Actually, the pitch of any resonant object goes down when immersed in water?
.....at least to the person who is listening to it through the air outside the water.
I can't figure out the physics of this phenomenae...........any fluid physicists out there to
help me explain this to my students?
.....at least to the person who is listening to it through the air outside the water.
I can't figure out the physics of this phenomenae...........any fluid physicists out there to
help me explain this to my students?
posted by:
|
-
physical vibration is very susceptible to friction then sound wave vibration which experiences less friction traveling through liquid or a solid then air. if you fire a 50 and a 20 caliber bullet into water the 20 will travel further then the 50.
-
-
I see what you are saying but how does that translate to the audible pitch of any instrument going
down the further it is immersed in water.
Can you explain further?
(and thanks for responding at all) -
-
my guess would be that as the water slows the physical vibration it also slows the pitch of the sound waves it produces and they go down.
we feel like this is backward because if you put the end of a ruler over the edge of a desk that you twang on and then slide it back it makes a higher pitched sound as the exposed part gets smaller... but with your gong the whole thing is still vibrating... it's just that the part under the water is having a hard time vibrating and behaves the way that a material of a greater mass would and as you dunk it further more of it behaves that way.
just a guess....i'm no engineer.
-
-
-
I'll jump into the fray - - -
first, a gong probably has multiple resonances.
water has damping ( no pun intended ;-] ) effect.
-
I don't have an explanation about the pitch going down... but I'm pretty sure that the speed that the waves are travelling through the medium has nothing to do with it... as the sound may be hitting you sooner... but the frequency is still the same.
-
-
all resonant objects go down noticeably in pitch when immersed in water.
I don't mean to look a gift horse in the mouth (thanks for all your thoughts)
but I haven't heard a really good explanation yet. -
-
"The frequency of a wave is determined by the frequency of the source, therefore the frequency is generally known or at least unchanged by the medium through which it is travelling."
above is a better articulated explanation of what I was getting at... that the water doesn't change the frequency of the sound because the sound is travelling through water... but it is changing the frequency because the object is in the water... which is essentially slowing down the movement of the object as it vibrates.
but alas... this tribe tends to lean towards religion as opposed to actual science!
:-) -
-
lol, I hear you, Jeremy.
Where are the damned scientists when you need them.
It's a curious thing............the water, do to physical enertia, slows down the object and yet, it is a much more
effecient mode for transmitting the sound.
A facquaintance of mine had one ear above the water and one ear below the water line during an explosion in a Navy Seal
excercise and completely had his hearing blown away in the ear that was under the water.
-
I'm guessing here but it seems the reason is due to density and the fact that these are two very different mediums. My assumption is that the pitch drops because there is more mass to move in water a liquid medium versus air a gaseous medium...
-
-
> My assumption is that the pitch drops because there is more mass to move in water
Precisely correct. Water provides more resistance to physical motion (vibration, in this case) than does air. So the motion is slowed as you immerse a vibrating tuning fork in water, lowering the perceived pitch. And increasing it's perceived volume, were you to have one ear under the water!
That same density accounts for the fact that vibration is more readily transmitted over distance also. As the molecules are closer together in water (or wood!) than air, they are (statistically) more readily affected (excited) by their neighbors.
An analogy to consider is that there is no sound in space because there is (almost) zero medium available to conduct or spread the oscillations. Conversely, if you were chillin in MJ's oxygen chamber, as you increased the ambient pressure, Thriller would become even more annoying than usual. :)
The same sound played from a Walkman 10' away from you in Death Valley would sound louder than if it were played 10' from you atop Everest. In Death Valley you'd continue to hear it much longer as you moved away from it's source also.
All because of the density of the conducting medium.
Does that help with the intuitive disconnect at all?
-
-
-
-
-
as several people have pointed out, the speed sound travels, and frequency, are different domains.. so, there isn't a relationship.. but, in understanding why sound moves more quickly thru water, wikipedia can help us.. :)
en.wikipedia.org/wiki/Speed_of_sound
"The transmission of sound can be explained using a toy model consisting of an array of balls interconnected by springs. For a real material the balls represent molecules and the springs represent the bonds between them. Sound passes through the model by compressing and expanding the springs, transmitting energy to neighboring balls, which transmit energy to their springs, and so on. The speed of sound through the model depends on the stiffness of the springs (stiffer springs transmit energy more quickly). Effects like dispersion and reflection can also be understood using this model.
In a real material, the stiffness of the springs is called the elastic modulus, and the mass corresponds to the density. All other things being equal, sound will travel more slowly in denser materials, and faster in stiffer ones. For instance, sound will travel faster in iron than uranium, and faster in hydrogen than nitrogen, due to the lower density of the first material of each set. At the same time, sound will travel faster in iron than hydrogen, because the internal bonds in a solid like iron are much stronger than the gaseous bonds between hydrogen molecules. In general, solids will have a higher speed of sound than liquids, and liquids will have a higher speed of sound than gases.
Some textbooks mistakenly state that the speed of sound increases with increasing density. This is usually illustrated by presenting data for three materials, such as air, water and steel. With only these three examples it indeed appears that speed is correlated to density, yet including only a few more examples would show this assumption to be incorrect."
peace
-cpr -
-
Let me try to theorize.
Sound is generated by "something" like a hammer hitting a bell and is carried by something else, like air or water.
The bell is the sound generator and the pitch is related to the size and material. In the case of comparing the pitch of air and water as the carrier, we must take into account that both have density of molecules and are becoming a part of the mass that is the generator. Just as the hammer is also influencing the pitch.
Therefore the Mass of the bell + air is different than the Mass of the bell + water and it can be expected that the pitch would differ.
....but I don't claim to be a scientist because I believe that the unproven also exists. :)
-
-
Unsu...
I am an architect and Cymatics researcher who would like to give our question a shot.
If something exists, it vibrates from which we can conclude that all things visible and invisible, audible and inaudible vibrate. Using a chemical reaction as a comparison, when we combine two or more vibrating things, a new harmonic results. This is true for tangible objects and intangible sounds. Some are harmonious and some are not but there is always more than one measure which is why this gets complicated in relation to our standard human scale.
There is always a planetary and even astrological vibes impacting any object as well, but these are generally stable and predictable so we can treat these as constants. The physical world is relativistic so there is harmony in relation to the cosmos and the Earth as well there is local harmony. A chord on the piano might replicate cosmic harmonies and the fact that it exists demonstrate local harmonies while discordant sound is locally harmonious though cosmically discordant. Being clear on our measure must become part of our language. I see these as different scales of reality and occurring simultaneously and do not underestimate beliefs which impact what we allow ourselves to understand and experience. The 2012 phenomena is a rare exception and very very important to understand but not the point of this response.
The pitch of the metal is actually the pitch of the air vibrating around the metal. The pitch of water is a slower and a more dense frequency akin to the Shumann Resonance of the Earth. The harmonic of the metal in the water creates a new vibe that is slower than vibrating air and faster than 7.8 Hz (and rising). The sound you hear which was in the air (the ear is an evolved mechanism to hear in the air as opposed to whales and dolphins that hear in the water up to 80 octaves I understand) but is now in the water and is therefore a slower (lower) frequency due to the combined vibe and your particular orientation.
Getting smaller....sound (phonons) do not bend like light (photons). At the subquantum level, photons are contiguous and continuous contrary to what we see at our scale of phenomenal reality. Imagine all objects and the air alight with electrical activity! That is what is actually going on! Inside the photon, an energy balance goes on which has it's own internal structure and is therefore electromagnetic. A phonon on the other hand is a quantum of vibration that will mechanically oscillate any matter in it's path so it's presence is dependent on photonic matter. The phonon is a vibration within matter or sound energy and is carried within a photon. When combined these are called Gluons. Sound organizes and integrates all matter so it can be thought of as the grammar of presence while photons can be thought of as the words. We hear energy in relation to movement but never as it exists as such except in rare moments of clarity or what seems like an advanced state of perception that some people have achieved.
Gluons surround and protect protons and neutrons and true to it's name, it's the binding glue within which the memory of the cell's journey is recorded. The subparticle reminds the gluon which energy level it should be counting (jumping between scales of reality). Bringing this back up the the human scale of things, the sound we hear depends upon two sources; the memory of the gluon inside the submerged metal and the memory of the cells in our body having been previously vibrated by the metal in the air. We do not ever experience life directly for this reason but rather the distinct hybrid of ever new expressions of matter. the water 'hears' this sound differently than you do.
Now, explain what I just said to me!
