Why Does Sound Propagate?

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God.

notauser said:
I liked that when I typed it too.. I was thinking about Einstein's quote "If mathematics are the language of the universe, then algabra is the language of God.."
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Try using yours and his ( If wave mechanics is the sound of the universe, then algebra and mathematics is the language of God.)


Wow.

That would make God and the Universe (Relative)


kv
 
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Zen zere vere two...


That's all kind of a "Zen" way of thinking about it and there are many examples of such thinking. For example, we think of time as past, present and future. We think of the past as what has happened, the present as what's now happening and the future as what's going to happen. But, there is a "reality" to it. For example, there is no present. It exists only as a concept...it has no dimension. It's the demarcation between the past and future. It's like the geometric concept of a line which has only length. The minute you draw a line, it's a solid object with width and thickness. The past is fixed and unchangeable and, since the future will become the past, it's also fixed and unchangeable. We like to fool ourselves into thinking that the things we do can change the future but, in fact they only serve to ensure it.

Your concept of frequencies and wavelengths already existing and only needing to be "expressed" is really the same as saying that you need to do the actions needed to make them happen like everybody else thinks of them.

You can be as, Zen-like as you want when thinking LEDs. Certainly, the constituent parts of a red LED (the gallium and arsenic and plastics and copper and tin, etc.) have all been around as long as the universe and so are composed (ultimately) of primordial hydrogen. But, that line of reasoning, while it might be a clever mental exercise, isn't really very practical. At least for someone trying to build practical LEDs.

As regards the drudgery vs. pleasure of practicing music, at the level of Carnegie Hall orchestras, believe me, it's a serious and competitive job for those guys. The New York visitor asked a local, "How do I get to Carnegie Hall?" The answer, "Practice, practice, practice".

I don't know what kind of music you play but, if you don't practice, practice practice, it's probably not all that good.

I do have to say that I'm always on the lookout for bits and pieces of music I can use (not professionally so get those $ out of your eyes) for things like background on my YouTube videos and the like. No, I'm not looking for the (c)rap, acid, metal or "screaming lead" stuff. So, if you have a selection of pieces that you'd just like to have heard on occasion, let me know.
 
Check Please...

notauser said:
I'm about at the extent of my comfort level.. I haven't done much nitty gritty work with waves in a long time..
I gotta stress again though the convenience of learning the math principles behind this..
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I fully realize that there are limits that I can take these things in forums such as this. Especially, being the proverbial math moron I am. But, I appreciate your input and analysis. I do have to confess that I had hoped to beat down, to the lowest common denominator that I need for understanding, the answer to the post topic.

We've re-affirmed, over and over that sound does indeed propagate but...not why or how. I am not convinced that there isn't a simplified, verbal, non-mathematically entangled rendition that will at least give a reasonable conceptual answer.

As regards me becoming a math wizard. Sure, both me and the cat.

Per "flowery prose"...there is a language of God...and, it aint, algebra. And, it aint pretty...
 
Resonance, Simple harmonic motion, and restoring forces.. Read up on that and it may dawn on you that I've explained how/why..
 
Still at the periphery

killivolt said:
Simple Harmonic Motion | Sounds Amazing | AS/A Level Physics Revision | University of Salford - A Greater Manchester University


Ok, so what it's simple. But the math is incredibly difficult when applied to other Models.
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It's worse than that, kv (and, notauser). Yes, that link is a good and simple description (complete with animated examples) and it makes a nice remedial review of the kinds of stuff people in electronics deal with all the time (remedial even for me!). But, while it does a fine job of explaining:

notauser said:
Resonance, Simple harmonic motion, and restoring forces.. Read up on that and it may dawn on you that I've explained how/why..
Click to expand...

it does absolutely nothing to explain why the effect propagates. Even all of the examples are in fixed space with no hint, in verbage or graphics, of it so much as having even a tendency to "go anywhere", much less a mechanism for how it might propagate, as sonic energy, through a medium such as air.

In other words, it makes no attempt to answer the question I posed in this thread. So, no. It hasn't "dawned" on me.
 

crashsite, Please refrain from what I've pulled you into because that was my contribution. It was not a reference to his publications or what he may have on the subject.

I just found this site and thought they produced a representation putting a lot of work into the idea's and principles. You may want to consider how many people may be dragged to this site and not all of them understand they way most do or the way you do.



Elementary my dear Watson.



kv
 
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I thought I was done ranting...but, I was wrong...

killivolt said:
crashsite, Please refrain from what I've pulled you into because that was my contribution. It was not a reference to his publications or what he may have on the subject.
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The site you recommended deals with exactly the topics that were suggested that, if I would only read up on them, explain the answer to my question but, kv, let me be clear, this post is a general "rant" and is not directed at you in any way.

What the site did was reiterate that, when it comes to sound, people just can't seem to get past wave analysis of repetitive, cyclical events; the interchange of potential and kinetic energy over time, etc..

Now, I'm not saying that the answer may not indeed lie in that mechanism but, when I ask how it relates I just can't seem to get an answer beyond more exhortations that I go and study these waves more.

I can't say that I haven't learned things during the course of this thread because I have. But, frankly, I have no more of an idea of how/why sound propagates through a medium today than the day I asked the question.

Maybe even worse (or perhaps better) is that there are additional phenomena that I hadn't considered in the past that seem to muddle my understanding of the subject even further. And, maybe even worse than that will be my need to try to sort them out in this thread since there is a certain and heavy censure awaiting me if I attempt to ask them in a new thread (since the question must have already been answered since there was a pountless thread dedicated to it).

Hopefully, anyone who has sufficient interest to read these kinds of forums will see, in my efforts, a desire to get the answer (in the form and at the level that I'm able to understand it...which I sincerely believe is the form and level that a LOT of people need to really and genuinely understand it). And, perhaps they can add their own inputs (as some have).

I do have to say that I was more than just a little disappointed when someone with the reputation of, Nigel Goodwin came out and pronounced the whole thread as being, "pointless". In school, we were told that the only stupid question is the one you don't ask. Of course my teachers did not frequent the Electrotech Online forums so what did they know, huh? I can't say that I was surprised when Nigel opted to ignore my request that he should stop the need for the thread to continue by simply posting the answer.

Okay, if there's somebody out there that I haven't ticked off, i apologize. I didn't intentionally mean to leave anybody out.

I have to say that I really hate making posts like this because they take up space without dealing with the topic. But, sometimes you need to chop wood and let the chips fall where they may...even if those chips serve to make you a pariah. Heck, it might even get me banned for being a troublemaker.

So, no, kv...this is NOT pointed at you in any way. It just happened that it was your post that was the quoted launching point.
 
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On the fringe.

crashsite, Note taken. I'm just a bit of a stickler when maybe not of your intention, to include someone else in the simple explanations I offered. Even he and I have a degree of difference in what we understand. Even you have more than I do I think I just don't want to offend anyone by association.

It just seemed to me that somehow we were combined and my simple minded approach's and shouldn't reflect as to the nature of conversation you had with other (people) who clearly have more to contribute than I could.

As to Nigel. Well he's Nigel and I understand why he say's what he say's. It may not be within desirable content. And maybe those who are netted by web-crawlers and those luring words. So, I might be asking the question, who are the people we would like to attract to the site + who would benefit most from this site.

This is not a physics forum but the need for such learning exists for any Burgeoning Engineers. Which is maybe why he didn't shut it down.

Besides I'm really digging the idea of building A Van de Graaff generator.

It's so freaking cool.


kv
 
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Hope springs eternal


I couldn't agree more. And, that's what drew me to this site rather than a "physics forum". The notion that the people here are electronics first and physics second and thus have more of an appreciation for the nuts and bolts and practical aspects of it.

BTW: You've already built a Van de Graf generator. It's just that it looked less like a piece of lab equipment and more like a piece of carpet, a pair of rubber-soled shoes and a brass door knob. Actually, with the new anti-static carpet treatments, it's very possible (depending on how old you are), that you may not have ever built the accidental, impromptu Van de Graf machine.
 
When sparks fly.


Ha,ha. If you've read anything about my name on the site you are correct, if you want to look at it that way.


(killivolt, blue) nice and sparky.


kv
 
crashsite said:
.

Your concept of frequencies and wavelengths already existing and only needing to be "expressed" is really the same as saying that you need to do the actions needed to make them happen like everybody else thinks of them.
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No, not really. "Everybody else" isn't the issue. With the discovery of any anomaly there comes the responsibility to use it to the greatest benefit. I'm not sure what LED it was (I am thinking the Blue one) but Kyocera did the work. I'm pretty sure that the concept was there but the method was the thing that had to be discovered. Once the method was available the Blue LED (anomaly) happened with some regularity especially with the production of their LED laser printer.

There are many other "discoveries" that could prove the point I'm making. X-Rays existed before they were seen on photographic film. So, in following, there are many other things that exist for which a repeatable anomaly hasn't been seen yet. Things aren't brought into existence just by thinking of them but when we do see something pathetically easy to duplicate, e.g., growing penicillin, we take the Zen initiative and say, "Why didn't I think of that?"

I agree with you in that time is not a definable constant but you have to admit it does come in handy when we boil those eggs. On the extremes, the time line is a little hazy but those segments are dimensional to an extent.

Plus, in keeping with the potential of this thread, I'm also not so sure that sound travels in waves as previously thought.

I 'll make a confession. This morning I was "thinking" that sound just might travel in a vacuum but at such a speed that we can't perceive it, i.e., too fast to hear... like the speed of light.

---P
 
Dream Interpretation


From the wording of your initial post, I got the impression that you thought that the waves always existed and just needed to be tapped into. But, now I see that you mean that the physics is there to generate the waves, and there are natural forces that generate them and it's necessary (sometimes) to build devices to detect or exploit them. Additionally, there are waves that do not exist in nature and require devices to be fabricated to produce them. For example, the red color at around 630 nm abound in nature but, 630 nm waves that are generated by a red LED must be fabricated.

I don't think there's any argument about that. Your X-ray example is a good one. X-rays existed since the early universe at least and continue to this day but, it took some discovery and analysis to exploit them.

I do think it would be necessary to redefine sound in order to have it travel in a vacuum. It's like hearing blue or tasting C#. You'd need to redefine hearing and tasting since our senses simply don't respond to them such that would allow those actions. Again, back to X-rays. Even though we were bissfully unaware of X-rays, until they were discovered, they still affected us in the ways that physics dictated (increased cancer rate for example).

If the question is: Is there some mechanism by which sound waves on one side of a vacuum can somehow appear on the other side. Well, who knows? Maybe there's some as yet undiscovered linkage between sonic and electromagnetic energy that would make it possible...or some completely undiscovered phenomena.

That makes it science fiction. Of course, one must keep in mind that some of today's science was science fiction only a few years ago so, I guess the byword of the day is..."dream on".
 
If you understood SHM, then you'd understand the relationships between restoring force, and period, and you'd understand that the higher the frequency, the higher the restoring force, thus the propagation of sound..

Sorry to be a math nazi, but it really does fit..
 
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The Chasm

notauser said:
If you understood SHM, then you'd understand the relationships between restoring force, and period, and you'd understand that the higher the frequency, the higher the restoring force, thus the propagation of sound.
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I searched, "restoring force" and found what I was expecting. The force that tends to return something that was "stressed" (for lack of a better word), back to it's unstressed state. A typical example was the force of gravity trying to pull a pendulum back to its neutral position.

Period, as I learned it, is the reciprocal of frequency. I didn't try to Google it because it has so many definitions from menstruation to dots at the ends of sentences to an exclamation of finality...period!!!

Please pardon my thick headedness but, in my feeble mind there is a gi-normous gap between restoring forces/periods and sound propagation.

I can accept that molecules in motion can be made to move in specific directions and that they can bump into each other and, in that way, cause a disturbance to move through a medium such as air. I can also accept that even those suppositions may be wrong.

I can suppose that, since the speed of sound has a fairly specific and predictable velocity, that there's some sort of "resonance" involved in the process of sound propagation. But, I'm lacking an explanation of the mechanism by which these things happen.

I'm sure you see it differently, but, I go back to my Ohm's Law analogy. Ohm's Law allows you to quantify values and is essential for electrical design work...but, it does nothing to explain how electricity works. How the very components of the atom have the electrical charges and how voltage and cureent and resistance/reactace relate to moving the electrons around and the nature of materials and configurations of materials to control it.

Of course, one comes away with a very elementary and simplistic view of electrictiy from that apprach but, at this point in things, I'd be satisfied with that level of understanding of sound propagation.
 
I'm proud of ya dude, you looked into the math.. I'll let you sit on that for a while before I try to expand.. Better for you because sometimes things just need time to click, better for me because I just woke up, and can't see straight yet..
 
Bridging the Abyss

notauser said:
I'm proud of ya dude, you looked into the math.. I'll let you sit on that for a while before I try to expand..
Click to expand...

Dag-nabbit...I screwed up again. I was trying to promote the idea of explaining the "mechanics" of it conceptually, with verbage, rather than mathematically. Math has it's place and I do use it on an almost daily basis...when I need to quantify something (power dissipated by an electrical component, how much I can save by buying 3 cans of soup rather than one, the question to the occasional Jeopardy math answer, etc.) but, I'm convinced that there's a description that tells about sound propagation that doesn't rely on mathematical modelling.

You've given some clues and I believe you may have more of them than you may realize.
 
But to understand it in verbal terms, you still need a few concepts that make themselves most clear via mathematical description.. SHM, and restoring force.. When you realize that the restoring force determines the period/frequency independantly of mass you'll see how its just like a simple pendulum..
 
Rate of Change


I know that Galileo showed that the rate of acceleration of an object, under the influence of gravity, is independent of it's size or mass (the 32 feet per second per second thing) so, I'm supposing that the pendulum (with gravity as its restoring force) is subject to that bit of physics as well. I suppose it would also be reasonable to assume that there might be other "forces" out there that would have naturally similar effects on things as well...

Perhaps something like the hairspring in a wrist watch. I know that the grandfather clock is usually "adjusted" by moving the mass on the pendulum arm slightly up or down and the wrist watch by adjusting the tension on the hairspring.

In electronics, crystals, cavities, L/C, L/R and R/C networks, etc. also have natural rates and resonances. In somthing like optics it gets even more hinky. But, each sort of has it's own "methodology" for determining it's natural rate of change. Presumably, the very air itself might have a natural rate or frequency that somehow imposes itself on things that happen within an air mass.
 
And do you understand the intricacies of how any of those actually work? Have you worked with RL/RLC circuits?
 
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