

Frank Swain and Daniel Jones present their project to listen in to wireless networks. By streaming wi-fi signals to a pair of hearing aids, Frank can hear the changing landscapes of data that silently surround us.

13.00 Rest and Nose

Join chemists Rose Gray and Alex Bour and neuroscientist Ed Bracey to explore the links between relaxation, rest and sense of smell. Create a perfume to lull yourself to sleep, help you unwind and evoke a peaceful place or time.


For anyone interested in Guerilla Science, this is their website. They do organize events year round.