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Is noise like water?

Old 03-13-2019, 02:07 PM
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Default Is noise like water?

What I mean is water will take the path of least resistance, well does sound follow the same principals? Can noise be funneled to a given destiny all the while reducing the noise to other places?
I get this noise barrier thing and why that works, but it's not quite the same thing as I'm trying to ask.
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Old 03-13-2019, 02:13 PM
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Simple answer is no. Sound waves move out from the sorce in a 360* pattern. Walls, baffles trees etc can slow the waves but they will travel all directions thru the same medium at the same speed. The only way to change that without a physical barrier is to alter the density of the matter the sound is travelling through
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Old 03-13-2019, 02:30 PM
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Originally Posted by Garett View Post
What I mean is water will take the path of least resistance, well does sound follow the same principals? Can noise be funneled to a given destiny all the while reducing the noise to other places?
I get this noise barrier thing and why that works, but it's not quite the same thing as I'm trying to ask.
Sound travels through a medium. (Atmosphere) The atmosphere certainly varies in density from place to place. Wind can move sound, disperse sound, and concentrate sound. So can changes in humidity, atmospheric pressure. There are acoustic shadows in nature.

The answer to you question is Yes. Path of "least resistance?" I don't know what "resistance" to pressure waves means.
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Old 03-13-2019, 02:46 PM
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Sound can be directed to some extent; but certainly not like a fluid. The external part of our ears do a bit of directing of the sound. Also notice the parabolic reflectors on the football sidelines that focus the sound onto a microphone.
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Old 03-13-2019, 02:51 PM
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As a wave... I believe sound would be able to be manipulated like RF (radio frequency) waves throughout waveguide in a radar system.
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Old 03-13-2019, 02:53 PM
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Sound waves are energy (pressure) waves moving through a medium such as air or water. To an extent they can made directional, but very hard to eliminate sound waves moving out 360 degrees from the source. Think of a loudhailer - it’s designed to be loudest directly in front, but you can still hear someone using it from any direction.

It can’t however be contained like fluid in a pipe or channel.
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Old 03-13-2019, 03:09 PM
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Very possible if you use two Solo cups and a string.
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Old 03-13-2019, 03:09 PM
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Originally Posted by Garett View Post
What I mean is water will take the path of least resistance, well does sound follow the same principals? Can noise be funneled to a given destiny all the while reducing the noise to other places?
I get this noise barrier thing and why that works, but it's not quite the same thing as I'm trying to ask.
my Bose wave system funnels sound quite nicely.
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Old 03-14-2019, 06:21 AM
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Old 03-14-2019, 08:11 AM
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Originally Posted by mikeloew View Post
Tweeters are by nature are directional, this is nothing new, but I think I understand the reason why you posted that up....360° thing.

Last edited by Garett; 03-14-2019 at 08:21 AM.
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Old 03-14-2019, 08:21 AM
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Ok, let's provide an example for my original question.

A dishwasher is installed in a cabinet, on the floor, with a counter top above it.
"If" one were to replace the wooden floor with a steel grate type screen would a majority of the sound created by the dishwasher go down instead of trying to penetrate the cabinet walls and the counter top? In effect making the ambient db levels lower?

Oh I get this idea of using a sound deadener on the cabinet walls and the underside of the counter top plus using additional sound deadening insulation around the dishwasher but could the noise levels be further reduced by providing the noise generated to go downwards into the basement?
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Old 03-14-2019, 08:40 AM
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Yes, it certainly can be directed. Look at the audio tubes used on old ships. Just a pipe from the helm to the rudder or engine room and you'd yell in one end to "talk" to the person on the other end.

There are also many examples of focusing sound. Look at the arch at the old rail station in St Louis. Whisper at one end and someone can hear you clearly about 50' away, as if they were standing right next to you.
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Old 03-14-2019, 08:43 AM
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Originally Posted by Garett View Post
Ok, let's provide an example for my original question.

A dishwasher is installed in a cabinet, on the floor, with a counter top above it.
"If" one were to replace the wooden floor with a steel grate type screen would a majority of the sound created by the dishwasher go down instead of trying to penetrate the cabinet walls and the counter top? In effect making the ambient db levels lower?

Oh I get this idea of using a sound deadener on the cabinet walls and the underside of the counter top plus using additional sound deadening insulation around the dishwasher but could the noise levels be further reduced by providing the noise generated to go downwards into the basement?
To some degree, yes. If you're not reflecting the sound energy off the floor and back up into the living space, then it's going through the grate and being absorbed into the basement area below. It won't completely eliminate the sound of the dishwasher because not 100% of that sound is being reflected by the floor, but the portion that is (maybe 20%?) would be gone.

Looking at it a slightly different way, the sound from the dishwasher is going out six different ways (top, bottom, front, back, left and right). If you assume that it's all going out equally in all those directions, then letting just the sound going out the bottom and having it "disappear" would only eliminate about 15% of the total problem.
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Old 03-14-2019, 09:14 AM
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Originally Posted by km1125 View Post
To some degree, yes. If you're not reflecting the sound energy off the floor and back up into the living space, then it's going through the grate and being absorbed into the basement area below. It won't completely eliminate the sound of the dishwasher because not 100% of that sound is being reflected by the floor, but the portion that is (maybe 20%?) would be gone.

Looking at it a slightly different way, the sound from the dishwasher is going out six different ways (top, bottom, front, back, left and right). If you assume that it's all going out equally in all those directions, then letting just the sound going out the bottom and having it "disappear" would only eliminate about 15% of the total problem.
Hmmm, well doesn't that make sense.

Rough numbers only: 1/6th of the sound is eliminated by installing a grate floor = roughly 17%. 17% of 39 db is roughly 6.5 db. 32.5db for a dishwasher would be super incredibly quite. Heck my Bruel & Kjaer wouldn't even register that - 34 to 130 db(A). In addition to that reduction if I add the sound deadener to the three walls and underside of the counter top I could possibly get that 32.5 db(A) lower than 30 db(A) in the kitchen.

Sounds like a plan.
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Old 03-14-2019, 09:30 AM
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Originally Posted by Garett View Post
Hmmm, well doesn't that make sense.

Rough numbers only: 1/6th of the sound is eliminated by installing a grate floor = roughly 17%. 17% of 39 db is roughly 6.5 db. 32.5db for a dishwasher would be super incredibly quite. Heck my Bruel & Kjaer wouldn't even register that - 34 to 130 db(A). In addition to that reduction if I add the sound deadener to the three walls and underside of the counter top I could possibly get that 32.5 db(A) lower than 30 db(A) in the kitchen.

Sounds like a plan.
Realize the decibel scale is not linear it is logarithmic. 110 dB is twice as loud as 104 dB.
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Old 03-14-2019, 09:30 AM
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ear plugs
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Old 03-14-2019, 10:03 AM
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Buy a Bosch dishwasher ...ZERO NOISE DURING OPERATION! Case Closed
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Old 03-14-2019, 10:43 AM
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Originally Posted by MSChE View Post
Realize the decibel scale is not linear it is logarithmic. 110 dB is twice as loud as 104 dB.
Exactly.

17% might be like reducing it from 39 to 38 dB

Also, the noise doesn't really emanate equally from all sides.

You also need to consider how much is transmitted mechanically to either the cabinets, countertop or floor and then re-radiated as sound. Those vibrations could be more of an issue than the actual sound coming directly from the device. Making sure those contact points are isolated can make a huge difference. If the case is screwed to or touching the cabinet sides, for instance, then you're going to be transmitting sound. Even a small insulator (rubber or foam) will help eliminate most of that. Same goes with the feet. They are usually steel posts with hard plastic pads. A little rubber pad there too could make a difference.
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Old 03-14-2019, 10:49 AM
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How sound propagates is also frequency dependent. Low frequency waves passing thru barriers have very long periods and can retain a lot of power over distance versus high frequencies. Boom cars anyone?
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Old 03-14-2019, 05:52 PM
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Originally Posted by TUNEE View Post
Buy a Bosch dishwasher ...ZERO NOISE DURING OPERATION! Case Closed

Heard they don't do this










































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