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The article presents abstracts on noise and vibration topics including the use of a general model for mapping of urban background noise, the research project for sound insulation properties in multilayer building partitions, and low frequency subjective effect in road traffic noise.

The article presents abstracts on papers related to noise and vibration including "Low Frequency Acoustic Resonances in Urban Courtyards," by M. Molerón and colleagues, "Predicting the Sound Insulation of Lightweight Sandwich Panels," by J. Davy and colleagues, and "Advances in Experimental Aeroacoustics," by G. Raman and colleagues.

Recently, research on new techniques of single-chamber mufflers hybridized with an internal extended tube has been addressed; however, the research work on space-constrained multi-chamber mufflers conjugated with multiple internal extended tubes which may increase the acoustical performance within a specified back pressure has been neglected. Therefore, the main purpose of this paper is not only to analyze the sound transmission loss (STL) of a space-constrained tube-extended muffler equipped with 1-3 chambers but also optimize the best design shape under a specified pressure drop. In this paper, the four-pole system matrix for evaluating acoustic performance - sound transmission loss (STL) - is derived. Moreover, a particle swarm optimization (PSO), a robust scheme used to search for the global optimum by imitating bird flocking or fish schooling behavior to achieve a self-evolving system, has been used during the optimization process. Before dealing with a broadband noise, the STL's maximization with respect to a one-tone noise is introduced for a reliability check on the PSO method. Additionally, an accuracy check of the mathematical model is performed. To appreciate the acoustical ability of the internal extended tubes and chambers inside a muffler, three kinds of multi-chamber mufflers hybridized with extended tubes (one-chamber, two-chamber, and three-chamber mufflers) have been assessed and compared. Results reveal that the maximal STL is precisely located at the desired tone. Consequently, a successful approach used for the optimal design of the tube-extended mufflers equipped with 1∼3 chambers under space and back pressure constrained conditions has been demonstrated. [ABSTRACT FROM AUTHOR]

Noise pollution around airports is one of the most important problems in environmental acoustics. The incessant development of modern societies is continuously increasing the demand for air transport, and airports have to grow to adapt their operational capacity to the new requirements. On the other hand, the economic activity related to airports is closely linked to the expansion of built-up areas around them. Consequently, two completely incompatible land uses are forced to coexist, causing airport capacity to remain limited while the inhabitants do not cease to be annoyed by aircraft noise. Although there are several international initiatives setting the focus on the reduction of noise at the source, people living in residential areas around airports need urgent solutions. Among others, the implementation of sound insulation programs is one of the most widely-adopted solutions worldwide, as it allows a reduction of sound levels in the interior of dwellings, while the operational capacity of the airport remains unaffected. The definition and application of a sound insulation program is a very complex process that needs to manage several opposing factors: health, annoyance, airport capacity, economic costs of insulation measures… In this paper we describe the case of Spanish airport insulation programs. We set the focus on a concise description of the full process, from the creation of noise maps, to the checking of installed soundproofing measures, as carried out by the Spanish administration. As a result of this process, thousands of dwellings and houses have been acoustically insulated to meet indoor noise comfort criteria in Madrid, Mallorca and Malaga airports, among others. [ABSTRACT FROM AUTHOR]

The article presents abstracts on noise which include promulgation of noise emission standards for assessment of noise impact in industrial facilities in the U.S., building regulations for airborne and impact sound insulation between dwellings in Europe, and the extension of Cremer's model studying sound insulation of single leaf walls.

The article presents abstracts of studies related to acoustics, sound and noise including "Community Responses to Road Traffic Noise in Hanoi and Ho Chi Minh City," by Hai Yen Phan et al. which appeared in the 2010 Vol. 71 issue of "Applied Acoustics," "Influence of Sound Source Recognition on Annoyance Judgment," by Preis et al. published in the 2008 Vol. 56 issue of "Noise Control Engineering," and "Meta-Material Sound Insulation," by E. Wester et al. published in the 2009 Vol. 16 of "Building Acoustics."

The article presents summaries of studies on noise and vibration published in various periodicals. They include "Suppression of Brake Squeal Noise Applying Finite Element Brake and Pad Model Enhanced by Spectral-Based Assurance Criteria," "Low Frequency Sound Insulation Using Stiffness Control With Honeycomb Panels," and "Adaptive Positive Position Feedback for Actively Absorbing Energy in Acoustic Cavities."

The article focuses on perception and annoyance due to vibrations in dwellings generated from ground transportation. Topics discussed include improvement in quality of buildings regarding sound insulation has made it possible to reduce noise exposure, adverse effects of vibrations that effect the health and well-being of human beings is vibration annoyance, and need of research in various disciplines such as human sciences, physics to assess vibration annoyance.

The article offers world news briefs on aircraft noise topics. The draft federal guidelines by aviation authorities in Sydney, New South Wales, reveal a plan to classify an extra 128 square kilometer of Sydney as affected by aircraft noise without flight pattern change. A nine-year program has soundproofed houses within 65 decibel contour of Barnes Regional Airport in Westfield, Massachusetts.

An abstract of the article "Facade Elements for Natural Ventilation and Sound Insulation," by B. de Araujo and S. Bistafa is presented.

The article reports on a study which examines the relationship between sound insulation performance and the degree of conversation leakage in the parameters of the test sound fields with different noise level at adjacent rooms.

Façade sound insulation can be improved by using high performance components or by modifying the shape of the façade. In many cases, when high acoustic insulation levels are required, the use of high performance components cannot be sufficient, for technical or economic reasons. The European standard EN 12354-3 [1] gives a simplified method to estimate the influence of the façade shape in the reduction of sound pressure level at the outside of the building envelope. In particular, the influence of the façade is evaluated for a number of building typologies as a function of the general direction of the incoming sound and of the acoustic absorption coefficient of the surface of the underside of the balcony. In the paper, the results of a study on the influence of the façade shape on the incoming sound are evaluated with reference to a great number of different typologies of buildings façades. The study has been carried out by means of a prediction software based on the modified theory of the ray tracing (pyramid tracing). Moreover, some of the configurations analysed with the prediction software have been tested also in a scale model. With reference to a typical urban configuration, results are expressed as level difference between the simple plane façade and the façade with different kind of shielding. [ABSTRACT FROM AUTHOR]

The article focuses on Regupol 6010BA from CMS Acoustic Solutions, a high performance acoustic system with superior performance in sound insulation that will be installed at One Hyde Park in London, England. The Regupol 6010BA will be installed in areas where stone or marble floor finish will be used due to its feature of controlling impact sound. The product is also resistant to deformation and ageing, providing lifetime sound insulation.

An abstract of the article "Determination of Measurement Uncertainties in Building Acoustics by Interlaboratory Tests. Part 1: Airborne Sound Insulation" by V. Wittstock and colleagues is presented.

An abstract of the article "Characterisation of an Elastomer for Noise and Vibration Insulation in Lightweight Timber Buildings" by J. Negreira and colleagues is presented.

An abstract of the article "Correlation Between Sound Insulation and Occupants' Perception-Proposal of Alternative Single Number Rating of Impact Sound," by F. Ljunggren and colleagues is presented.

The article reports on the renewed calls for a noise barrier to be installed near worst affected areas of Emmbrook in Berkshire, England, relative to plans to spend over £600 million for the planned Smart Motorway congestion-reduction scheme. The use of hard shoulder could raise the burned on neighbouring families and residents according to Paul Gallagher, chairman of Emmbrook Residents' Association.

An abstract of the article "Acoustic Behavior of High Acoustic Performance Window Glazing" by D. Mateus is presented.

An abstract to the article "The Position of the Instruments for the Sound Insulation Measurement of Building Facades: From ISO 140-5 to ISO 16283-3," is presented.

An abstract of the article "A Comparison of Measurement Standard Methods for the Sound Insulation of Building Facades," by U. Berardi is presented.

The article reports that the Institute of Acoustics (IOA) is launching a five-day short course in building acoustics measurements and sound insulation in spring 2012.

The article reports on a study which examines the use of a reduced size acoustic chamber to analyze the impact noise reduction, limitations, and applicability provided by different types of floor coverings.

Lightweight building systems in general suffer from poor sound insulation, especially in the low frequency region. Since no reliable mathematical models that can predict the impact sound pressure level exists, the lightweight building design is to a high extent based upon previous experience and upon measurements. A special difficulty is related to experimental measurements since the variation among identical units must not be neglected. A modern volume based lightweight wooden building concept has here been tested by numerous well controlled measurements, in laboratory as well as in more field like conditions. The volume construction technique offers new possibilities and challenges to improve sound insulation in light weight timber construction. The main purpose was to investigate how different constructional solutions in the floor , like plaster board, mineral wool, elastic glue, dividing board, floating floor etc., affect the sound insulation. Many of the tested modifications resulted in only marginally changed impact sound pressure level but parameters that substantially can improve the sound insulation were found in using elastic glue to mount the floor boards, to install extra board layers and to use floating floors. [ABSTRACT FROM AUTHOR]

Noise-induced hearing loss is almost always preventable if properly fitted hearing protectors are worn to reduce exposure. Many individuals choose not to wear hearing protection because it may interfere with effective communications in the workplace or it may be uncomfortable. Hearing protector comfort has not received the same amount of attention as noise reduction capability. The present study was conducted to evaluate the comfort level of two different types of insert earplugs as well as the attenuation levels achieved by the earplugs. Attenuation levels were obtained with a commercially available earplug fit-test system, and the comfort ratings were obtained by questionnaire. The primary model provided evidence for an inverse relationship between comfort and attenuation. [ABSTRACT FROM AUTHOR]

The context of the present paper is the wall treatment of flow ducts, notably aero-engine nacelle intakes and outlets. For this purpose, hybrid active/passive absorbers have been developed at the LMFA for about 15 years. A hybrid cell combines passive absorbent properties of a porous layer and active control at its rear face. Active control is mainly used to increase absorption at low frequencies by cancelling the imaginary part of the surface impedance presented by the absorber. However, the optimal impedance (i.e. the one that produces the highest noise reduction) of an absorber for flow duct applications is generally complex and frequency dependent. A new hybrid absorber intended to realise any of impedance has therefore been developed. The new cell uses one microphone on each side of a resistive cloth. Normal velocity can then be deduced by a simple pressure difference, which allows an estimation of the surface impedance of the absorber. In order to obtain an error signal related to a target impedance, the target impedance has to be reproduced in time domain. The design of a stable and causal filter is a difficult task, considering the kind of frequency response sought. An alternative way of representing the impedance in time domain is therefore given. The new error signal is integrated into a feedback control structure. Fast convergence and good stability are observed for a wide range of target impedances. Typical optimal impedances with a positive increasing real part and a negative decreasing imaginary part have been successfully realised. Measurements in a grazing-incidence tube show that the new complex impedance absorber clearly outperforms the former active absorber. [ABSTRACT FROM AUTHOR]

As effective, low-cost isolators, resilient bars have become the dominant ceiling treatment for improving the sound insulation of apartment timber floors in the UK to meet increasingly stringent building regulations. There are many variations on the resilient bar theme available on the market, many differing only in their detailed features. Their acoustic performances are not however, consistent. This research investigated the isolating effects of resilient bars from four perspectives: that of their rotational resilience when acting as a spring hinge, considering their base flange as a spring, their ceiling flange as a spring and examining the spring effect provided by the bar in its longitudinal direction. Two types of experiment were designed: vibration transmission tests on a small-scale timber floor model, and static stiffness tests on small resilient bar specimens. Data revealed the relative importance of key features while providing improved design guidance. [ABSTRACT FROM AUTHOR]

Many European countries have a sound classification standard connected to the building regulations in order to specify minimum requirements. The various national standards have a lot of similarities, however the acoustic descriptors differ more than what is obvious by a quick comparison of current classification standards. The different descriptors in each country are to some extent a heritage from the past, successively adapted to the building industry in each country and their certain traditions in building technique. The descriptors and the requirements are necessarily not based on subjective experience. Furthermore, to fulfil national interests and to fit to new design trends of housing units etc., the descriptors involve small local adaptions to each country. These local adaptations are not easy to find unless the standards are read carefully. This causes problem since the building industry is not restricted to national boundaries anymore. Many companies have activity in countries adjacent to each other and in future the probability for increased activity all across Europe and also outside Europe is to be expected, unless regulations restrict this development. Combining national special rules and some severe uncertainties in the measurement and evaluation procedures of sound insulation, the situation is more critical for lightweight structures. This is partly due to the fact that the development of building systems are made in one country, the production takes place in production plants, i.e. the production and the process are fitted to local regulations and are "standardized". The standardized process is fast and dry but also needed due to lack of prediction models. And once the light weight system and the system process are established in one country it is complicated and expensive to adapt them to other countries. In this paper an overview of special national rules in some European countries and major problems connected to lightweight construction are presented. [ABSTRACT FROM AUTHOR]

The article reports on a statement issued by Australian Federal Transport Minister Anthony Albanese that the decision of the Australian government not to fund insulation for homes near the airport in Perth is based on scientific forecasts.

The article reports on the issuance of a contract amounting to over one million dollars to soundproof 69 residences in a program that involves Los Angeles International Airport in California.

An abstract of the study "Sound Propagation in Soundproofing Casement Windows," by N. Yuya et al, published in a 2009 issue of the journal "Applied Acoustics" is presented.

The article focuses on a study which analyses various models for prediction of airborne sound insulation of multi-layer materials with viscoelastic thin sheets. It references a study by A. Jesús published in a 2008 issue of "Building Acoustics." It notes that the prediction models are based on several hypothesis such as adaptation of impedances, spatial behaviour of spectral components and the Finite Element Method (FEM). There are proposed adjustments to the models to improve the prediction in some frequency ranges.

The article focuses on the sound proofing requirements directed to music venues in Cardiff, Wales. The Globe, which opened in November 2008, has to undergo remedial sound work months after its opening as the city council has issued a noise abatement notice for it. It adds that Point in Butetown has been forced into foreclosure in May 2009 as a result of the costs it incurred from insulation, revenue loss while sound work was being conducted and existing trading conditions.

The article reports on the near completion of a programme that buys, demolishes and insulates houses near the Indianapolis International Airport by the Indianapolis Airport Authority in Indiana. The agency has purchased nearly 1,200 houses, farms and other properties and demolished houses in areas with the highest noise. It also insulated 183 houses for free. The agency bought another 115 to be insulated and resold.

The article announces Toyota's installation of new Active Noise Control Technology inside the Toyota Crown Hybrid. The system uses three microphones to listen for noise inside the car, then passes it to a processor that flips it and plays reversed signals out of three speakers in the front door and parcel shelf. The system is said to reduce noise from the engine, road, and other cars by up to 8 dB.

The article reports on the plan of Shanghai, China to install more noise-insulation screens on elevated roads in 2008.Cai Yifeng, senior engineer of Shanghai Transportation Planning Institute, cites the importance of tackling noise pollution as the city develops rapidly. The noise will be reduced by the new screens for the increasing number of residential highrises that are being built along the elevated roads.

The article reports on the results from a 2007 Canadian Language and Literacy Research Network study that found that many classrooms had poor acoustics and that students were usually working in below standard classroom listening conditions. According to the study, the average Grade 1 student cannot understand one in six words due to excessive background noise and poor acoustics in classrooms in Canada.