The Ultimate Buyer's Guide for Purchasing Buy Noise Barrier

09 Apr.,2024

 

Understanding Noise

 

Sound & Sound frequency

A sound is a vibration of air, a variation in air pressure, that makes the membrane of the ear vibrate thus becoming "audible". Different types of sounds can be defined by measuring the frequency of sound waves per second in the unit Hertz (Hz):

  • Higher sounds have a higher frequency of vibrations per second.
  • Lower sounds have a lower frequency of vibrations per second.

The human ear can only perceive and "hear" those sound waves if their frequency lies between 20 Hz (20 vibrations per second) and 2000 Hz (20,000 vibrations per second).

 

 

Sound loudness

The loudness of sounds can be defined by measuring their intensity in the unit Decibel (dB):

  • Louder sounds have a higher intensity.
  • Quieter sounds have a lower intensity.

It is worth noting that Decibel are expressed on a logarithmic scale, which makes explaining changes in loudness a little complicated. For instance, a reduction of 7dB means that the sound intensity has been divided by 4. An augmentation by a factor of 1000 corresponds to a 30 dB change in level.

 

 

What is noise?

A noise is as an unpleasant, disturbing sound. The perception of a sound can vary from one person to another, but louder sounds are generally considered noise, especially when they have higher frequencies.

How can noise levels be measured?

The unit used in acoustics to define and measure sound intensity is Decibel (dB). Decibel uses a logarithmic scale which works very differently from a linear scale. Human perception of loudness is not linear, so a logarithmic scale is well suited to express our experience of sound. In fact, when the human ear receives a sound stimulus it tries to amplify very weak sounds and to attenuate very strong sounds.

So calculating the Decibel is based on the comparison between the input signal and the output signal. A linear scale as used on a ruler, where a distance of 30 inches is three times as long as a distance of 10 inches, couldn't adequately express a decrease or increase in sound intensity.

When using a logarithmic scale to measure noise levels, adding 3 dB means multiplying the loudness by two. If we divide the intensity of a sound by 2, the sound level only drops by 3 dB.

EXAMPLE : Using 2 vacuum cleaners simultaneously in one room doesn't double the decibel level, but only increases it by 3 dB. To put it simple: 70 dB plus 70 dB doesn't equal 140 dB, but only 73 dB. Following this rule, 4 vacuum cleaners will create a sound level of 76 dB.

If we measure noise on a scale from 0 to 130 Decibels: 0 dB represents the threshold of audibility, 130 dB represents the threshold of pain. Most of the sounds of everyday life are between 30 and 90 dB. 

 

Decibel levels for everyday noises:

Sound                                              Decibel level  Breathing 10 dB Rustling leaves 20 dB Whisper 30 dB Quiet conversation 40 dB Light trafic at close range 50 dB Normal conversation 60 dB Vacuum cleaner 70 dB Loud traffic noise at close range 80 dB Headphones at full volume 90 dB Club 100 dB Car speakers at full volume 110 dB Air plane take-off, jackhammer 120 dB Rock concert 130 dB



What is the increase in sound intensity between two different Decibel levels ? 

Sound intensity is the energy needed to produce a given level of sound and not to be confused with sound volume which is the level at which we perceive the resulting sound.The mathematical relationship between Decibel (dB) and sound intensity works as follows: each 10 dB increase results in a 10-fold increase in sound intensity which we perceive as a 2-fold increase in sound volume. Thus, from 0 dB to 10 dB there is a 10-fold increase in sound intensity, just as there is from 10 dB to 20 dB or from 34 dB to 44 dB. 


Decibel levels for everyday noises VS. increase in sound intensity and perceived volume:

Sound                                          

Decibel level 

Increase in sound intensity                 

Increase in perceived volume 

 

0 dB

 

 

Breathing

10 dB

10 times the sound intensity

2 times as loud

Rustling leaves

20 dB

100 times the sound intensity

4 times as loud

Whisper

30 dB

1,000 times the sound intensity

8 times as loud

Quiet conversation

40 dB

10,000 times the sound intensity

16 times as loud

Light trafic at close range

50 dB

100,000 times the sound intensity

32 times as loud

Normal conversation

60 dB

1,000,000 times the sound intensity

64 times as loud

Vacuum cleaner

70 dB

10,000,000 times the sound intensity

128 times as loud

Loud traffic noise at close range

80 dB

100,000,000 times the sound intensity

256 times as loud

Headphones at full volume

90 dB

1,000,000,000 times the sound intensity

512 times as loud

Club

100 dB

10,000,000,000 times the sound intensity

1024 times as loud

Car speakers at full volume

110 dB

100,000,000,000 times the sound intensity

2048 times as loud

Air plane take-off, jackhammer

120 dB

1,000,000,000,000 times the sound intensity

4096 times as loud

Rock concert

130 dB

10,000,000,000,000 times the sound intensity    

8192 times as loud


Actual sound levels VS. noise perception

The intensity of a sound can be measured by using a microphone to convert the sound into power and then interpreting the power obtained in terms of Decibels (dB). However, this physical sound level does not really correspond to the perception of the sound that we are having.

 

Measuring human noise perception

The human ear does not perceive all the sound frequenciesin the same way: we are deaf to low-frequency sounds (below 20 Hz) and high-frequency sounds (above 20,000 Hz), and are most sensitive to sounds around 2000 Hz.This is why there are different versions of the "dB" scale which are decibel readings that have been adjusted to take into account the varying sensitivity of the human ear to different frequencies of sound:

  • dBA (A-weighted sound levels) - measurement of common sound intensities, using a filter to account for the loudness as perceived by a human ear (everyday noises).

  • dBC (C-weighted sound levels) - measurement of higher sound intensities, specifying the effect of peak and high impact sounds on the human ear (extreme loudness such as a live concert).

It is not possible to reproduce the behavior of the "average" human ear with a single filter (and even less that of the ears of each particular individual), but in most situations our hearing can be measued with the the dBA scale. This scale is a good starting point from which to measure sound perception, but gives us only an idea of the perceived noise levels. 

Factors impacting noise perception

In reality, the overall noise is composed by many different sound levels all across the frequency spectrum, which is why measuring the perception of sound is very complex and depends on a large number of factors:

  • Individual sensitivity (depending on age, culture, time of day...)

  • Spatial configuration (inside/outside, construction of the building, furniture in the room...)

  • Distance to the noise source (sensor position)

  • Sound frequency (low, medium, high)

  • Sound repeatability (continuous, intermittent, impulsive)

  • Temporal exposure (long-term, short-term)

These are the most common reasons that explain a difference between the actual sound and the perceived noise. The Decibel measurements can only give a limited representation of the perceived "reality", especially as the sensitivity to noise varies greatly from one individual to another. Some populations can be more vulnerable to noise exposure than others, such as students during an exam or people affected by hearing loss.

 

Types of noise

There are many different categories of noise, from natural to man-made. In big cities we are confronted with man-made sounds, often quite aggressive.

We try to find soundproof solutions to create a quieter environment and get rid of diffrent types of noise:

  • continuous noise (like machinery that runs without interruption, car traffic): is noise which remains constant and stable over a given time period

  • intermittent noise (trains, aircrafts, sirens): is noise which does not remain constant and stable over a given time period

  • impulsive / impact noise (gun shot): is a very short burst of loud noise which lasts for less than one second.

The noise we find the most disturbing and that we are the most exposed to (unless you live in the countryside) is traffic noise. Unfortunately, this is also the hardest type of noise to reduce, let alone cut out.

The best bet to dampen traffic noise is to combine different solutions: noise-reducing curtains, rugs, window frame insulation foam, etc. 

 

The difference between sound proofing and sound absorption

To understand the difference between sound absorbtion and sound proofing let's remember how the noise travels: when a sound wave is emitted, it is modified by parameters such as distance or obstacles. When a sound wave meets an obstacle like the wall of a room, a certain amount of energy is reflected back into the room. These successive reflections are called reverberation.

Sound proofing

Sound proofing (or sound insulation) attempts to stop noise by blocking the acoustic wave from traveling to adjacent spaces. 

Insulation can only be achieved with mass and/or multiple layers ot material in the walls or windows. It means, that the construction of the building is essential in this matter, and that additional sound proofing is not easy once the structure is already built.

 

Sound absorption

Sound absorption aims to reduce noise by limiting the reverberation of the sound wave within a space.

Absorption can be obtained with light materials (such as specific fabrics) that are applied to walls or windows, meaning it is easier to achieve once the structure is already built.

How can "soundproof" curtains help?

The impact of any sound insulation curtain depends on the kind of noise you are experiencing and the construction of your building.

As mentionned before, there are different types of noises with either high, medium or low frequencies. Different applications and treatments are needed to confront this spectrum of noises and there is no one-for-all solution.

Each sound environment is different and the intricacies of one's home have to be taken into account, because the noise does not come in simply from your windows but also seeps in through the walls and various openings.

Moondream sound insulation curtains aim to adress both - sound proofing and sound absorbtion - as best as possible with a solution that is equally functional and aesthetic. Our patented curtains have three strategically assembled layers of fabric to reduce the transmission of the sound wave and absorb the reverberation of the sound as well:

  • The incoming sound energy is dampended and divided by 4, reaching a drop of up to 7 decibels. 
  • The transmission of the sound wave is reduced and the reverberation is reduced: for a surface area of approximately 215 square feet, the reverberation time is reduced by 0.4 seconds.

The result of both actions is a quieter acoustic environment that will contribute significantly to your wellbeing. To improve the curtain's results you can add other absorbent materials to your floors such as carpet or a rug.

You have to be aware that if you wish to cut out certain low frequency sounds such as traffic noise completely, a curtain might not be enough (soundproof windows and thick walls would be necessary). Moondream curtains can however dampen the noise which can already be an important improvement and is a much more cost effective solution, especially if you are just renting.

Outdoor sound blankets are a great cost-efficient and highly effective way of reducing loud noises. These flexible quilted panels are extremely versatile, which is why they are so popular among construction companies.

If you are in the market for some outdoor sound-proofing these are a great option. However, outdoor sound blankets are not a one size fits all solution. There are a few different types of sound absorbing and blocking blankets; some will render better results than others. To help you out, we have put together a summary of what exactly outdoor sound blankets are, what features you should look for and where to buy them.

What are Outdoor Sound Blankets?

Outdoor sound blankets are large weather-resistant vinyl encapsulated panels that are engineered to absorb and block noise. These exterior sound panels are typically used to deafen the sound of large equipment, HVAC systems and construction projects. They are also great to help comply with local noise ordinances.

Outdoor sound blankets are popular because they are extremely durable, highly effective and cost-efficient. These panels can withstand intense wind, freezing temperatures, high heat and prolonged UV exposure. Additionally, the unique design of these flexible panels allows installation on nearly any support structure, such as fences or frames. Outdoor sound blankets are a permanent or temporary solution.

What to Look For

There are a few aspects of outdoor sound blankets to evaluate while deciding what type of barrier will be best for you. These include the NRC rating (Noise Reduction Coefficient), the STC rating (Sound Transmission Class) and the temperature range/weather resistance.

1. Noise Reduction Coefficient

There is a bit of science involved when shopping for sound blankets. The first term we will cover is the NRC. This rating measures the absorption of sound; the higher the rating, the better the product is at absorbing sound. The thickness and density are the two determining factors in calculating the NRC rating.

The NRC rating ranges from 0.0-1.0. For example, if an outdoor sound blanket has an NRC rating of .65 this means 65% of the sound in the space absorbed and the other 35% reflected back into space. While reviewing sound blankets, keep in mind the higher the NRC rating and the thicker the product the better.

2. Sound Transmission Class

In addition to reviewing the NRC of outdoor sound blankets, you should pay attention to the STC (Sound Transmission Class) rating. The STC rating also measures how much the product is able to reduce noise; but instead of measuring the amount of absorption, it measures the transmission loss (or how much sound will still come through the barrier).

STC ratings are found based on sound frequency measurements in Hertz (or Hz). To give a frame of reference, most humans are born with the ability to hear frequencies as low as 20 Hz and as high as 20,000 Hz. However, for standard sound testing purposes, the soundproofing industry measures barrier performance based on a range of 125 Hz to 4,000 Hz.

Generally speaking, the higher the STC rating the better. However, it is important to not solely rely on the STC rating as it can be misleading in certain soundproofing scenarios. For example, if you are wanting to deafen the sound of construction noise or heavy bass music, you should rely more heavily on the NRC rating. This is because noise sources such as traffic noise, heavy equipment, and bass drums are all below 125 Hz and will not be applicable to the STC rating since the scale starts at 125 Hz. For higher pitched frequencies, STC ratings are extremely reliable.

3. Temperature and Weather Resistance

The final most important aspect of an outdoor sound blanket you should take into consideration while purchasing is the weather durability. Considering these barriers will brace the natural elements at any given time of year, you will want to ensure they are capable of withstanding high heat in the summer, freezing temperatures in the winter and everything in between.

Keep in mind these blankets are extremely cost-effective because of their reusability. If you have to keep replacing them due to their lack of weather resistance, you lose the cost-benefit; so, invest in a higher quality blanket upfront.

How to Install Outdoor Sound Blankets

The installation of outdoor sound blankets isn’t as difficult as it may seem. The most difficult aspect of installation is setting up or preparing the structure the outdoor sound blankets attach to.

If a fence is not conveniently located around the space you wish to soundproof, consider building a temporary structure that can hold the blankets. Building temporary fencing framework is a great option that will allow you to strategically place the barriers to get the maximum amount of soundproofing, as opposed to haphazardly securing them to closest stable structures.

Once you have identified or built the structure that the outdoor sound blankets attach to, securing the barriers themselves is as simple as zip-tying the grommets or installing hooks to hang them.

Where to Buy Outdoor Sound Blankets

Here at eNoise Control, we provide a wide selection of high-quality outdoor sound blankets to suit a variety of soundproofing needs. eNoise Control’s removable velcro-sealed sound blankets help address sound directly at the source. Our reusable, high temperature, sound control blankets are an ideal fit for compressor noise and fan housing noise applications.

If you are looking for more information or are ready to purchase the best outdoor sound blankets, give us a call at 888.417.1903 or send us an email to info@enoisecontrol.com.

The Ultimate Buyer's Guide for Purchasing Buy Noise Barrier

Your Guide to Buying the Best Outdoor Sound Blankets

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