Q.29 : causes of noise and ways of reducing noise in

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Q.29 : causes of noise and ways of reducing noise in

In general it is associated with something unwanted. It could be acoustic noise — background noise. In electronic terms it will generally be an unwanted electrical signal. That may be random or systematic. Either way, it would be a nuisance if the level is high enough to affect the characteristics or measurement of a signal sufficiently. The method of preventing it depends on which type of noise it is.

Radiated noise is noise that ends up in your circuitry from somewhere else through the air or even in a vacuum if that is your normal working environment. Preventing it affecting your circuitry could be by screening. The use of ground planes on PCBs can help reduce the susceptibility of circuitry to interference in a similar way to screening.

Even without enclosing a circuit board a close ground plane helps reduce the pickup of radiated interference in sensitive, high impedance parts of a circuit. Conducted noise can be similar to radiated noise i. This could be along a power cable, either high or low voltage, AC or DC.

It could be connections to buttons, displays or other parts of the system not on the PCB. Conducted noise could have started as radiated noise and then is picked up on wires in the system acting as an antenna and then becomes conducted noise. Minimising the effect of conducted noise is different to radiated noise. Conducted noise is usually best reduced by adding filtering to the cables where the noise is entering the system.

This could be filtering by adding ferrite clamps to increase the inductance of a cable — the familiar lumps on power supply cables, USB cables etc. The filtering has to reduce the noise while minimising the detrimental effects on the desired signal. Techniques such as twisted wire pairs and differential signaling such as LVDS can make circuitry tolerant of conducted noise without actually reducing the noise. A spectrum analyser or oscilloscope with fast fourier transform FFT capability can be very helpful in tracking down where noise is coming from by helping to show the nature of the noise and identify specific frequencies which may not be obvious otherwise.When gears work, especially at high loads and speeds, the noise and vibration caused by the rotation of the gears is considered a big problem.

However, since noise problems tend to happen due to several causes in combination, it is very difficult to identify the cause. The following are ways to reduce noise and these points should be considered in the design stage of gear systems. When it comes to a high power and high-speed gears such the ones that transmit power of a motor or engine, the gear noise or vibration often becomes a problem.

However, the countermeasure for the noise is not easy since the gear noise usually occurs from multiple various factors. In this part, examples of gear noise and countermeasures are explained. The gear noise can be divided broadly into two, depending on where the noise occurs.

First is the one that occurs from the gear itself, and second is from peripheral components such as gearboxes. When noise is from the gear itself, it can be from the friction when teeth mesh.

q.29 : causes of noise and ways of reducing noise in

Though it depends on the conditions such as the number of rotation, the frequency of sound is relatively low for the most cases. In this kind of case, first thing to check is the accuracy of a gear. Also, even when the accuracy of a gear was high and shape was theoretically correct, the tooth bearing could be uneven when a gear shaft is warped from the pressure on a gear.

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In this kind of situation, the noise can be reduced by adjusting the tooth bearing with improvement of the rigidity of a shaft or treatment like crowning. The smooth meshing of teeth can be an important factor to limit noise and vibration from a gear.

q.29 : causes of noise and ways of reducing noise in

The countermeasures are using profile shifted gears to prevent interference and having a reasonable backlash, lubricating a gear, and making the tooth flank smooth by reducing the roughness of it. Particularly for the smoothness of a tooth flank, plastic gears are highly effective, but one needs to be careful because it is sensitive to the humidity and temperature compared to metal gears.

Among peripheral components of a gear, a gearbox is often the cause of noise. In many cases, noise occurs when vibration from a gear transmits to a gearbox, making it vibrate sympathetically. The frequency of sound is most likely to be high compared to the noise from the friction of teeth.

For the countermeasures, one can improve the rigidity of a gearbox or use cast iron that has high vibration damping factor for a gear, gear boss, and gearbox. Other effective methods are enhancing the front gear contact ratio by reducing the reduction ratio of a gear and improving the overlapping meshing ratio with a helical gear.

q.29 : causes of noise and ways of reducing noise in

The countermeasures for the noise from a gear are also effective as it is caused by vibration from a gear. Use High-Precision Gears Reduce the pitch error, tooth profile error, runout error and lead error.

Grind teeth to improve the accuracy as well as the surface finish. Use a Better Surface Finish on Gears Grinding, lapping and honing the tooth surface, or running in gears in oil for a period of time can also improve the smoothness of tooth surface and reduce the noise. Ensure a Correct Tooth Contact Crowning and end relief can prevent edge contact. Proper tooth profile modification is also effective. Eliminate impact on tooth surface.

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Have a Proper Amount of Backlash A smaller backlash will help produce a pulsating transmission. A bigger backlash, in general, causes less problems.January 17, References Approved.

To create this article, 62 people, some anonymous, worked to edit and improve it over time. This article has 25 testimonials from our readers, earning it our reader-approved status. This article has been viewedtimes. Learn more Noise pollution isn't just annoying: it can cause deafness, fatigue, and even psychological problems.

If you want to cut back on the noise pollution in your life, work on eliminating loud sounds made by machines both inside and outside your house. If necessary, sound-proof your home so you can get some peace and quiet.

Taking measures to prevent noise pollution will help you and your family feel happier and healthier. If you want to cut down on noise pollution in your life, work on eliminating sounds made by machines inside and outside of your house. If there are any other sources of constant noise, try to keep them as far from your sleeping and living areas as possible. You can also try earplugs or noise-canceling headphones to get a little peace and quiet, no matter where you are.

Go for a walk in a quiet natural spot or sit in a library for a while. Stay there and enjoy the silence for a few hours or until you feel renewed and ready to reenter the noise of daily life. To learn how to install noise-reducing insulation and glass, keep reading! Did this summary help you? Yes No. Rupankar Bhattacharjee. Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker.

Log in Facebook. No account yet? Create an account. Edit this Article. We use cookies to make wikiHow great. By using our site, you agree to our cookie policy. Learn why people trust wikiHow. Explore this Article methods. Tips and Warnings. Related Articles. Article Summary. Co-authored by 62 contributors Community of editors, researchers, and specialists January 17, References Approved. Method 1 of Sound-proof your space.

When you can't stop the noise at its source, you can do your best to keep it out. Sound-proofing your home will help you rest easier at night and keep your home quieter during the day as well. If you can't sound-proof your entire home, you might want to invest in sound-proofing your bedroom, so you'll have at least one respite from the noise when you just can't take it anymore.

Noise (electronics)

If you don't want to reconstruct your walls and floors with sound-proof building materials, consider the less expensive option of installing carpeting and wall coverings that soften and absorb sounds. Acoustic foam panels are a cheap, easy-to-install option when you want to quickly soundproof a room.Whether you're using a running machine, lifting weights, rowing or doing burpees all of these movements create a significant amount of impact sound.

If you are setting up a home gym or you run a gym that is in conveniently located in the same building as residential homes then it is important to ensure that excessive noise doesn't create problems with your neighbours or family If you have a solid concrete floor none of that energy is absorbed so a huge impact is created over a short duration which creates a very big noise.

Machines such as running machines can also create a lot of noise due to the impact of feet repeatedly hitting it. Dropped weights and noisy machines can combine to create a very noisy atmosphere unless gym soundproofing measures are put in place.

Reducing the noise levels in your gym is always going to be beneficial, it makes the gym more comfortable for members to work out in, it prevents neighbours from being disturbed and it can also help your equipment last longer. Getting the correct flooring in your gym is the number one step you should take to minimise gym noise.

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Flooring does incredible things for gym sound reduction. Rubber flooring means that when a weight is dropped it doesn't immediately stop, instead the flooring gives, this means that the falling speed of the weight doesn't immediately fall to zero, instead it stops more gradually. This means that the noise generated is greatly reduced, instead of creating a high impact sound over a short duration rubber flooring increases the duration of the sound meaning that noises will be lower frequency.

This significantly reduces the volume as the energy is dispersed over a longer time frame into the flooring. Decoupling noisy equipment from the floor will help absorb impact vibrations and stop them travelling through your floor.

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An effective way of decoupling is to fit shock absorbing pads to the feet of all of your exercise machines. Fitting these to treadmills will help further cushion the impact and reduce the amount of sound generated when someone is running on it. Machines such as stationary bikes and rowing machines usually make much less noise than a treadmill however if you do feel the need to dampen their vibrations then you put them on top of an anti-vibration treadmill mats the kind which is typically used under washing machines.

Bumper plates are weights which are designed to be dropped. Bumper plates are much thicker than cast iron plates, this is because they are made from solid rubber which surrounds a steel or brass hub as seen in the photo above. Being made of rubber means they can be dropped from overhead and will bounce, causing no damage to the floor and significantly reducing the volume of impact sound.

Equipping your gym with bumper plates will help reduce the impact of sound vibrations caused by dropped weights. You should make bumper plates available in any part of the gym where people perform exercises where the barbell is likely to be dropped, for example:.

Weightlifting platforms encourage gym users to lift heavy weights in areas which are designed specifically to reduce the impact of big weights being dropped. A weightlifting platform consists of a central wooden platform where the lifter stands while making their lift.

Either side of this are thick rubber mats, usually at least a couple of inches thick considerably thicker than most gym flooring. When a heavy barbell is dropped onto the rubber mats they absorb a lot more of the impact than a standard rubber floor would because they are so much thicker.

A professionally built lifting platform can be very expensive, if you can't afford the expense it is not too difficult or expensive to build one yourself. Big gym halls can often feel very echoey, this has the undesirable effect of seemingly amplifying all sounds within the gym.This page requires that javascript be enabled for some elements to function correctly. Noise, or unwanted sound, is one of the most common occupational hazards in American workplaces. Exposure to high levels of noise may cause hearing loss, create physical and psychological stress, reduce productivity, interfere with communication, and contribute to accidents and injuries by making it difficult to hear warning signals.

The content is based on currently available research publications, OSHA standards, and consensus standards. The chapter is divided into six main sections. Following this introduction, the second section provides background information about noise and noise regulations and an overview of noise controls. The third section describes worksite noise evaluations, including noise measurement equipment, noise evaluation procedures, and noise sampling.

The fourth section offers investigative guidelines including methods for planning the investigation and outlines a strategy for conducting noise evaluations. The fifth section describes noise hazard abatement and control, including engineering and administrative controls, hearing protection, noise conservation programs, cost comparisons between noise hazard abatement options, and case studies. The final two sections provide references used to produce this chapter and resources for obtaining additional information.

Following the main sections, the appendices provide a glossary of terms, sample calculations, and expanded discussion of certain topics introduced in the chapter. A textbook definition of sound is "a rapid variation of atmospheric pressure caused by some disturbance of the air.

Why is reducing noise pollution crucial for aviation?

Sound can travel through any elastic medium e. The vibrations are converted into mechanical energy by the middle ear, subsequently moving microscopic hairs in the inner ear, which in turn convert the sound waves into nerve impulses. If the vibrations are too intense, over time these microscopic hairs can be damaged, causing hearing loss.

Noise is unwanted sound. In the workplace, sound that is intense enough to damage hearing is unwanted and, therefore, is considered to be noise. Several key terms describe the qualities of sound.

q.29 : causes of noise and ways of reducing noise in

These qualities influence how it affects hearing and health, how it is measured, and how it can be controlled. Effective occupational noise investigations require the investigator to understand these basic terms. The wavelength of sound is usually measured in meters or feet. Wavelength is important for designing engineering controls. For example, a sound-absorbing material will perform most effectively if its thickness is at least one-quarter the wavelength.

Frequency, f, is a measure of the number of vibrations i. It is measured in hertz Hzwhere one Hz is equal to one cycle per second. Sound frequency is perceived as pitch i. The frequency range sensed by the ear varies considerably among individuals. A young person with normal hearing can hear frequencies between approximately 20 Hz and 20, Hz.

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As a person gets older, the highest frequency that he or she can detect tends to decrease. Human speech frequencies are in the range of Hz to 4, Hz. This is significant because hearing loss in this range will interfere with conversational speech.

The portions of the ear that detect frequencies between 3, Hz and 4, Hz are the earliest to be affected by exposure to noise. Audiograms often display a 4,Hz "Notch" in patients who are developing the beginning stages of sensorineural hearing loss.

The speed at which sound travels, c, is determined primarily by the density and the compressibility of the medium through which it is traveling.In electronics, noise is an unwanted disturbance in an electrical signal. In communication systemsnoise is an error or undesired random disturbance of a useful information signal. The noise is a summation of unwanted or disturbing energy from natural and sometimes man-made sources. Noise is, however, typically distinguished from interference[a] for example in the signal-to-noise ratio SNRsignal-to-interference ratio SIR and signal-to-noise plus interference ratio SNIR measures.

While noise is generally unwanted, it can serve a useful purpose in some applications, such as random number generation or dither. Different types of noise are generated by different devices and different processes. Johnson—Nyquist noise [1] more often thermal noise is unavoidable, and generated by the random thermal motion of charge carriers usually electronsinside an electrical conductorwhich happens regardless of any applied voltage.

Thermal noise is approximately whitemeaning that its power spectral density is nearly equal throughout the frequency spectrum. The amplitude of the signal has very nearly a Gaussian probability density function.

A communication system affected by thermal noise is often modelled as an additive white Gaussian noise AWGN channel. Shot noise in electronic devices results from unavoidable random statistical fluctuations of the electric current when the charge carriers such as electrons traverse a gap. If electrons flow across a barrier, then they have discrete arrival times.

Those discrete arrivals exhibit shot noise. Typically, the barrier in a diode is used. The flow of rain may be relatively constant, but the individual raindrops arrive discretely. The root-mean-square value of the shot noise current i n is given by the Schottky formula.

The Schottky formula assumes independent arrivals. Vacuum tubes exhibit shot noise because the electrons randomly leave the cathode and arrive at the anode plate. A tube may not exhibit the full shot noise effect: the presence of a space charge tends to smooth out the arrival times and thus reduce the randomness of the current. Pentodes and screen-grid tetrodes exhibit more noise than triodes because the cathode current splits randomly between the screen grid and the anode.

Conductors and resistors typically do not exhibit shot noise because the electrons thermalize and move diffusively within the material; the electrons do not have discrete arrival times.

Shot noise has been demonstrated in mesoscopic resistors when the size of the resistive element becomes shorter than the electron—phonon scattering length. It occurs in almost all electronic devices and results from a variety of effects.

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Burst noise consists of sudden step-like transitions between two or more discrete voltage or current levels, as high as several hundred microvoltsat random and unpredictable times. Each shift in offset voltage or current lasts for several milliseconds to seconds. It is also known a popcorn noise for the popping or crackling sounds it produces in audio circuits.

If the time taken by the electrons to travel from emitter to collector in a transistor becomes comparable to the period of the signal being amplified, that is, at frequencies above VHF and beyond, the transit-time effect takes place and noise input impedance of the transistor decreases. From the frequency at which this effect becomes significant, it increases with frequency and quickly dominates other sources of noise. While noise may be generated in the electronic circuit itself, additional noise energy can be coupled into a circuit from the external environment, by inductive coupling or capacitive couplingor through the antenna of a radio receiver.

In many cases noise found on a signal in a circuit is unwanted. There are many different noise reduction techniques that can reduce the noise picked up by a circuit. Noise may also be characterized by its probability distribution and noise spectral density N 0 f in watts per hertz.

Sources, Causes, and Ways to Decrease Process Noise Levels

A noise signal is typically considered as a linear addition to a useful information signal. Noise is a random process, characterized by stochastic properties such as its variancedistributionand spectral density. Integrated circuit devices, such as operational amplifiers commonly quote equivalent input noise level in these terms at room temperature. Noise power is measured in watts or decibels dB relative to a standard power, usually indicated by adding a suffix after dB. Telecommunication systems strive to increase the ratio of signal level to noise level in order to effectively transfer data.

Noise in telecommunication systems is a product of both internal and external sources to the system.Sep 10, Aviation 0 comments. According to a report by the Federal Aviation Administration of the U. Identical study tested sound levels on 2 airbus A flights and the average noise levels in-flight were between dB Aslightly below the 90dB threshold, however way above the human annoyance sound level of 65 dB A.

Furthermore, studies like the one by The University of New South Wales UNSW Sydney have shown that continuous exposure to noise can reduce the recognition of memory and cause a person to be additionally fatigued. A recent example of how fatigue can cause problems inside the cockpit is Air Canada Flight On average, it emits Newer aircraft are even under stricter noise restrictions and manufacturers have to comply with Chapter fourteen regulations released in As a result, newer aircraft like the Airbus Aneo emits As a result, easyJet was forced to pay nightly fees for the flight.

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It is mandatory to procure user consent prior to running these cookies on your website. Why is reducing noise pollution crucial for aviation? Why is reducing aircraft noise pollution important? Studies and Researches Furthermore, studies like the one by The University of New South Wales UNSW Sydney have shown that continuous exposure to noise can reduce the recognition of memory and cause a person to be additionally fatigued. Source www.


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