Solving Noise Problems: All You Need to Know

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In summary, the conversation discusses various aspects of noise, including the relationship between sound power level and sound pressure level, the different noise parameters and their correlation to noise fluctuation and annoyance, the effectiveness of balconies and barriers/enclosures in noise mitigation, and the impact of construction and traffic noise. It also touches on the physics of sound generation and detection by the human ear. The conversation highlights the importance of understanding the specific conditions and variables in order to effectively reduce noise levels.
  • #1
ben9108
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Dear Sir or Madam

I have some troubles regarding the noise subject. Would you mind to help me solving the following problems? Thank You.

1. Under what condition will sound power level be lower than sound pressure level?
2. L10, Leq, Lmax ~ How are they related to noise fluctuation and annoyance to people
3. Why L10 cannot be used to assess night-time traffic noise?
4. What is the relationship between L10, Leq, Lmax, for the noise from traffic, industrial fans, and piling machine?
5. How to the parameters L10, Leq, L90, Lmin, Lmax, L10 – L90 and Lmax – Lmin change with traffic noise in the day and night time? Which of these parameters can be closely correlated to annoyance of people?
6. Why balconies can be a more effective noise mitigation than barriers/ enclosures?
7. Why the important of length, gaps, and absorptive material on the noise barrier performance?
8. What measures to reduce train and industrial noise?
9. Why the significance of low frequency noise from train and industrial machines?
10. How acoustic wave from human speech is generated, propagated and detected by human ear?
11. Why shaking a metal plate with large hand movement cannot generate noise but scratching it with a screwdriver can radiate loud noise?
12. Why rows of trees 5m high and 20m wide may not block or absorb the noise but may increase the noise instead?
13. What are the dominant frequencies of the noise emanating from electric motor unit, light rail, and locomotive? If the train noise level is 55dB(A) and 85 dB(C), which is the major noise source?
14. Why enclosure is needed in rail when there are crossovers of rails? Do you think the floating slab can reduce the noise near crossovers?
15. Why absorptive barrier close to the rail and floating slab should be used to reduce train noise on the viaduet. Why the negative effects of these on the operation of the train?
16. Can the acoustic wave from the source of sound power level of 0dB be sensed by human ear?
17. Why the noise impact from construction in terms of L10, Lmax, Leq and the period and duration when compared with industrial and traffic noise?
18. Why barrier or enclosure may not be effective to reduce construction noise by evaluating the major noise sources?
19. Why road resurfacing and barriers cannot reduce traffic noise near road junctions?
20. Why Low frequency noise impact can be higher than high frequency noise impact?

Cheers

Ben
 
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  • #2
ben9108 said:
11. Why shaking a metal plate with large hand movement cannot generate noise

Why do you think this makes no noise?
If the metal plate flexes it makes a lot of noise.
Even if it doesn't flex there is edge cavitation that makes a woosh noise.
Then there are the sub audible frequencies generated, still noise.
 
  • #3
Have any idea for the other questions
 
  • #4
ben9108 said:
Have any idea for the other questions
Just commenting on something that appears wrong.

Show us what you worked out.
Ask a specific question about what you think isn't working in your solution.
Nobody is going to do your homework for you.
 
  • #5
Ben,
I see this is your first time here. If you read the guidelines that you agreed to you will notice that we do not do your homework problems for you. If you wish to take one problem at a time and show us the work you have put forth trying to solve it, we will help.

In regards to the number 11 that has already been brought up, a plate (an infinite plate) can be a poor radiator of sound if a couple of conditions are met. If the frequency of the bending wave in the plate is greater than what is known as the coincidence frequency (or critical frequency) then the bending wavelength and wave speed are greater than the wavelength and wave speed in the acoustic medium (i.e. air) and the plate radiates sound. If it is below the coincidence frequency then, if you go through the math, it turns out that the sound radiation has a very rapid exponential decay factor and thus does not radiate sound very well. Of course, that is with an infinite plate. A finite plate will have some sound radiation due to boundary conditions, but that can be very little.
 

1. What is considered a "noise problem"?

A noise problem is any unwanted or excessive sound that interferes with daily activities or causes discomfort, annoyance, or harm to individuals. This can include loud music, construction noise, traffic noise, or even noise from appliances.

2. How can I determine the source of a noise problem?

The first step in solving a noise problem is to determine the source of the noise. This can be done by conducting a noise survey, which involves measuring the sound levels at different locations and times. Additionally, talking to neighbors or using sound mapping technology can also help identify the source of the noise.

3. What are some methods for reducing noise?

There are several methods for reducing noise, depending on the source and severity of the problem. Some common solutions include soundproofing walls, installing double-pane windows, using sound-absorbing materials, and creating barriers between the source of the noise and the affected area. In some cases, addressing the source of the noise directly, such as fixing a noisy appliance or muffling a loud engine, can also help reduce noise levels.

4. Are there any regulations for noise control?

Yes, many cities and municipalities have noise ordinances in place to regulate noise levels. These ordinances typically specify acceptable noise levels for different times of day and types of areas (e.g. residential, commercial, industrial). It is important to research and adhere to these regulations when attempting to solve a noise problem.

5. Can noise problems have a negative impact on health?

Yes, prolonged exposure to excessive noise levels can have negative effects on health, including hearing damage, sleep disturbance, and stress-related issues. It is important to address noise problems promptly to prevent potential health risks.

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