Is the human jaw capable of producing infrasonic noises?

[Elite Jacob]

A while back I read a meterology textbook to learn about the atmosphere and on one of the pages there was a factoid about the human jaw resonating at an infrasonic frequency between .4-.8 mhz. I think it can be heard when you clench your jaw and release it. I believe this is relevant because most of information about infrasound I find talks about how it can cause anxiety and other phsyiological changes in the body, but finding the information about the jaw is difficult. Links would be awesome. I received an infraction from an admin. because I asked a question about this factoid and would like to know if it can be verified.

 

[mfb]

.4-.8mHz? This corresponds to a period of 20 to 40 minutes. I don't think there is any mechanical system in the body resonating at such a low frequency. In addition, "sound" with that period would be considered as atmospheric pressure variations and not as sound.

 

[Evo]

A while back I read a meterology textbook to learn about the atmosphere and on one of the pages there was a factoid about the human jaw resonating at an infrasonic frequency between .4-.8 mhz. I think it can be heard when you clench your jaw and release it. I believe this is relevant because most of information about infrasound I find talks about how it can cause anxiety and other phsyiological changes in the body, but finding the information about the jaw is difficult. Links would be awesome. I received an infraction from an admin. because I asked a question about this factoid and would like to know if it can be verified.

Your infraction was reversed, and your original post was nothing like this.

The clicks, pops, or grating sound when opening or closing the mouth. On average the symptoms will involve more than one of the numerous TMJ components: muscles, nerves, tendons, ligaments, bones, connective tissue, and the teeth.

These sounds, clicks, pops, etc... are clearly audible. Infrasound is under 20 Hz, you showed mHz, that wouldn't be right.

Discussion of human resonant frequency

By testing the response of the human body on a vibrating platform, many researchers found the human whole-body fundamental resonant frequency to be around 5 Hz. However, in recent years, an indirect method has been prosed which appears to increase the resonant frequency to approximately 10 Hz. To explain this discrepancy, experimental work was carried out in NTU. The study shows that the discrepancy lies in the vibration magnitude used in the tests. A definition of human natural frequency in terms of vibration magnitude is proposed

http://adsabs.harvard.edu/abs/2001SPIE.4317..469B

Usually any sound emmited below 20 hz can't be heard by the human ear.

http://en.wikipedia.org/wiki/Temporomandibular_joint_disorder

http://en.wikipedia.org/wiki/Infrasound

 

[BenG549]

A while back I read a meterology textbook to learn about the atmosphere and on one of the pages there was a factoid about the human jaw resonating at an infrasonic frequency between .4-.8 mhz. I think it can be heard when you clench your jaw and release it. I believe this is relevant because most of information about infrasound I find talks about how it can cause anxiety and other phsyiological changes in the body, but finding the information about the jaw is difficult. Links would be awesome. I received an infraction from an admin. because I asked a question about this factoid and would like to know if it can be verified.

If you're talking about 4-8Hz, that would make sense. I wrote a small section in my recent dissertation regarding the adverse health effect of environmental noise, including low frequency noise and infrasound. A lot of the adverse effect are attributed sleep fragmentation which has been shown to affect a number of human processes including waking psychomotor performance (van Dongen et al, 2003); memory consolidation (Stickgold, 2005); creativity (Wagner, et al 2004.); risk-taking behaviour (Mckenna et al 2007); signal detection performance (Basner et al. 2008) and will as a result, increase the risks of accidents (Barger et al. 2005; Scott et al 2007). Most of the effects such as anxiety are attributed to sleep disturbance as well as other socio-economic factors such as the fear of falling house price etc..

As for physiological effects, long term exposure to infrasound has been shown to have an effect on certain human cells (I know liver cells have been studied in this context) but it's not been studied extensively that I know of. As for jaw resonance... not sure what that is all about. Your mouth/vocal track has resonance that is responsible for the timbre of your voice and hence your accent, and bone conduction is why your voice sounds slightly different when you record it an hear it played back (most of what you hear of your own voice is 'filtered' somewhat from propagation though your bone structure). Other than this I'm not sure what you could be referring to.

Anyway for more information of the adverse effects of low frequency noise this article* will prove useful... Although infrasound is not well defined; sounds well below 20Hz are in fact audible at high enough levels but, off the top of my head, this is a level around 90+dB(G) where the G indicates frequency filtering used in infrasound assessments that reflects average audible thresholds (ISO7196, 1995)... although tonality might be lost below about 15/16Hz... I can safely say you are not producing this level of sound with your jaw alone. Anyway, this paper will tell you a lot about the general study of low frequency noise and it's effects. References for most of the citations above can be found in that paper, if you can't find them and want to know the full reference, or have any follow up questions, let me know.

* http://westminsterresearch.wmin.ac.uk/4141/1/Benton_2003.pdf

 

[Pythagorean]

.4-.8mHz? This corresponds to a period of 20 to 40 minutes. I don't think there is any mechanical system in the body resonating at such a low frequency. In addition, "sound" with that period would be considered as atmospheric pressure variations and not as sound.

Not to mention the wavelength. It's hard to imagine something as small as a human jawbone detecting something so large.

 

[Evo]

If you're talking about 4-8Hz, that would make sense. I wrote a small section in my recent dissertation regarding the adverse health effect of environmental noise, including low frequency noise and infrasound. A lot of the adverse effect are attributed sleep fragmentation which has been shown to affect a number of human processes including waking psychomotor performance (van Dongen et al, 2003); memory consolidation (Stickgold, 2005); creativity (Wagner, et al 2004.); risk-taking behaviour (Mckenna et al 2007); signal detection performance (Basner et al. 2008) and will as a result, increase the risks of accidents (Barger et al. 2005; Scott et al 2007). Most of the effects such as anxiety are attributed to sleep disturbance as well as other socio-economic factors such as the fear of falling house price etc..

Actually, the OP is claiming that the jawbone sends out infrasound. Not the effects of external infrasound on parts of the body.

His original OP

If the human jaw resonates at an infrasonic frequency do the rest of the bones in the body also resonate or is there something special about just the jaw bone. Also if the body emits these sound waves what effect on the surounding air pressure would it have, and would the more people also effect the amount of change in air pressure.

 

[russ_watters]

C'mon guys: I'm sure the OP meant megahertz, not milihertz (according to my spell checker, no such measure even exists, which isn't surprising). As typos go, not capitalizing the "M" is a pretty minor one here.

 

[Evo]

C'mon guys: I'm sure the OP meant megahertz, not milihertz (according to my spell checker, no such measure even exists, which isn't surprising). As typos go, not capitalizing the "M" is a pretty minor one here.

Yes, the op said infrasound = megahertz, infrasound is below 20 hertz. I believe only one member might have misread it.

 

[russ_watters]

Yes, the op said infrasound = megahertz, infrasound is below 20 hertz. I believe only one member might have misread it.

Heh - ok, so it was (probably) the OP's misunderstanding and not a typo...which I then missed. Still, I think correcting that misunderstanding would have worked out better...

Objects resonate at a frequency determined by mass and elasticity. A bone, being hard, would have a resonant frequency like (probably higher) than a hard piece of wood.

 

[BenG549]

Heh - ok, so it was (probably) the OP's misunderstanding and not a typo...which I then missed. Still, I think correcting that misunderstanding would have worked out better...

Objects resonate at a frequency determined by mass and elasticity. A bone, being hard, would have a resonant frequency like (probably higher) than a hard piece of wood.

Yeah, obviously even if we know the properties of bone it is difficult to establish a resonant frequency as the Jaw bone is coupled to other parts of the body (the rest of your skull etc) As you probably know, that will affect this, and the material around the bone probably acts as effective damping/absorptive material. So even if your Jaw was resonating at an audible frequency; firstly, it is not doing so of it's own accord, it obviously must be stimulated somehow so it's more likely the noise you hear is due to the initial impulse or noise as opposed to any subsequent resonance, plus if this resonance is audible whether the OP was referring to infra or ultra sound is almost irrelevant; in this context neither of those extremes are likely to be audible.