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Asia Noise News Building Accoustics

The Colors of The Noise

Sound is a collection of random signals that have certain physical characteristics that depend on the sound source. One of the physical characteristics of sound can be seen from the spectrum formed. There is a lot of noise that can be distinguished based on the spectrum character, such as White Noise, Pink Noise, Brownian Noise, Blue Noise, Violet Noise, Gray Noise, and others. In general, what is often used is White Noise, Pink Noise, and Brownian Noise both in measurement and audio testing.

Many people are very familiar with White Noise, usually, the static sound from the Air Conditioner that delivers us to sleep by disguising background noise is always considered White Noise even though technically what we hear from the Air Conditioner fan rotation is not White Noise. Many of the sounds we associate with White Noise are actually Pink Noise, Brownian Noise, Green Noise, or Blue Noise. In the world of audio engineering, there are various types of noise colors with their own unique spectrum, this is produced to give a rich impression on music arrangements, relaxation, and so forth. So, this article will explain that static noise is not always White Noise.

Here are some sound colors that are quite familiar and often discussed in the world of audio engineering:

  1. White Noise

The most commonly mentioned noisy color in everyday life is White Noise. White Noise is called “White” as a symbolization of a white light containing all frequencies evenly or flatly in mathematical calculations. It is said mathematically because, in reality, it is not perfectly flat. The White Noise calculation pattern is evenly distributed if it is calculated using the following equation:

So in the case of White Noise, the signal power becomes:

The resulting spectrum is in the form of a constant straight line like the following graph,

Keep in mind that the graph shown is a logarithmic function and not a linear function where the frequency range at high frequencies is wider than the frequency range at low frequency. Here is a White Noise that can be heard:

2. Pink Noise

Proportionally the pink noise spectrum is seen to decrease on a logarithmic scale but it has equal power in bands that are proportionally wide. This means that pink noise would have equal power in the frequency range from 40 to 60 Hz as in the band from 4000 to 6000 Hz. Since humans hear in such a proportional space, where a doubling of frequency (an octave) is perceived the same regardless of actual frequency (40–60 Hz is heard as the same interval and distance as 4000–6000 Hz), every octave contains the same amount of energy and thus pink noise is often used as a reference signal in audio engineering. The spectral power density, compared with white noise, decreases by 3 dB per octave (density proportional to 1/f ). For this reason, pink noise is often called “1/f noise”. Some people associate pink with red and white where pink is brighter than red and fainter than white so that it is described as a decreased spectrum with values close to a ~ 1. Mathematically, Pink Noise can be calculated using the formulation below:

The depiction of the curve produced by Pink Noise is as follows:

Pink Noise will heard like the following audio file below,

3. Brownian Noise (Red Noise)

Brownian Noise color has several names, some people call it Brown Noise, Brownian Noise, or Red Noise. Brownian was discovered by Robert Brown, the inventor of Brownian Motion (Random Walk or Drunkard’s Walk) where the Noise produced by Brownian Motion is the same as Red Noise / Brown Noise. Described as a red light that is darker than Pink and White, the spectrum formed has the characteristic of a sharp decrease that exceeds a decrease in Pink Noise (1 / f2 or a decrease of 6 dB per octave). Visually the Red Noise value is the boundary of the Pink Noise, together with the White Noise, so the spectrum curve formed is as follows:

Brownian Noise will sound like the following audio file  below:

4. Blue Noise (Azure Noise)

If Red Noise and Pink Noise have a decreased character, then Blue Noise is the opposite. Blue Noise has an uphill spectrum curve characteristic that is inversely proportional to Pink Noise. Blue noise’s power density increases 3 dB per octave with increasing frequency (density proportional to f ) over a finite frequency range. In computer graphics, the term “blue noise” is sometimes used more loosely as any noise with minimal low-frequency components and no concentrated spikes in energy. This can be a good noise for dithering. Cherenkov radiation is a naturally occurring example of almost perfect blue noise, with the power density growing linearly with frequency over spectrum regions where the permeability of the index of refraction of the medium is approximately constant. The exact density spectrum is given by the Frank–Tamm formula. In this case, the finiteness of the frequency range comes from the finiteness of the range over which a material can have a refractive index greater than unity. Cherenkov radiation also appears as a bright blue color, for these reasons.

The curve produced by Blue Noise is as follows:

Blue Noise will sound like the following audio file  below:

5. Violet Noise (Purple Noise)

If Blue Noise is the opposite of Pink Noise, then Violet can be categorized as the opposite of Red or Brownian Noise. This can be seen from the addition of the power density of Violet Noise which is 6 dB per octave with increasing frequency value. The proportional density of Violet Noise or often also called Purple Noise is f2 over a finite frequency range. Violet Noise is also known as differentiated white noise, due to its being the result of the differentiation of a white noise signal.

The curve produced by Violet Noise is as follows:

Violet Noise will sound like the following audio file  below:

6. Grey Noise

Gray Noise is a randomized White Noise that is correlated with the same psychoacoustic noise curve or can be said to be an inverse A-weighting curve, with a specific frequency range that gives the impression or perception that this sounds equally loud at all frequencies. This is in contrast to standard white noise which has equal strength over a linear scale of frequencies but is not perceived as being equally loud due to biases in the human equal-loudness contour.

The curve produced by Grey Noise is as follows:

Grey Noise will sound like the following audio file  below:

Written by:

Betabayu Santika

Acoustic Design Engineer

Geonoise Indonesia

Beta@geonoise.asia

Sources:

Pics: Noise Curves By Warrakkk – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=19274696

Hartmann, William M. Signals, sound, and sensation. Springer Science & Business Media, 2004.

“Federal Standard 1037C”. Institute for Telecommunication Sciences. Institute for Telecommunication Sciences, National Telecommunications and Information Administration (ITS-NTIA). Retrieved 16 January 2018.

Lau, Daniel Leo; Arce, Gonzalo R.; Gallagher, Neal C. (1998), “Green-noise digital halftoning”, Proceedings of the IEEE, 86 (12): 2424–42, doi:10.1109/5.735449

Joseph S. Wisniewski (7 October 1996). “Colors of noise pseudo FAQ, version 1.3”. Newsgroup: comp.dsp. Archived from the original on 30 April 2011. Retrieved 1 March 2011.

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Asia Noise News Building Accoustics Noise and Vibration Product News

The Nano-guitar String that Plays Itself

Scientists at Lancaster University and the University of Oxford have created a nano-electronic circuit which vibrates without any external force.

Using a tiny suspended wire, resembling a vibrating guitar string, their experiment shows how a simple nano-device can generate motion directly from an electrical current.

To create the device, the researchers took a carbon nanotube, which is wire with a diameter of about 3 nanometers, roughly 100,000 times thinner than a guitar string. They mounted it on metal supports at each end, and then cooled it to a temperature of 0.02 degrees above absolute zero. The central part of the wire was free to vibrate, which the researchers could detect by passing a current through it and measuring a change in electrical resistance.

Just as a guitar string vibrates when it is plucked, the wire vibrates when it is forced into motion by an oscillating voltage. This was exactly as the researchers expected.

The surprise came when they repeated the experiment without the forcing voltage. Under the right conditions, the wire oscillated of its own accord.

The nano-guitar string was playing itself.

Lead researcher Dr Edward Laird of Lancaster University said: “It took us a while to work out what was causing the vibrations, but we eventually understood. In such a tiny device, it is important that an electrical current consists of individual electrons. The electrons hop one by one onto the wire, each giving it a small push. Usually these pushes are random, but we realized that when you control the parameters just right, they will synchronize and generate an oscillation.”

So what note does the nano-guitar play?

“The nanotube is far thinner than a guitar string, so it oscillates at much higher frequency — well into the ultrasound range so no human would be able to hear it.

“However, we can still assign it a note. Its frequency is 231 million hertz, which means it’s an A string, pitched 21 octaves above standard tuning.”

The nano-oscillator could be used to amplify tiny forces, such as in novel microscopes, or to measure the viscosity of exotic quantum fluids. These experiments will be pursued in a new laboratory that Dr Laird is setting up in the Physics Department at Lancaster, supported by a €2.7M grant from the European Union.

Credit: https://www.lancaster.ac.uk/news/the-nano-guitar-string-that-plays-itself

Written by: Phawin Phanudom

Categories
Asia Noise News

A Review of Acoustics in the Hospitality Industry: A Subjective and Objective Analysis

Many bars, cafés, and restaurants have been built in Asia, that is one of the indications that the hospitality industry is moving forward. Our need for entertainment, refreshing our mood, and communication with friends, family members, or business clients are reasons why we need the hospitality Industry such as; bars, cafés, and restaurants as a place for us to do that kind of activities. Comfortableness becomes a top priority to determine if a bar, café, or restaurant is a pleasant place to be or not. One of the criteria is comfortableness in acoustics aspect, how easy the customers can have a conversation, a relaxed ambience and quietness. In Asia, especially in developing countries, acoustic comfort in bars, cafes or restaurants is not yet a major concern, even though the effect will be huge for their visitors’ comfort. One example of the impact of bad acoustic design on a cafe or restaurant is the difficulty of communicating, even though one of the things that visitors want to do is chat with family, friends or work partners. This situation will give a bad impression of the café or restaurant and reduce the number of visitors to the café or restaurant.

In this article, the author will discuss the research conducted by Lauren H. Christie and J. R. H. Bell Booth – Victoria University of Wellington. This study is titled “Acoustics in the Hospitality Industry: A Subjective and Objective Analysis” this research examining several Bars, Cafes, and Restaurants around Wellington CBD related to acoustic comfort based on objective and subjective parameters which are then compared to AS / NZA 2107:2000.

The results of the research at the cafés, bars and restaurants in Wellington CBD found that the average noise level that occurred was 80 dBA and could even reach as high as 110 dBA. If it is compared with the level of sensitivity of human hearing to speech that only ranges from 48 dBA to 72 dBA [AS / NZA 2107: 2000] this very much exceeds the limit. The NC (Noise Criteria) suggested in this study are:

  • Bar : 45 – 50 dBA
  • Café : 45 – 50 dBA
  • Restaurant : 35 – 50 dBA

As reviewed earlier, research conducted by Lauren H. Christie and J. R. H. Bell Booth takes 2 parameters, they are subjective and objective parameters. Subjective consists of a Survey Questionnaire that is spread to visitors about the information conveyed, the ability to listen, the dominant difficulties that occur, and the desired ideal conditions. This is called subjective because it is qualitative and is adjusted to personal tendencies. The second parameter is Objective, consisting of measured parameters such as BN (Background Noise), Leq, RT (Reverberation Time), STI (Normal, Rise, Loud, Shout).

BN is measured by measuring the level of sound pressure in conditions without visitors, the use is as an acoustic base value without additional noise. Leq is the average noise over a period of time, this is done as sample information on the noise value of the place. RT or Reverberation Time is the time required for the sound to decay as much as 60 dB, this parameter is used as a base for evaluating the comfort of the conversation or music in a room, RT that is too high will make someone difficult to communicate because the sound will be reflected and reduce the clarity of the conversation. STI or Speech Transmission Index is a parameter to assess the level of comfort in terms of listening to speech or conversation, the value ranges from 0 to 1 with a value of 1 is perfect or very clear STI.

The age range of visitors looks similar if evaluated based on the survey, most visitors in a bar are under 25 years old, while in the cafés and restaurants most visitors are in the range of 25 – 35 years old. Based on the survey results, the need for acoustic quality related to the highest conversations is in restaurants, followed by cafés and bars. This is very clear because the restaurant visitors have a lot of verbal interaction or direct communication when eating. At the café, there tends to be less communication and more listening to the ambiance and relaxing music with less communication if we compare it with a restaurant. The last ranked is the bar, visitors will only listen to music to arouse their mood and rarely communicate. The highest source of noise comes from other visitors’ communications, which is followed by the sound of music and kitchen equipment.

Acoustic comfort based on survey results or subjective parameters are as follows:

Restaurant

  • Restaurants are expected to have a low Background Noise and a good STI, but the actual situation in most of the restaurants researched is far from that.
  • Privacy is a very important variable in a restaurant.
  • The clarity in terms of speech is low.
  • Visitors in the restaurants are very difficult to be heard/understood when they are talking.

Bars

  • Bar customers said that a bar is more acceptable to noise than a cafe or restaurant.
  • Even though it is difficult to communicate, the bar can be accepted by visitors.
  • Bar customers need more effort to communicate.
  • The type of people who visit the bar are people who are accustomed to noisy environments.

Café

  • People who often visit a café find it easy to communicate at the café.
  • Clarity of speech is seen as a more important factor than the visitor’s environment.
  • Café is also rated as the most unacceptable environment from this acoustic-related survey.

Based on objective parameters, the results are: BN (Background Noise is in the range of 34 dBA (Leq) to 81 dBA (Leq), where 60% of the data is worth more than 50 dBA (Maximum level in AS / NZA 2107: 2000). After measuring with visitors inside, the level of the noise reaches 25dB beyond the maximum visited level, but when compared to the OSH recommendation safety limit, 85 dBA (Leq), the value is still below the threshold (the highest level of measurement is 81 dBA).

For the RT value, both the bars, cafés and restaurants are within the standard of <1.0 S. STI rating is found to be very diverse, but from the use of the 4 types of sound that are normal, raised, loud, and shout the same pattern is obtained, the higher the sound level, the better STI. From this research, we know that there are differences in preferences of acoustic comfort factors in bars, cafes, and restaurants. The difference in preferences is due to differences in the main functions of each hospitality industry. At the restaurant, visitors expect to be able to communicate well in one scope of the table and maintained privacy from the scope of another table. At the café, the need for tranquility is the main thing and the need for communication is not as high as the restaurant. At the bar, the main needs of visitors are listening to music and not too concerned about communication difficulties.

So, has your hospitality industry considered acoustic comfort? It’s a very important aspect to keep visitors coming back to your venue!

Written by:

Betabayu Santika

Acoustic Design Engineer

Geonoise Indonesia

Beta@geonoise.asia

Source:

AS/NZS 2107 (2000). Acoustics – Recommended design sound levels and reverberation times for building

interiors. Australian/New Zealand Standards: Sydney/Wellington.

Bell-Booth, J. R.H. (2004). Methodology Research.

Christie, L. H. (2004). Acoustical Comfort: Research Design into Measuring Restaurants and

Bars Acoustic Environments.

Christie, L. H. & Bell-Booth, J. R.H. – Acoustics in the Hospitality Industry: A Subjective and Objective Analysis

Categories
Asia Noise News

Calibration

Sound measurement is one of the measurements which is considered to be important in a lot of different industries. For example, automotive, manufacture, HSE, research and so on. One of the aspect that is important for all measurements are its calibration. Calibration is a process of documenting and adjusting the reading of measurement instruments with a traceable reference. 

The frequency range of acoustic measurement in air is wide, from infrasound to ultrasound. From tenth hertz to 200 kHz. It is measured in a wide range of dynamic range too, from 20 micropascal to 20 kilopascal. Therefore, to be able to conduct these measurements in a wide range of frequency and dynamic, different kinds of microphone is used.

Most measurement microphones and reference microphones is condenser microphone. This type of microphone is widely chosen because of its flat frequency response and a good mechanical stability. The standard used for measurement microphone is IEC61094-4 which is called working standard microphones, abbreviated WS. WS microphones are categorized into 3 types based on its diameter which are 23.77 mm, 12.7 mm and 6.35 mm. These three microphones are called WS1, WS2 and WS3 respectively.

Another standard is used for Laboratory Standard Microphone, abbreviated LS, which is IEC61094-1. Similarly to WS, LS can be categorized by its diameter, which are LS1 with 23.77 mm and LS2 with 12.7 mm diameter. LS microphone is designed so that it can be fitted into calibration coupler and is normally used by national metrology institute as a national reference in a country. Both of the standards mentioned above specify dimension, sensitivity, frequency response, acoustic impedance, dynamic range, ambient influence and stability.

Condenser microphone is a reciprocal transducer. This microphone can work as a microphone by converting acoustic signal into electric, as well as working as a sound source by converting electrical input into acoustic output. This is why condenser microphones can be calibrated by a calibration method called reciprocity.

Before we discuss further about the calibration method, it is useful to discuss about sound field and the type of microphone used to measure in such fields. There are three types of sound field in general. In a cavity which dimension is smaller than a quarter of the measured wavelength, the soiund field is called pressure-field. This field happens in a calibration coupler for microphone calibration, telephone and hearing aids, for example. Sound field in an anechoic chamber or outdoor where sound can propagate without obstacles is called free-field. While sound field in a reflective room is called diffuse-field. 

All types of microphones can influence the sound field which is being measured, including condenser microphone. Microphones that are used in cavities should have a stiff diaphragm, or in another word has a high acoustic impedance. For free-field condition, microphones that are chosen ideally has a diameter less than 5-7% from the wavelength of the sound being measured. In practice, this rarely happens, so that the influence has to be taken into account in the measurement results. Similar situation happens in diffuse-field, although the influence is relatively smaller.

Note that the influence in the free-field and diffuse-field depends only on the dimension of the microphone’s body. Because of this reason, the influence only have to be measured once for the same microphone model. After the influence is defined, it can be applied to all the same microphone of the same model. 

Let’s go back to reciprocity calibration. This method was invented in the 1940s. This method has been developed and standardised which makes the method one of the most widely used calibration techniques to determine microphone’s response in pressure-field and free-field. The calibration method is based on transfer function of two microphones which are coupled as microphone and sound source.

The two microphones are coupled in a well-defined acoustic environment. The transfer function which is the ratio between output voltage of the sensor and input current of the source is measured. This ratio is called electrical transfer impedance (Ze). Furthermore, by knowing the acoustic transfer impedance (Za), the product of the sensitivity of the two microphones can be defined by this equation.

Where M1 and M2 is the sensitivity of microphone 1 and microphone 2, Ze/Za is the ratio between electric and acoustic transfer impedance.

By using three microphones (1,2,3) and defining three impedance ratio equations (A,B,C) for three possible combinations (1-2, 1-3, 2-3), the sensitivity of three microphones can be calculated by solving these three equations.

Some national metrology institutes are doing reciprocity calibration for laboratory standard microphones. The frequency ranges from 20Hz to 10kHz for LS1 and 20Hz to 20kHz for LS2. Some of the institutes has experience in calibrating lower or higher frequency range.

Categories
Asia Noise News

Profound November News

SIT-mounted sensor for Wave Hammer

The Profound mounted accelerometer for the SIT-series has been custom-designed for high performance integrity testing of installed foundation piles. Especially for large diameter bored piles this sensor enables optimal circumstances to perform the measurement.

Advanced design and application
The SIT-mounted sensor is an alternative to the hand-held sensor whereby the sensor is fixed on the pile head using a separate mounting plate. One or more mounting plates can be mounted on the pile head in advance of the actual measurement. During the measurement the stiff connection between the mounted sensor and pile head ensures optimal high-quality measurement results, asthe mounted sensor registers exceptionally well the response to the hammer blow. Thus providing users with accurate information about the pile shaft and possible defects.
The mounted accelerometer is ideal to be used in combination with the Wave Hammer range for large diameter piles.

News from Soil Instruments Ltd.: GEOSmart

GEOSmart is an in-place inclinometer consisting of closely spaced MEMS 0.5 metres apart. The sensors are mounted on stainless steel tubing with a single cable running the length of the string which reduces the number of cables protruding from the top of the borehole. GEOSmart is installed in either PVC Schedule 40 or 70mm casing and is used to monitor displacement in geotechnical applications including diaphragm walls, embankments, retaining walls, landslides and potential slope failures. Due to its lightweight robust construction with joints capable of bending up to 90o, GEOSmart is conveniently transported to site and can be installed by one site technician. At the end of the project GEOSmart can be removed and reused whereby the length of the string can be easily adapted.

New features vibramonitoring.com

With the new features on vibramonitoring.com we have created a new datasheet. Please contact us for the new datasheet.

Partnership VDV : online monitoring

We are proud to announce that from now on we have entered into a partnership with Vista Data Vision (VDV). VDV supplies leading software for the visualisation of data for geotechnical monitoring projects.

The VDV platform offers extensive and straightforward options presenting all measurement data of the different instrumentation in one project to your clients. The platform offers numerous options for setting threshold values, alarms, user accounts and for combining information from various equipment such as: VIBRA systems, Robotic Total Stations, IPI sensors, noise monitoring systems, air quality monitors. It is also possible to integrate webcams.
VDV Burst Data allows to import high speed dynamic data such as from instruments made by Profound. The data is imported into the VDV database and can then be viewed with all other data types already supported by VDV.

Exhibitions

In October we attended 2 Dutch conferences: the 23rd GTL for Sound, Vibration and Air Quality in Hoevelaken and the Geotechnical conference in Breda. The reactions to all the new products like the Wave Hammer, mounted sensor, the partnership with VDV and the early impressions of the VIBRA-r were very positive.
Our special guest Chris Wembridge of Soil Instruments Ltd. demonstrated the GEOSmart system himself at the Geotechnical conference.

Categories
Building Accoustics

Researchers Develop ‘Acoustic Metamaterial’

Boston University researchers, Xin Zhang, a professor at the College of Engineering, and Reza Ghaffarivardavagh, a Ph.D. student in the Department of Mechanical Engineering, released a paper in Physical Review B demonstrating it’s possible to silence noise using an open, ring-like structure, created to mathematically perfect specifications, for cutting out sounds while maintaining airflow.

They calculated the dimensions and specifications that the metamaterial would need to have in order to interfere with the transmitted sound waves, preventing sound—but not air—from being radiated through the open structure. The basic premise is that the metamaterial needs to be shaped in such a way that it sends incoming sounds back to where they came from, they say.

As a test case, they decided to create a structure that could silence sound from a loudspeaker. Based on their calculations, they modeled the physical dimensions that would most effectively silence noises. Bringing those models to life, they used 3-D printing to materialize an open, noise-canceling structure made of plastic.

Trying it out in the lab, the researchers sealed the loudspeaker into one end of a PVC pipe. On the other end, the tailor-made acoustic metamaterial was fastened into the opening. With the hit of the play button, the experimental loudspeaker set-up came oh-so-quietly to life in the lab. Standing in the room, based on your sense of hearing alone, you’d never know that the loudspeaker was blasting an irritatingly high-pitched note. If, however, you peered into the PVC pipe, you would see the loudspeaker’s subwoofers thrumming away.

The metamaterial, ringing around the internal perimeter of the pipe’s mouth, worked like a mute button incarnate until the moment when Ghaffarivardavagh reached down and pulled it free. The lab suddenly echoed with the screeching of the loudspeaker’s tune.

How acoustic metamaterial works – Geonoise Asia
How acoustic metamaterial works – Geonoise Asia

Now that their prototype has proved so effective, the researchers have some big ideas about how their acoustic-silencing metamaterial could go to work making the real world quieter.

Closer to home—or the office—fans and HVAC systems could benefit from acoustic metamaterials that render them silent yet still enable hot or cold air to be circulated unencumbered throughout a building.

Ghaffarivardavagh and Zhang also point to the unsightliness of the sound barriers used today to reduce noise pollution from traffic and see room for an aesthetic upgrade. “Our structure is super lightweight, open, and beautiful. Each piece could be used as a tile or brick to scale up and build a sound-canceling, permeable wall,” they say.

The shape of acoustic-silencing metamaterials, based on their method, is also completely customizable, Ghaffarivardavagh says. The outer part doesn’t need to be a round ring shape in order to function.

“We can design the outer shape as a cube or hexagon, anything really,” he says. “When we want to create a wall, we will go to a hexagonal shape” that can fit together like an open-air honeycomb structure.

Such walls could help contain many types of noises. Even those from the intense vibrations of an MRI machine, Zhang says.

According to Stephan Anderson, a professor of radiology at BU School of Medicine and a coauthor of the study, the acoustic metamaterial could potentially be scaled “to fit inside the central bore of an MRI machine,” shielding patients from the sound during the imaging process.

Zhang says the possibilities are endless, since the noise mitigation method can be customized to suit nearly any environment: “The idea is that we can now mathematically design an object that can block the sounds of anything”.

Source:

https://phys.org/news/2019-03-acoustic-metamaterial-cancels.html

Categories
Asia Noise News Building Accoustics

Noise and Vibration Monitoring for Construction Sites

In a densely populated city like Bangkok, most of the construction projects are surrounded by condominiums, offices or residential areas. The construction sites must control the noise and vibration that may affect the surroundings. Construction sites need to control the noise and vibration levels that they produce following the EIA standard.

To manage this, noise and vibration instruments are installed which automatically will send alarms to the construction company if the thresholds are exceeded.

Noise Monitoring Station

Sound level meter class 2 according to IEC61672-1 standard which can collect the data of SPL, LEQ and LMAX. These instruments are calibrated before they are installed at a construction site. The system has a LED display and warning light when noise levels in the site are over a trigger level, which is referred to in the standards for maximum sound levels around construction sites.

According to the announcement of National Environment Board no.15 BE.2540 (1997) in the topic of “Standard loudness”, the average sound 24 hour must not exceed 70 dBA and the maximum peak level must not exceed 115 dBA.

Sound level meter are designed to be used outdoors and an additional LED display was added by Geonoise which is a professional sound and vibration company. Sound level meter with LED display also can analyse the loudness in percentile (Statistical,Ln) or analyse the frequencies in 1/1 and 1/3 octave bands. In addition to storing vibration data, you can also create level notifications in Alarm Alert format before vibration levels exceed the standard value for monitoring the activities being performed.

Vibration Monitoring

In the construction industry, transportation Industry and most large industries vibrations will occur.
High vibration levels will cause structural damage to buildings, bridges, structures as well as nuisance or health risks to occupants in exposed (residential) buildings.

Therefore, it is necessary to comply with the standard of vibration in a building according to the Announcement of the National Environment Board Announcement No. 37, BE 2553 (2010) Re: Determination of Standard Vibration to Prevent Impact on Buildings and the measuring instruments need to comply with DIN45699-1.

At construction projects in Bangkok, most cause a lot of unwanted noise and vibrations. Vibration caused by construction projects are caused by piling work as well as the increased traffic of large trucks that enter and exit the construction site. To prevent that vibration levels will be exceeded, a vibration monitoring system will have to be installed.

The Announcement of the National Environment Board No. 37, BE 2553 Vibration standards to prevent impacts on buildings is the main regulation to comply with for construction sites in Thailand. The vibration standards are derived from DIN 4150-3 whereas buildings are classified into 3 types.

Building types according to DIN 4150-3:

  • Type 1 buildings such as commercial buildings, public buildings, large buildings, etc.
  • Type 2 buildings such as residential buildings, dormitories, hospitals, educational institutions, etc.
  • Type 3 buildings, such as archaeological sites or buildings that cultural values but not strong, etc.

In addition to storing vibration data, you can also create level notifications in Alarm Alert format before vibration level exceed the standard value for monitoring the activities being performed.

Categories
Asia Noise News Building Accoustics

Exploring Jakartan Public Transportation Through The Sound

Jakarta, the capital city of Indonesia, is home to 10 millions of Indonesia population. Recently the Indonesian government is being sued by a group of activists and environmentalists due to the unhealthy air quality in Jakarta. The plaintiff hopes that through the lawsuit, the Indonesian government can improve existing policies to address the air pollution issues.

On 18 Jul, according to the Switzerland-based pollution mapping service AirVisual, the Air Quality Index (AQI) of Jakarta is 153, categorized as unhealthy and may cause increased aggravation of the heart and lungs. The recommendation upon this condition is to wear a pollution mask and use air purifiers inside the room. The AQI Measures five criteria air pollutants (particulate matter, sulphur, dioxide, carbon monoxide, nitrogen dioxide, and ozone), and converts the measured pollutant concentration in a community’s air to a number on a scale of 0 to 500.

Air Quality Index – AirVisual

Jakarta is one of the largest urban agglomerations in the world. The uncontrolled increase in urban population is proportional to the number of the vehicle in Jakarta. According to Badan Pusat Statistik (Statistics Indonesia), the growth of motorized vehicle in Jakarta is 5,35% every year, on the other hand, this growth will increase the number of pollution in Jakarta. This statement is supported by the acting head of Jakarta Environment Agency, Andono Warih, the fuel residue of motorized vehicles was the main contributor to severe air pollution as 80 per cent of vehicles powered by diesel fuel operated from Jakarta Greater Area (Jabodetabek) to the capital.

Jakartan can contribute directly to overcome air pollution issues. Public transportation is an environmentally friendly mode of getting around. Because public transportation carries many passengers on a single-vehicle, thus it can reduce the number of vehicles as well as reducing the number of emissions from transportation in a dense urban area. Further, public transportation can help Jakarta to reduce the smog, to meet air quality standards and to decrease the health risk of unhealthy air quality. 

The urban transportation system in Indonesia consists of buses, trams, light rail, metro, rapid transit and ferries. Particularly in Jakarta, urban rail-based transportation, such as Commuter Line Train, Light Rail Transit (LRT) and Mass Rapid Transit (MRT), provides mobility and access to the urban area.

MRT Jakarta Phase 1 – MRT Jakarta

The first phase of MRT Jakarta (MRT-J) has been operating since March 2019. In daily operation, the train runs from Lebak Bulus Grab Station to the Bundaran HI Station. There are 13 stations along the railway; the underground stations are Bundaran HI, Dukuh Atas BNI, Setiabudi Astra, Bendungan Hilir, Istora Mandiri, and Senayan Station. Meanwhile, the overground stations are ASEAN, Blok M, Blok A, Haji Nawi, Cipete Raya, Fatmawati, and Lebak Bulus Grab Station. The MRT-J only needs 30 minutes to travel along the 16 kilometres railway, starting from Lebak Bulus Grab Station in South Jakarta to the Bundaran HI Station in Central Jakarta.

There are 16 train lines available to take the passengers getting around. Based on the MRT-J website, In weekdays operation, the trains operate at 05.00 WIB to 24.00 WIB with a total of 285 trips. Meanwhile, in weekend operation, the trains run at the same hour with a total of 219 trips.

During the promo operation (1 April – 12 May), the average number of daily passengers reached 82,643, whereas after the full tariff was applied, the average per day was 81,459.

The following pictures will show you the scenes of MRT Jakarta.

So what do you think? Have you tried getting around using MRT Jakarta? If you have never, try immediately and feel the different sensation of Public Transportation in Indonesia.

Further, through this article, I would like to invite you, explore the MRT Jakarta through a different perspective, that may be for a group of people this method is still rarely used, a sound.

Do you realize that sound can tell us about character, place, and time? Sometimes, it informs us in ways visuals can’t, and that is the idea of what we are going to do right now. Later you will hear, a file of recorded sound of MRT-J in its daily operation.

The sound was recorded by the soundwalk method, any excursion whose primary purpose is listening to the environment. It is exposing our ears to every sound around us no matter where we are. We may be at home, walking across a downtown street, or even at the office. Meanwhile, in this case, our environment is inside the line of MRT Jakarta. The goal is to capture any sound sources that exist during the operation of MRT-J, including the activity of the passengers.

The sound was recorded by using a mounted microphone on the iPhone X at a level of 1.2 m above the ground. The following sound is a recorded environment while the MRT-J was travelling from Bundaran HI Station to Setiabudi Astra Station, the duration of recording sound is 4 minutes and 40 seconds. Please use an earphone or any similar devices to listen to the audio for a better experience.

Caution: please set the volume around 50 – 70 % of the maximum volume.

After listening to the sound, can you identify what sound sources are presented in the recording? Here are the sound sources that I have identified:

  1. Engine sound increases speed
  2. Public Address system
  3. Engine sound
  4. Rail friction
  5. Passengers’ activities (cough, sneeze, conversation, footsteps, etc.)
  6. The sound of the door opening
  7. Brake squeak

Now we have identified the sound sources that are presented in the recording. But, do you know how many decibels that I have to endure while travelling using the MRT-J? In this article, manual measurements of noise levels were performed with a sound level meter in the MRT Jakarta with passengers on its usual route. A-weighted sound level measurements were recorded directly from one station to the next during the time between 08:00 and 09:00, using a calibrated microphone on a stand at a level of 1.2 m above the ground. The results of equivalent continuous A-weighted noise levels Leq (LAEq) in the MRT-J with passengers on its usual route from one station to the next is shown in Chart 1. 

Leq is the A-weighted energy means of the noise level averaged over the measurement period. The results from the measurements show that the A-weighted noise level is varied between 77 dB to 82 dB. Further, if we look closely into the Chart, the noise level is fluctuating. It can be caused by a lot of factors, such as: 

  1. The position of MRTJ (When MRT-J inside the tunnel, the noise can be levelled up due to the reflection phenomenon).
  2. Speed (The machine indicates producing a higher noise when in the maximum speed).
  3. Path Crossing.
  4. The Public Address System Volume.

Moreover, the level of continuous noise in Chart 1 represents a quite noisy environment. According to The National Institute on Deafness and Other Communication Disorders, states that Long or repeated exposure to sound at or above 85 dB can cause hearing loss. Thus, according to the measurement results, I suggested you wear ear protection during commuting by MRT-J. The earplug is one of the equipment that we can use to protect our hearing; you only need to spend a few thousand rupiahs for this. Wearing earplugs can help you to reduce the noise by 18 – 34 dB, it depends on the models/brand. For more accurate results, we need to do a complex measurement, such as:

  1. Add measurement point (In this article, the measurement was done only in a measurement point, at the second car of the line).
  2. Add a velocity as a measured parameter.
  3. Add the measurement time; the measurement can be done during the operation hour, non-stop. (05:00 – 24:00 WIB).

Nonetheless, the idea of showing the measurement results is spreading noise awareness. Noise sticks with you around, even common sounds you hear at work or home can contribute to long term hearing loss and other health risks, they are everywhere, but only a few people are aware of it. Noise pollution is a health threat nobody is talking about. Here are some parameters to help you determine acceptable — and dangerous — noise levels:

  • 45 dB: nightly noise ordinance threshold set by many municipalities concerned with industrial noise exposure for residents
  • 65 db+: exposure for prolonged periods can cause physical and mental fatigue
  • 85 dB+: can cause permanent hearing loss if exposed for extended periods
  • 85-120 dB: dangerous over 30 minutes of exposure
  • 120-130 dB: can cause permanent hearing loss for exposure over 30 seconds
  • 130 dB+: not only are these noises painful, but hearing protection should always be used if avoidance is not possible.

Everyone needs to take care of their ears and hearing, as damage to the auditory system could be irreparable. The loss because of the noise exposure is gradual; you might not notice the signs, or you ignore them until they become more apparent. Please do protect your ears. 

Reference:

https://www.theguardian.com/world/2019/jul/02/jakarta-residents-to-sue-government-over-severe-air-pollution

http://support.airvisual.com/knowledgebase/articles/1185775-what-is-aqi

https://doi.org/10.1016/j.ecss.2018.10.017

https://jakarta.bps.go.id/publication/2018/10/03/cb1285d8dbe8be8754a5830d/statistik-transportasi-dki-jakarta-2018.html

https://en.tempo.co/read/1214627/jakarta-air-pollution-mostly-caused-by-motorized-vehicles-agency

https://www.nationalexpresstransit.com/blog/why-is-public-transportation-good-for-the-environment/

https://www.businesstimes.com.sg/asean-business/indonesia-accelerating-urban-transportation-development-with-public-private

Westerkamp, Hildegard (1974). “Soundwalking”. Sound Heritage

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5308171/

https://www.sensear.com/blog/noise-is-everywhere-how-to-deal-with-it-does-it-create-a-dangerous-environmenthttps://www.womenshealthmag.com/health/a19599097/noise-pollution/

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The Ultimate Solution for Dissertation Introduction

The Chronicles of Dissertation Introduction

The last portion of your introduction ought to be the dissertation outline. A dissertation introduction begins with the presentation of your primary issue. Possibly the most important portion of your paper, it informs about the topic of your writing and provides a background to your research. Someone might believe that writing a dissertation introduction is quite a boring undertaking. The main reason why the introduction for a dissertation is the toughest area of the paper is that its primary purpose is to earn a reader interested in the subject you’re researching. Writing a dissertation introduction needs a particular format and application of academic language. If you would like to learn to compose the debut of the dissertation you’ll be able to search it to the web.

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Writing style and duration of the introduction The introduction is the overview of the entire dissertation. Writing an extremely comprehensive introduction is another typical issue. It is necessary to think of an introduction that’s interesting enough to readers they wish to discover more.

You introduction will function as the very first impression of your work. Always keep in mind that the introduction shouldn’t be too long as it’s anticipated to bore the readers. What you have to do in dissertation introduction, nevertheless, is demonstrate your competence and research abilities. Dissertation introduction is part of your dissertation project that includes the big purposes of your investigation and the means by which you need to achieve them. Someone might believe that writing a dissertation introduction is pretty a tedious endeavor. Portions of the introduction In the sample dissertation introduction, you can observe portions of the introduction which might incorporate the reach of the study, practical and scientific relevance of the analysis.

Dissertation is not something that may be ready every day or two. A dissertation typically is broken up into chapters. The Structure Your standard ten page dissertation ought to have the introduction on a single page, with approximately 3 paragraphs.

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The Do’s and Don’ts of Korean Audio Translation

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