Compression of water (split from Waveguides)

[sreten]

Originally posted by MJL21193


Yes, sound travels through metals in a longitudinal wave.
No compression though - displacement.

Hmmm.......

I see your still stating the same inanity without any sensible proof,
because you cannot have one - because the above is simply wrong.
Carry on discussing how to be wrong and self-opinioniated.

/sreten.

[auplater]

Maybe it's like this "honorable mention" excerpt from Wiki..

"One 'Honorable Mention' (a man who attempted suicide by swallowing nitroglycerine pills, and then tried to detonate them by running into a wall)"

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

or perhaps this:

http://pinkfluffydust.livejournal.com/36518.html

[Sheldon]

I didn't mean to start a round of name calling. I'm truly curious, as the discussion didn't lead to the understanding that I would have expected. Let's not beat on anyone.

Sheldon

[auplater]

Who's calling names? I'm curious too... why, in the face of exhaustive explanations and spoon-fed treatises anyone would continue w/o remorse.

not to mention lame emails as well...

If the shoe fits...

[scott wurcer]

I think it's over

[despotic931]

Originally posted by Sheldon
I didn't mean to start a round of name calling. I'm truly curious, as the discussion didn't lead to the understanding that I would have expected. Let's not beat on anyone.

Sheldon

Yes, no one should be beaten on!

Originally posted by auplater
Who's calling names? I'm curious too... why, in the face of exhaustive explanations and spoon-fed treatises anyone would continue w/o remorse.

not to mention lame emails as well...

If the shoe fits...

I didn't get any lame emails! I don't think John is crazy, or dumb, or anything bad. He just has a different idea about the way that something takes place, and granted he has yet to prove that idea imo, that doesn't mean that he believes it any less. I am confused about why he started by saying compression did not take place when sound traveled through water then switched to stating that a small amount of compression does take place. As much as he seems to believe that our idea of the way sound travels through water is wrong, he doesn't seem to be so set in his own idea of how sound travels through water.

Originally posted by scott wurcer
I think it's over

I hope not!

[MJL21193]

Originally posted by scott wurcer
I think it's over

Not quite.

Originally posted by scott wurcer

You continue to miss the concept of impedance match. The air that "slops" around when a speaker moves is mostly wasted energy, the actual acoustic waves launched by a speaker is a small fraction of the total energy. The same is true when you speak of sloshing around water because it's "not constrained" this is not the propagation of sound waves. There is an unfortunate need for semantic clarity on the word wave in this context.

We are talking about how sound travels through a medium, not how it is first introduced. Impedance match has nothing to do with this "discussion".

Originally posted by scott wurcer

Again no effort to put actual numbers on concepts. Water is 1/10000 th less compressible than air. I have no problem with a 1 Pa pressure wave compressing water to 1 - .00048ppm of its volume (I think I got the number right) why do you?

Very well, but the pressures involved are in the microPascal range (typical sound wave).

Originally posted by scott wurcer

I might add the several hydrophone configurations are designed around the same principles as microphone arrays and would not function if the sound wave propagated by displacement rather than pressure/compression.

Originally posted by scott wurcer

I think the ultimate irony is that if you rolled the numbers propagation by displacement would probably involve a LOT more energy.

So, it is your contention that NO displacement takes place? Explain what happens to the energy that is dissipated in the medium.
How can a medium dissipate energy without a temperature change?

[scott wurcer]

Originally posted by MJL21193




Very well, but the pressures involved are in the microPascal range (typical sound wave).


How can a medium dissipate energy without a temperature change?

It all scales, it does not matter at all even nano Pascals. All lossy media attenuate a traveling wave by heat. One of those excellent references probably has a discussion re: water. RF waves propagate in a vaccum essentialy losslessly.

You accept the classical formula for the speed of sound, so think of a whale making a 20Hz sound and compute the wavelenth and then the energy to displace that much water.

[MJL21193]

Originally posted by scott wurcer



It all scales, it does not matter at all even nano Pascals. All lossy media attenuate a traveling wave by heat. One of those excellent references probably has a discussion re: water. RF waves propagate in a vaccum essentialy losslessly.

What happens to a medium when energy is dissipated by heat? Volume change (increase)?
So, it stands to reason that as sound travels through a medium the volume that this medium will occupy will increase. This is the definition of displacement.

Originally posted by scott wurcer

You accept the classical formula for the speed of sound, so think of a whale making a 20Hz sound and compute the wavelenth and then the energy to displace that much water.

How does a whale make sound?
A whale modulates the water pressure by pushing it through its blowhole. This, if I'm not mistaken, is similar to the way a pump would work by pressurizing the water.
As mentioned earlier, water can be pressurized without significant density change. Take the pressure changes at depth in the ocean - constant increase as you go down. Water can flow despite this pressure (current).

More later....

[scott wurcer]

Originally posted by MJL21193


How does a whale make sound?
A whale modulates the water pressure by pushing it through its blowhole.

More later....

No, you seem to make this up as you go along. Check out those SPLs for whale songs 223dB re 1 micro Pascal.