has anyone ever tried the soda bottle thing?

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Rocket Boy

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heres the quote from the sae site

"The helmholtz resonator (named after a Mr Helmholtz who discovered it) can best be demonstrated by taking a normal soft drink bottle and blowing over the mouth of the bottle - a note is produced. Now place some cotton wool in the bottle and try again. You will notice the note has reduced- well not really, the note is produced but the wool absorbs the resonance and turn the sound energy into heat! Imagine, if you lined a whole wall with bottles of various sizes, all filled with insulation material. You would now have a low-mid (200 - 500Hz depending on the bottle size) absorbing wall that as well as absorbing the low mids would also reflect or diffuse the high frequencies. I haven't tried it yet but it would be worth trying if you are short of cash because bottles are cheap."


has anyone ever actually tried this? i was thinking of attaching some pieces of particle board using hinges, lining it with bottles like this... and then recording inside of that. i think that maybe sounds kinda ridiculous, but would this sound cool? has anyone tried anything dealing with using plastic and glass bottles like this?

do you even think it would be worth the effort?
 
Probably be more practical to get a part-time job flippin' burgers, and put the money into a better looking version - unless you just have no life, and really like weird things... Steve
 
yeah... i actually thought it might look kinda cool :-P i mean, would it work as well as a regular slat resonator? i'm mostly concerned with how well this would actually work.
 
I accidentally tried this by leaving dozens of mostly consumed beer bottles lying around the studio. Instead of cotton, the small amount of stale beer proved the perfect culture for a fuzzy mold that grew on top.

Did it work? I couldn't tell. My head was pounding too hard to tell.
 
"i'm mostly concerned with how well this would actually work." -

If that's your main thing, I'd go for the slat resonator. It will be much easier to figure out (using the calculator on the SAE site) what your actual resonant values are than with a bunch of nearly unmeasureable bottles... Steve
 
You know I did try knightfly's little experiment depicting depth vrs volume on frequency resonance. Was very cool to see <or hear> it work.

Space
 
I would think it would work but I'm guessing you haven't really thought through the practicalities of attaching bottles to wood and then hinging it so it is movable without actually knocking off all the bottles not to mention the weight and the fact that you wouldn't be able to have a very tight angle on the hinges because you would have a 6-12" thick absorber. Then there's the trouble of finding all those differently sized bottles...
 
Rocket Boy said:
heres the quote from the sae site

"The helmholtz resonator (named after a Mr Helmholtz who discovered it) can best be demonstrated by taking a normal soft drink bottle and blowing over the mouth of the bottle ...

do you even think it would be worth the effort?
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No, it wont work!

I've been constructing a bunch of speakers, many transmission liners amongst them. The Dämmmaterial (hmm i guess in english it's called absorption material) is only good for reducing the speed of the sound. Higher frequencies will be stronger absorbed and low frequencies will be transmitted with lowered air travelling speed.

The point is, to reduce the speed + redirect the sound wave in the way, that the the original and the redirected sound wave will annihilate each other.

This is the way wall pannels work.
The problem is to design the redirections to work for as many frequencies as possible...

The problem with the bottles is, that you have to force the waves to flow thru the bottles either by focusing the flow over the bottles or providing enough surface.
 
Reduce the speed of sound?:eek: In air? Thats a new one on me.

The problem with the bottles is, that you have to force the waves to flow thru the bottles either by focusing the flow over the bottles or
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Oh puuuuuuuuuleeeeeze. Spare me.:rolleyes:
fitZ
 
RICK FITZPATRICK said:
Reduce the speed of sound?:eek: In air? Thats a new one on me.
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In air the speed of sound is aprox. 326 m/s.
In acoustic absorbing wadden the speed will decrease down to 280 m/s.

In water the speed of sound will be a few meters per second. This is the reason why everything you can hear underwater is very dull.
 
In water the speed of sound will be a few meters per second. This is the reason why everything you can hear underwater is very dull.
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Actually the speed of sound in water is well over 1,000 M/S (1,480 M/S to be exact).

I am a Diagnostic Medical Sonographer and took a great deal of (ultra)Sound Physics. Alot of it translates pretty well in audio applications.
 
In water the speed of sound will be a few meters per second. This is the reason why everything you can hear underwater is very dull.
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I must be underwater.:rolleyes: And how did you gather this little gem of data struberg? Must have been the same type of experiment that generated these results huh?
In acoustic absorbing wadden the speed will decrease down to 280 m/s.
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scooterb wrote:
Actually the speed of sound in water is well over 1,000 M/S (1,480 M/S to be exact).
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I love it. Thanks scooterb.:cool:

Doggone, I know a guy thats got the Brooklyn Bridge for sale. Cheap. Any takers?
fitZ:D
 
I love it. Thanks scooterb.
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Glad I could help.....I actually got up and dusted off an old text book just so I could give you the exact number.

FYI if any one is curious the average spped of sound in human tissue is even faster...1540 Meters/Second.

I'll take the speed of sound for $200 please.
 
The Romans used to line the sides of their theatres with earthen jars of different sizes that were filled with wool - they acted like the bottles and lowered the reverbtime of the low mids.

cheers
john
 
Hello John, sure is good to see you here. Sorry to hear about your equipment. Must have been a hell of a storm. Got one coming right now:eek: By the look of the clouds it will be a dooooozy.

Hey John, are you sure those earthen jars weren't filled with wadden to slow down the sound?:D (just kidden, and yes, I know I'm a smartass)
 
if the speed of sound is higher in water than in air, wouldn't that mean that underwater things would be higher-pitched? i don't doubt you're right, i'm just trying to understand the physics of the situation.
 
Not sure, I never tried to sing under water. Thing is, this would be kind of hard to measure. Pitch is more a function of the cavity that's vibrating to make the sound than it is the medium it's traveling in.

For example, the reason "helium voice" works is that helium has a speed of sound that's nearly three times that of air, so the reason your voice sounds like a chipmunk if you snort enough helium, is that your vocal cavities are now filled with helium so they resonate the same as if they were only about 40% of their normal size.

Where sound is merely traveling in a straight line, you may hear it sooner but its pitch is determined by the source, not the medium.

If that were not the case, the sound you hear on the other side of a gypsum wallboard wall would be partially supersonic, since the speed of sound in gypsum is almost 20 TIMES what it is in air - 1130 fps vs. 22,300 fps... Steve
 
Where sound is merely traveling in a straight line, you may hear it sooner but its pitch is determined by the source, not the medium.
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That is exactly right.

Pitch (aka frequency) is determined by the source.

The speed of sound is determined the the media it is traveling through.

Sound absorbtion and reflection is determined by interfaces of differing media the sound wave encounters.

The efficiency of sound transmission in a single media is determeind by how stiff and how dense the media is.

How effeciently the sound transfers from one media to another depends on a type of impedance value that is determined by how much percentage the interface of the two media reflects the sound waves versus how much is transfered to the next media.

Scatering sound waves (type of reflection) decrease the concentration of the sound energy.
 
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