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Thread: Sound resonance frequencies

  1. #1 Sound resonance frequencies 
    Forum Professor leohopkins's Avatar
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    Does anyone know where I can get a list if sound resonance frequencies of different materials?

    Thanks


    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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    I don't think such a thing exists. Resonant frequency of materials is a function of mass, shape, and modulus of elasticity.


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    Indeed. All the pipes in a church organ are made of the same thing, but they resonate at different frequencies and thus produce different notes. You might could factor shape out by finding the resonant frequency of some specific shape in different materials, but I don't think that exists either.
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    Quote Originally Posted by Harold14370
    I don't think such a thing exists. Resonant frequency of materials is a function of mass, shape, and modulus of elasticity.
    Yes it does exist. That is how opera singers are able to shatter wine glasses for example. - They simply use their voice so that the note they produce reaches the same sound resonance frequency as the glass.

    - Like wise, this is how "sonic welding" is done. - The same sound resonance frequency as the metal is produced and the metal heats up.

    The initial question remains to anyone who knows of a useful website listing materials and their sound resonance frequencies. - Thanks
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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    Quote Originally Posted by leohopkins
    Yes it does exist. That is how opera singers are able to shatter wine glasses for example. - They simply use their voice so that the note they produce reaches the same sound resonance frequency as the glass.

    - Like wise, this is how "sonic welding" is done. - The same sound resonance frequency as the metal is produced and the metal heats up.

    The initial question remains to anyone who knows of a useful website listing materials and their sound resonance frequencies. - Thanks
    I don't think he was questioning whenever or not the frequency exist, but rather stating that if such a list was to be made, each material tested has to be under the same conditions.

    As for the list, I doubt such a thing exist. As the frequency changes with every little change in mass and shape, but it might exist for some materials if they have pretty static values.
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    Consider a guitar string. As you increase the tension on it, the resonant frequency increases. A heavier string of the same material, and tightened to the same tension, will have a lower frequency. So, you could not assign a single resonant frequency to the steel or gut material the string is made of.
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    I've never heard of "sound resonance frequencies"

    If you mean the "speed of sound" in different materials, here you can find how to calculate it:
    http://en.wikipedia.org/wiki/Speed_of_sound
    And here you find the required parameters for various materials, but the most materials also have their own wikipedia site and stiffness and density are usually listed.
    http://en.wikipedia.org/wiki/List_of...nts_by_density
    http://en.wikipedia.org/wiki/Bulk_modulus
    http://en.wikipedia.org/wiki/Young%27s_modulus

    If you mean resonance frequency (and most objects will emit sound when excited at resonance frequency), the other posters are right: it depends on the geometry. In the case of an organ, it only depends on the geometry, since it's the air that gets into resonance (ok it also depends on the composition of the gas).
    In your wine glass example: if you take another wine glass, you need a different frequency to break it. Even if you pour a little bit of water in the glass you'll need a different frequency.

    And concerning the sonic welding (or other sonic machining methods): I think it's the tool you get into resonance, not the workpiece.
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    Oh right. I overlooked that in the organ example. Not 100% true though, since they use specific materials in the construction of the pipes to get the sound the way they want it, but still 99% true.

    A xylophone or a guitar (as Harold mentioned) would be a better example.
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    Quote Originally Posted by MagiMaster
    Oh right. I overlooked that in the organ example. Not 100% true though, since they use specific materials in the construction of the pipes to get the sound the way they want it, but still 99% true.
    Since we're nitpicking: that's not to change the resonance frequency, but the amplitude of the harmonics (the timbre of the sound) :wink:
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    Okay,

    The reason for me asking this is that I know that waves of energy can be amplified, and projected, rather like light can with the laser. So the same must be with sound waves.

    I had an idea for a non-lethal weapon that would destroy buildings and bridges. Sound laser-type weapon that would transmit high intensity waves on a localised area of concrete to crack and destroy the structure.
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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    You might be looking for a sonic boom: move a sound source at the speed of sound and you've got yourself a nice an devastating pressure wave.
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    A strong enough sonic boom could do it, but for the original idea, it just wont work. Concrete is a mixture of different materials, and doesn't have a resonance frequency. As the sound passes through the concrete, it bounces off the many tiny interfaces between the different grains, losing any resonance or cohesion (and a lot of its power). Only very uniform materials in fairly uniform shapes exhibit strong resonances.
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    no, resonant frequency is a tricky thing to play with. it is impossible to generalize resonant frequency by material, because, as stated by everyone else, it depends also on shape and mass. Sound, as a weapon, is useless aside from the psych warfare it is already used for. Unless, of course, you have a nice giant, pure steel structure that you'd like to bring down. I think, the mythbusters did something on this as thought up by good 'ol Nikola
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  15. #14 Re: Sound resonance frequencies 
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    Quote Originally Posted by leohopkins
    Does anyone know where I can get a list if sound resonance frequencies of different materials?

    Thanks
    The wavelength at which resonance occurs is determined by the geometry of the problem -- length alone in the case of an organ pipe (you are looking at the first fundamental longitudinal mode. Frequecy is determined by the wavelength and the speed of sound. The speed of sound is determined by the material, in the case of gasses by the temperature molecular weight and ration of specific heats. In the case of solids the speed of sound is determined by the modulus and density.

    http://en.wikipedia.org/wiki/Speed_of_Sound
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    Quote Originally Posted by leohopkins
    Quote Originally Posted by Harold14370
    I don't think such a thing exists. Resonant frequency of materials is a function of mass, shape, and modulus of elasticity.
    Yes it does exist. That is how opera singers are able to shatter wine glasses for example. - They simply use their voice so that the note they produce reaches the same sound resonance frequency as the glass.
    But this isn't only due to the material the glass is made of, but also the size and shape of the glass. You could put two wine glasses made of the same glass next to each other, subject them to the same frequency and one would shatter and the other wouldn't. This would be due to small differences in the shapes of the wine glasses.
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    Here is a way to find out. Hit the object, and copy the tone it produces. As simple as that. The term you are looking for is "sympathetic resonance" I do not know if that is a scientific term, but it is used in the musical world, take for example the symp-atar, a guitar with sympathetic strings that run underneath the regular strings, inside the neck and body, they resonate at different frequencies depending on what notes you are playing, giving a chromatic haunting sound. There are Norwegian violins made like this, I think they are the original sympathetic instrument. If you take the mute hammers off of a piano and play a note, you will hear all the other notes that it "sympathizes" with as well

    A concrete wall has a tone, it is just very very very very very very low. You would need an ultra contra bass horn... you can make one I forgot how. but it's something you plug in and let loose, it usually destroys itself and if it's in a room that is seeled it will shatter windows and tear doors of hinges, crack drywall, etc.

    this damage has nothing to do with the tone, but the implosion of air created by the sound waves. such a machine would not last long enough to destroy stone work though it might make some cracks bigger... it's progress!

    since it is very hard to separate overtones with the ear, you will probably need a computer to record the sound and then take whichever frequency is loudest.

    I don't know if that is actually how you would do it, I've never tried and never looked it up, but that is where I would start.


    There is this old anarchist lamentation that goes "Shame concrete don't burn"

    if you figure out a solution to this problem, please let me know
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    no. not quite. It's more like the concrete has several tones that all distort each other. Each of those tones may be low, but, since it is a heterogeneous mixture, they are not coherent and will not produce a resonant frequency, sorry.
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    In fact, a concrete wall is rather stiff, so I doubt the sound would be low. If you hit a concrete wall, the sound is usually rather high btw. Arcane_Mathamatition also has a strong point.
    The resonance frequency of an entire building, however, is very low (very high mass). But for obvious reasons engineers take measure to prevent large structures from having pronounced resonance frequencies (type "tacoma bridge" in youtube if you want to know why).
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    1) It ain't so simple as to have a list.

    2) Listen to what Harold said.

    The sound wave needs to propogate through the material in such a way that it's reflection is in phase with the incident wave, and thus accentuates the motion. (if I remember right..)

    Fill your bathtub to about 30% then make waves with a regular motion, you will quickly find one speed where very little effort is needed to make larger waves, and if you continue the water will spill out. Note the frequency and write it down.

    Next refill the bath with motor oil and repeat the experiment, you will find the same effects occur but at a different frequency.

    Lastly (and it will be last..) repeat the experiment using gasoline to obtain yet another frequency.

    Now repeat the whole thing at your Gran's house (if she has a different sized tub)
    and you get to see that like Harold said there are quite a few factors.

    If there is a list of resonances, it should give precise data on size, shape, composition, temperature, atmospheric pressure, method of excitation, etc etc as well as any frequency data.
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    is the high sound you hear when you hit a concrete wall from the concrete wall or from the object you hit it with?

    if you have 3 concrete blocks of different size(assume they are all the same in other aspects) the smaller one will be higher than the bigger one won't it
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    in response to the points about buildings and low frequencies bringing them down: is that not what earthquakes are? Earthquakes can be seen as just sound waves with enormous amplitude and low frequencies are they not?
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    Partially, yes, and as Bender said, engineers take as much care as possible to prevent exactly such a resonance. (High winds can also cause some of the same effects.) On the other hand, the accelerations caused by an earthquake can do plenty of damage even without resonance. Of course, engineers take this into account too.
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    Well, yes. That's one of the main reasons modern engineers take wind resonance into account.
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    Actually the Tacoma Narrows Bridge did not collapse because of resonance:

    http://www.ketchum.org/billah/Billah-Scanlan.pdf

    It is one of those popular science factoids that get repeated until it is so ingrained that even textbooks support this view. Just like the idea that the Coriolis Effect causes toilets to flush in opposite directions in the northern and southern hemispheres:

    http://www.snopes.com/science/coriolis.asp
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    Quote Originally Posted by ScienceWizard
    Actually the Tacoma Narrows Bridge did not collapse because of resonance:

    http://www.ketchum.org/billah/Billah-Scanlan.pdf

    It is one of those popular science factoids that get repeated until it is so ingrained that even textbooks support this view. Just like the idea that the Coriolis Effect causes toilets to flush in opposite directions in the northern and southern hemispheres:

    http://www.snopes.com/science/coriolis.asp
    As with most failures there are usually more than 1 cause, resonance played a part clearly as did aerodynamics a shift in the design of either could have prevented the problem. At the end of the day Until the Millenium footbridge in London no other bridge (that I am aware of ) suffered this effect (the London bridge had to be modified to ease severe swaying in moderate winds).

    Since galloping Gerie Aerodynamics and resonance have been taken into account when building suspension bridges, thus one may say "since the inclusion of resonance factors into bridge design no other suspension bridge has failed catastrophically" from which one may draw one's own conclusions as to the effect of resonance at Tacoma Narrows.
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    I think the Millennium Footbridge started swaying up and down because of the foot traffic, not because of wind forces.
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    Quote Originally Posted by harvestein
    in response to the points about buildings and low frequencies bringing them down: is that not what earthquakes are? Earthquakes can be seen as just sound waves with enormous amplitude and low frequencies are they not?
    Earthquakes provide the capability to excite some oscillatory modes, but in earthquake-prone areas large buildings are often isolated and damped to prevent damage from resonance. However, earthquakes can also provide high amplitude displacements and just plain high acceleration and that is where much of the extensive damage originates. On soils that tend to have high amplitude displacement the damage is greater than on rocky areas -- old lake beds as with Mexico City (or Salt Lake City) can be vulnerable.
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  30. #29  
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    Quote Originally Posted by ScienceWizard
    Actually the Tacoma Narrows Bridge did not collapse because of resonance:

    http://www.ketchum.org/billah/Billah-Scanlan.pdf
    That paper is really splitting hairs rather finely except for specialists. They are quite correct in that one cannot describe the failure accurately using only the notions of forced oscillations of a system described by a second-0rder ordinary differential equation, as in elementary textbooks. But that description is still qualitiatively useful.

    They are correct in that the failure mechanism was that of an insufficiently damped oscillatory mode excited by wind and amplified by non-linear aerodynamics effects that created a positive-feedback situation. This is rather akin to the case of a poorly damped closed-loop system with inadequate stability margin (poles being too close to the right-half plane in some terminology). Nevertheless the effect of thjis non-linear positive-feedback loop was to excite a dynamic mode that led to failure -- and that excitation of the mode can be described as a resonance. It is not the resonance of the system with the initial forcing function, but it is a resonance that is created by the interenal system dynamics, fundmentally related to fluid flow.

    So, I can agree with the authors that when the Tacoma narrows disaster is discussed in detail with an advanced audience the precise nature of the system dynamics and interactions needs to be presented accurately. But I disagree that the use of the Tacoma Narrows Bridge disastere as an example of resonant behavior is inappropriate for pedagogical purposes in an elementary class on physics or differential equations. It gets across the point that resonances are important and that students of science and engineering need to pay attention to such details.
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  31. #30  
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    Quote Originally Posted by ScienceWizard
    Actually the Tacoma Narrows Bridge did not collapse because of resonance:

    http://www.ketchum.org/billah/Billah-Scanlan.pdf
    I think the authors of that article are splitting hairs rather closely, except for an audience of specialists.

    They are correct, and I can agree that the failure mode of the Tacoma Narrows Bridge is not accurately described by the simple model of a second-order ordinary differential equation with a forcing functin approaching the natural frequency of the system. The failure mode was indeed driven by a non-linear aerodynamic aspect of the dynamics of the structural system that produced a positive-feedback loop and led to failure. That is rather akin to the situation in linear control theory in which there is inadequate stability margin -- a pole is just too close to the right-hand plane.

    Nevertheless, the effect of the internally developed positive-feedback loop is to excite and internal resonance and thereby achieve amplitudes that result in failure.

    In an advanced class or seminar with an experienced and sophisticated audience these distinctions are worthy of discussion. It is important in that setting that all of the technical details be discussed precisely and that the subtleties be understood.

    I must, however, disagree with the authors that the use of the Tacoma Narrows Bridge disaster in an elementary class in physics or ordinary differential equations is inappropriate. The failure was closely related to the notion of resonance. The disaster is a useful pedagogical tool to call attention of the students to the phenomena of resonance and to the importance of understanding and considering it in practical problems. At that level the distinction between resonance directly resulting from the external forcing function and resonance that is internall generated by a system non-linearity that couples with a mode of response is not particularly important. I do agree that it is not appropriate to distort the truth by stating that the von Karman vortices did something that they simply did not do -- but there is no need at the introductory level to go into the details of the fluid dynamics. The issue of resonance is a real one, and it can be accurately addressed without going into details of fluid flow and turbulence.
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