"Yes, sound is a pressure wave that propagates in all directions, most of the time. A soliton is a pressure wave that does not change shape or intensity as it moves. This is not a theory, it is a proven phenomena found in nature. Solitons also exist in light waves and even water (some types of tidal bore). Basically, the shape of the wave causes it's energy to be funneled back into itself and not dispersed."

Science can't *prove* phenomena. It's used as a tool to build hypotheses into theories, which are subject to further testing. In this way we can provide evidence for how natural processes may work, but we can never be certain enough to call it "proof". There always may be more information generated in the future upon further testing which disproves our theory.

Dont'cha just love it!

Nature could not possibly have found a way to optimize using several variables for transmission!

And medical patients couldn't possibly have multiple issues at the same time.

No, No, far to inconvenient!

Being a physics student I am surprised by some of the replies to this article. For instance, Electrical Engineers should talk about electricity and not sound propagation.

Yes, sound is a pressure wave that propagates in all directions, most of the time. A soliton is a pressure wave that does not change shape or intensity as it moves. This is not a theory, it is a proven phenomena found in nature. Solitons also exist in light waves and even water (some types of tidal bore). Basically, the shape of the wave causes it's energy to be funneled back into itself and not dispersed.

Sound comes in different frequencies, which we hear as pitch. For instance, some voices are higher or lower depending on faster or slower frequency. Just as our eyes can only see certain wavelengths of light and can't see ultraviolet or infrared light waves, our ears can only pick up certain frequencies of sound. If there was a sound pulse from our nerves it could be outside this frequency and the amplitude so small (we're talking a scale of a nanometer) that no, we cannot hear our nerves.

This theory is misquoted a bit and if you read the paper that is linked in a comment above, it accepts that heat is produced and that electrical pulses are present. It simply says that electrical pulses cannot fully explain the observed changes in the volume and viscosity of the nerve during impulse. The theory says that the observed electrical pulse could be a byproduct of the mechanical motion of the nerve, and the myelin sheath contributes to heat release which is then almost perfect reabsorbed (which is the contradiction with thermodynamics).

Yes, the heart emits electrical impulses, but it moves too. You can attach an electrode to your arm and make it move, but screaming at it does nothing. I would infer that if the electrical signal were a byproduct of the mechanical motion, that such a signal could also cause mechanical motion in the nerve and thus move the arm. The nerve fibers that the sound wave moves through would have to be insulated (although not "perfect acoustic insulators") and only specific waves (solitons) would travel undisturbed. Otherwise, we'd all be flopping around uncontrollably from the sounds around us.

Here is my two cents worth being that i am an electronics engineer that designs professional audio products every day.
If the nerve impulses were sound waves they would propagate everywhere throughout the body due to some bloody obvious things.. Surrounding each cell is a given quantity of water and as we all know it happens to be a very efficient conductor of sound. Secondly any sound waves would happily radiate in all directions when they are reflected of any body that lies in its path. so for this theory to be worth a damn it would rely on the fact that the sheath is a PERFECT acoustic insulator and that the universe created a really funky anomaly for your theory to work.
I suppose that they will tell us that Phlogistin is responsible....
Hey try a MAGNETIC wave, it makes more sense and fits the model a touch better especially when it comes to thermodynamics.

I find the idea very interesting, however I wonder how they would explain our current exploitations of the human nervous system which rely on the presence of electrical impulses.

Hearing implants are designed to use electrical impulses to allow subjects to crank up amplification the same way you turn up the volume on a TV. Nerves have also been exploited in the brain so much as to allow for the replacement of eyes (http://www.mobilemag.com/content/100/102/C7184/) and elsewhere as in the addition of a bionic arm (http://www.washingtonpost.com/wp-dyn/content/article/2006/09/13/AR200609...). In any case, electrical devices are being used by subjects almost as intuitively as the organic parts they're meant to replace, which suggests that they are functioning in a similar way.

On the one hand, the human nervous system may adapt somewhat to the devices, but if it only functioned by way of mechanical waves, why would it provide electrical impulses just out of the blue?

If it weren't for these innovations, I would find their heat discovery fairly convincing. As it is, it seems to be yet another unexplained mystery of the life. Still, I'd love to hear more about the sound theory. Maybe they actually use a combination of sound and electricity. Maybe it's much more complex (or simple) than we ever imagined.

I love the new theory, but of course I am always up for popular beliefs being overturned. Besides, if nerves really were determined by electricity wouldn't they have been able to find a cure for RSD (Reflex Sympathetic Dystrophy) A progressive disease that attacks the nervous system giving the patient suffering with it sensations of burning in the hands feet and legs? Come on, open up your minds, next you people are going to cry the global warming is a crock full of beans as well!

I began to read this article with interest until I came to the statement "The physical laws of thermodynamics tell us that electrical impulses must produce heat as they travel along the nerve, but experiments find that no such heat is produced," says associate professor Thomas Heimburg...". At this point I sensed a disconnect between the quotation and the actual content of the paper. Its authors are well aware of the heat production associated with a nerve impulse, a phenomenon that has been known for decades. For example, they cite the the following article:
Abbott, B. C.; Hill, A. V.; Howarth, J. V. The Positive and Negative Heat Production Associated with a Nerve Impulse. Proceedings of the Royal Society of London. Series B, Biological Sciences, Volume 148, Issue 931, pp. 149-187, 1958.
So I am puzzled by the quotation given in the news release. The authors of the study have proposed a new mechanism for nerve impulse propagation in their attempt to overcome some of their perceived shortcomings in the Hodgkin-Huxley theory, which has a huge literature in its support. Certainly any theory is open to challenge, but Heimburg and his collaborators have a heavy burden of proof which (at least by my reading of their paper), they have not met, nor have others with various competing theories. It will be interesting to see how this plays out.

This theory seems to contradicts the entire structure of the nerve. Because in most cases with the human body everything is there for a reason. (with exception to the appendix) Nerves are equipped with a myelin sheath to help aid in the quickening of impulses sent between nerves. It aids as an insulator for the electrical impulses, which explains why impulses are slower on un-myelinated nerve cells. So with this theory it would make a major part of the nerve cell seemingly useless and for billions of cells in our body to have a completely useless feature seems overly far fetched.

Relatively loud sounds are audible in air. These are much much smaller amplitude and are contained waves in nerve fibers. Calling them sound waves just means that they're a certain kind of longitudinal wave in a medium. That's very different from them being macroscopic waves in air that our ears are sensitive to.

What ab the various NT and tranmission thru the synapses?

To dismiss out of hand without examination is the reason the earth was flat for so many years. The "Sound as a media for nerve transmission" theory could provide the solution as to how Acupuncture works

The entire idea of science is to look at a process, come up with a hypothesis that could explain it, and to then test the hypothesis via experimentation.

these scientists have come up with a hyposthesis and presumably will try to test it. it is an interesting idea, and understanding it requires knowledge of the biochemistry and biophysics of membranes, and the physics of sound in microscopic conditions. it may be hard to do the experiments. it may be impossible to produce evidence. but if they can accumulate data to support their hyposthesis, the burden of evidence will lead other scientists to use the idea as a reasonable explanation.

the number of people who laughed at this hypothesis in the preceeding comments is concerning. to ridicule a new idea is not part of the scientific process. it is at least bad playground behavior. worse, it turns knowledge into faith, an unassailable wall that stifles intellectual curiosity and creative thinking. history is filled with examples of how badly that turns out. if you don't think an idea is correct you should do the experiments to disprove it, or wait for the proponent to give evidence. in fact, you should do the same thing if you believe in the idea. it is the only way that science can move forward. remember einstein and quantum mechanics. the burder of evidence gives us an approximation of the truth, and every scientific idea is testable, by definition.

dogs can pick all many sounds that we cant. it depends on how loud the sound is

attach a frogs leg to a battery and it will twich. attach a frogs leg to a piano and it will do nothing.

Freezing is a state change from liquid to a more solid state. Depending on the additional items in an oil solution, it can be very high temperatures where this state change happens. The fulltext article (linked elsewhere in this chain of comments) spells things out in rather more detail.

The transducing of electrical to acoustic waves via solitons is not something new and was discussed in extensive detail by Frank Barr, who pioneered (alone) the concept of neuromelanin and its effect on information propagation in the nervous system. Barr FE. Melanin: the organizing molecule.Med Hypotheses. 1983 May;11(1):1-139. The hypothesis is advanced that (neuro)melanin (in conjunction with other pigment molecules such as the isopentenoids) functions as the major organizational molecule in living systems. Melanin is depicted as an organizational "trigger" capable of using established properties such as photon-(electron)-phonon conversions, free radical-redox mechanisms, ion exchange mechanisms, and semiconductive switching capabilities to direct energy to strategic molecular systems and sensitive hierarchies of protein enzyme cascades. Melanin is held capable of regulating a wide range of molecular interactions and metabolic processes primarily through its effective control of diverse covalent modifications. To support the hypothesis, established and proposed properties of melanin are reviewed (including the possibility that (neuro)melanin is capable of self-synthesis). Two "melanocentric systems"--key molecular systems in which melanin plays a central if not controlling role--are examined: 1) the melanin-purine-pteridine (covalent modification) system and 2) the APUD (or diffuse neuroendocrine) system. Melanin's role in embryological organization and tissue repair/regeneration via sustained or direct current is considered in addition to its possible control of the major homeostatic regulatory systems--autonomic, neuroendocrine, and immunological.

There was a soliton theory of muscle contraction put forth about 15 years ago and that never got anywhere, either. Maybe it was soliton sound wave that produced the ripping sound of my hernia in the gym recently... ;)

FREEZING NEURONS? "The scientists found that the nerve membrane has a freezing point, which is precisely suited to the propagation of these concentrated sound pulses." Proposing that the lipid membrane of the neuron and the seperate cell providing myelination are "freezing" to propagate sound waves needs some EVIDENCE.

People criticising this theory might do well to read the paper in which they spell it out.

Hmm. To put it in a simple way...How does one spell "Urban Legend"? I applaud you for the effort. But sometimes I have to shake my head in disbelief as to HOW brilliant minds can put all that mental super-goo to waste...? Really. One factor of science that is often omitted (I've been guilty of it), is relevance...nerve impulses, sound??? Come on...really.

Sound is audible. Why can't we hear all the noise our neurons are making?

Sound waves - they can't be serious?

This hypothesis has been around for decades and the study of it has failed to generate enough positive data to lead us to believe that sound waves instead of ion flux is how impulses are generated. Just because we don't know yet how many anesthetics work at the molecular level doesn't mean that they have to work by inhibting sound waves. We don't know how gravity works either but that doesn't mean that current theories of gravity are worthless, it just means we don't have the right foundation of knowledge or the right tools to understand it yet.

I don't know what this guy is up to, but we know exactly how nerves work. Do you have a link to the actual article?