9

I can think of a few possible ways to approach this. Probably the first thing to look at is the design of the case itself. They generally tend to be made up of thin, flat panels riveted to a frame. In this sort of situation you can get a lot of benefit from the use of a relatively small amount of sound deadening material. This approach is widely used on ...


9

Something like this? http://www.browninnovations.com/sound-dome/single-localizer-sound-dome As others have said, it is a speaker with a parabolic reflector to direct the sound down at the listener. You can make your own fairly easily: http://www.instructables.com/id/umbrelAudio-Sound-Dome-Umbrella/


8

With a description as vague as that, it was probably a parabolic reflector with a speaker at its focus. Pointed straight down, the "beam" of acoustic energy would be reflected from the floor right back into the "bell", with remarkably little leakage out the sides. A reflector with a diameter of 4-5 feet would be directional for frequencies down in the ...


7

The wavelength of sound at 40Hz is about 28 feet. However tall the wall is, the sound will diffract over the top of it and spread downwards on the far side. If you made the wall about 5 wavelengths high, it would be fairly effective. But I don't think your building regulations will let you build a 140 foot high wall, even if you can afford to do it! The bass ...


5

Ultrasound partially reflects when it encounters a medium with different acoustic impedance. It behaves like light and obeys Fresnel equations. If the angle of incidence is smaller than the total internal reflection angle, then part of the ultrasound beam will go forward (with some refraction) and part will reflect back from the interface between the media....


4

If I am understanding your question correctly you want to surround your room a vacuum so sound waves will not travel through your glass walls. In theory this would work very well but there are some major obstacles to overcome. Say your room is quite small, $12$ by $12$ by $8$. From the standpoint of a vacuum, earths atmosphere is at $14.7$ psi. $12$ feet ...


3

For fans used to move air, their primary noise radiation frequency will be (number of blades) x (revs per second of the fan shaft) and will be emitted in all directions if the fan shaft is vertical, as in most heatpump units. A 3-blade fan running at 1750 RPM will produce a hum at 88Hz. This will have a wavelength of about 11 feet and will diffract strongly ...


3

It will help to shield you from direct high pitch noise waves. because these waves short wavelengths will be blocked by objects in the range of your partition size. Say a noise of frequency of 500-hertz has a wave length (Lambda) of 340/500 = 68cm, but at 170-hertz lambda = 200cm. And much of the noise generated by the heat pumps will go around or be ...


2

Use a ballistics dummy. Ballistics dummies are designed and constructed to approximate the mechanical properties of the human body. They consist primarily of a molded ballistics gel designed for the same purpose. They are used most commonly for ballistics testing done by forensics and crime labs. Ballistics Dummy


2

It's not clear what you are asking. Noise cancelling headphones measure the noise to be cancelled, then actively produce the negative of that noise at just the right volume so that the two cancel. There is no issue of "recording" anything here. The microphone data is used real time, with perhaps a tiny delay to account for the propagation of the waves it ...


2

The first couple of things that come to mind are metallic 'wools' (ex. steel wool/stainless steel 'scrub pads'), or carbon foams. Metal wools will provide minimal thermal insulation (metal strands conduct, air gaps insulate, so it balances out mostly), but a large amount of vibration dampening 'limp mass.' Carbon foams/aerogels/what not: aerogels are very ...


2

Because the file is compressed. The sample rate and bits per sample are parameters of playback after decompression. The file size is for the compressed format, the amount of data that needs to be downloaded, not the amount of data that reaches the digital-to-analog converter.


2

Short frequency noise will tend to go around and even through objects, soil, or foundations to your home, as base humming sound. For 40 hertz or wavelengths of 5-10 meter object of the sizes of the same order are transparent. A lot of bass noise travels through foundation. Sound absorbing panels may be more effective.


2

You may try to build something like highway sound barrier. They say that modified acrylic sheet is the best material for this, and I guess it's cheap. Other option is not to build wall, but to insulate your house, using cork. Cork panels work very well for sound insulation. Especially if you manage to get egg crate shape, though it can be expensive depending ...


2

You could make a water drain trap. Drill a vertical hole that meets the microphone hole somewhere along its length, with a drain hole sloping down for the water to escape. You could then make a step change in diameter in the mike hole (for example between the pink and blue parts in our drawing) to stop the water getting past the drain. Since you appear to ...


1

Why have the hole perpendicular to the front surface? Angle the hole so that it is slightly uphill when the screen is at the angle as shown. Or, could you fit a membrane on the surface of the microphone and mount it closer to the front face with a larger hole for the entry rhs but smaller hole on the face lhs.


1

Springs and dampers are the classic method to reduce vibration, but don't expect the solution to be easy. Vibrations is a 4000 level ME course. If the problem is just the floor, then hanging the bed is probably the easiest option. I would recommend 4 ropes or chains anchored into the ceiling joists above the bed.


1

Its more the noise of the entire floor resonating with your jogging rhythm and vibrating as an echobox. Even if you manage to soften half of the impact by a clever system of plywood and foam you delay the resonance by just a few steps. Ideally you would need your treadmill in an enclosure on an expensive suspensions system.


1

A number of years ago I was in a similar situation. As kamran says, the entire building is involved. Before going further, I would point out that whether or not you are able to ignore it / whether you even care, is in significant part a product of your own stress level, possibly to do with the actual source of the disturbance, possibly unrelated. Current ...


1

I would try the cheapest way first - sleep on the stacked up mattresses without frame, nor box spring, to increase the effect of damping. A thick wall to wall carpet underneath will provide extra help to block out the noise.


1

Here is an antivibration mount which will probably work, and is cheap: Get you four small inner tubes (as used in wheelbarrows or small garden wagons, hand trucks, etc. and inflate them about half-full of air. Cut you four squares of plywood to the same size as the inner tubes and place one square atop each of the tubes. Lift your bedframe up off the floor ...


1

Apart from the other two valid options (rubber pads and anti-vibration mounts) another (maybe less expensive) option would be to increase the mass which is attached on the bed. effectively you would be creating option (c) in the above diagram. Increasing the mass, (in a simplified model) would decrease the eigenfrequency $\omega_n$. Therefore, (assuming ...


1

I would say it's the entire building, including your ceiling and even the foundation of the building that is vibrating. I have seen even the sidewalk shaking. Remedies can be very elaborate and costly with just a slight improvement. I would try something like this floor barrier in combination with earplugs and maybe eye blinds with rubber pads under your bed ...


1

It's difficult to say what will work in your situation. I think some trial and error might be involved. Constructing a frame and hanging the bed as you suggest could work but I would vibration dampers under each leg of the frame and if possible in each of the hanging ropes. It seems a lot of work though. It might be easier to put some vibration dampers under ...


1

Yes, it is definitely going to impede the circulation of air. The fan of the HVAC blows the air very gently, so much so that for a large room one register maybe not enough. For blocking the light you could try hanging a small drape 12 inches in front of the grill. If the noise is really a nuisance the only effective solution is to connect your grill ...


1

Some large buildings have a transformer attached to them for the mains supply for all apartments. The vibrations are probably being transmitted via harmonic resonance due to acoustic amplification. This may have been why previous owners sold the property. Human body operates at 25Hz which means harmonic octave frequencies are more noticeable to us. It may ...


1

Currently, honeycomb cores are sometimes faced with an adhesive film between the Prepreg skin and the core. But you seem to be describing a viscoelastic midlayer. This arrangement could be simulated parametrically with FEA and the polymer’s FEA Support Test Data. (Parametric FEA model: adjusting thickness and surrounding core/facesheet assembly material ...


1

If the hard disk drive was replaced by with a solid state drive and the heat sink for the CPU chip was made bigger and externalized it would be possible to have a silent computer which cooled directly to the atmosphere or could be cooled by other means. Currently, a heat sink is attached to a CPU chip and all this is contained within the computer case, ...


1

Since nearly all the sound (aside from speakers themselves) originates in cooling fans, it's going to be really tough to block sound while allowing exhaust airflow. You'll need a different, expensive, cooling system. Probably the next noisiest is the hard drive, which if well heat-sunk could be covered locally with sound-absorbing material (or switch to all-...


1

To dampen vibrations the easy way, you need lots of mass and some kind elastomer/damper to convert vibrations to heat. One way of making this as a single piece would be casting a soft elastomer in a mold filled with lead shot.


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