sound absorbing Articles

  • Acoustical characterisation of porous sound absorbing materials: a review

    Over the past 50 years, the characterisation of porous sound absorbing materials has been of increasing interest to both the acoustic engineers and customers. It is particularly important that acoustic engineers are able to predict the acoustical behaviour of these materials to get a quantitative measure of the acoustic energy absorption. This paper reviews the relevant literatures over this ...


    By Inderscience Publishers

  • Tackling Office Noise – The Sound Investment

    Open offices or shared offices can offer great benefits in terms of communication but they can also present challenges. We’ve all had problems with noise in the office - the incessant chatter of your colleagues ruining your concentration; people shouting over you when you are trying to have a conversation on the phone; perhaps even maintenance or construction work going on next door. ...


    By Pulsar Instruments plc

  • Elastic sound absorption theory of fibrous material

    Because of the complexity of classical sound absorption theory's expressions, it is difficult to obtain physical insight into the acoustic behaviour of porous materials and to determine the dominant mechanism for sound absorption for a given material at a given frequency. Alternatively, there are very simple expressions. A new theory has been put forward that fibrous material absorbs sound by the ...


    By Inderscience Publishers

  • Sound field diffusivity at the top surface of schroeder diffuser barriers

    It has been shown in several studies that the T-shape profile barriers are one of the most successful noise barriers among many different profiles (May and Osman 1980; Hajek and Blaney 1984; Hothersall et al., 1991). In this case, it is shown by author (Monazzam and Lam, 2005) that in the same dimension, the T-shape profile has the highest performance compared to other profiled noise barriers. It ...


    By University of Tehran

  • 50th anniversary of world`s first sound level meter

    Sound Level Meter Celebrates 50th Anniversary 2010 is the year we celebrate the 50th anniversary of Type 2203, the mother of all sound level meters. It was the world’s first precision hand-held and transitorised sound level meter. Produced for 21 years, it sold a record number of 17300 units. With its upgrades Type 2204 (Impulse time constant) and 2209 (peak detector), it accounted for a ...

  • Dissipative expansion chambers with two concentric layers of fibrous material

    The acoustic performance of a dissipative expansion chamber lined with two concentric, annular layers of fibrous material with different resistances is investigated. A two-dimensional analytical approach is used to determine the transmission loss of this dissipative silencer. From the boundary conditions at the rigid wall, and the interfaces between the fibre layers and the central airway, the ...


    By Inderscience Publishers

  • Sarakasi Theatre - room acoustical measurements and modelling

    Measuring Reverberation Time and Speech Intelligibility using Balloons and an MP3 Player as External Sound Sources The non-profit organisation Sarakasi Trust owns a theatre in Nairobi Kenya, inside the former Shan Cinema. In this theatre, youths from the city slums are trained to be acrobats, so that they learn how to make a living without having to resort to crime. Shows and concerts are ...

  • Acoustiblok® Quiets Well Motor Noise for California Water District

    Acoustiblok recently resolved a noisy well motor issue that was affecting some nearby residents for Three Valleys Municipal Water District (Three Valleys MWD) in California. Ben Peralta, a Three Valleys MWD engineer working on the project said, “The new Acoustiblok All Weather Sound Panels perform better than the old ...


    By Acoustiblok International

  • Reducing noise levels through engineering controls

      It"s fairly easy to control personal exposure to noise by limiting exposure time or using hearing protectors like ear plugs or ear muffs.  Engineering controls are usually applied to the machinery that produces noise. Imagine a 200 foot x 175 foot manufacturing facility with a 30 foot high ceiling.  In this building are a variety of cut-off saws, grinders, millers and other ...

  • Active leakage control in low pressures - It can be done!

    Leakage and PressureWater when leaving the pipe creates an ‘energy’ and it is this energy that is transferred through the water and the pipe wall by the means of acoustic sound. This acoustic sound depending on the material of the pipe work either dissipates over a long distance or is absorbed very quickly into the pipe wall. The effect being that for metallic or hard walled pipes the sound ...


  • Infrastructure asset management – the TRUST approach and professional tools

    Strategic asset management (AM) of urban water infrastructures faces the challenge of dealing with expensive and long-lasting assets of a very diverse nature and wide-ranging useful lives and costs. Typically, utility managers inherit an infrastructure with assets in assorted conditions and stages in their lifecycle. They are expected to manage their value in order to ensure adequate service, ...


    By IWA Publishing

  • Accurate and efficient prediction of acoustical performance of noise barriers against transport noise pollution

    An improved acoustical wave propagator (I_AWP) technique with high-order absorbing boundary technique is introduced to evaluate the acoustical wave interaction for noise barriers, providing the dual benefit of preserving high numerical accuracy (boundary conditions have been properly treated) and obtaining high computational efficiency (using a larger time step in the calculation). The aim is to ...


    By Inderscience Publishers

  • Connections: Understanding Urban Soil Lead

    There is no such thing as unleaded when talking about soils in urban areas. If a car had ever been driven near or paint had been applied to a home built on the soil prior to 1975, that soil will have measurable concentrations of lead. It can be detected in soils at the subparts per million range. Lead can cause developmental delays and reduced mental capacity. In short, lead is bad. But does a ...


    By BioCycle Magazine

  • What is an anechoic chamber and how quiet can it be?

    One of the things that we often talk about when we’re running our CPTC (Cirrus Product Training Courses) is how our hearing works and we often end up talking about how, if there’s no ambient sound, we can feel uncomfortable and can become disoriented very quickly. One of the best (or maybe the worst) places to experience this is in ...


    By Cirrus Research plc

  • Measuring level by weight

    Measuring level or inventory by weight provides high accuracy. The weight is not affected by ingredients that foam or settle unevenly or by changes in density or the shape of the tank. Weight is weight, regardless of percent solids, bridging, rat-holing, or whether your ingredient is conductive or sound-absorbing. Because weighing is a noncontact method of measuring level, there is no chance of ...


    By Hardy Process Solutions

  • The role of foreign direct investment in Indonesia's industrial technology development

    Despite the large inflows of FDI into Indonesia's manufacturing sector during the past three decades, Indonesia has in general not been very successful in taking full advantage of the presence of FDI projects to promote the development of its indigenous industrial technological capabilities, at least compared to its East Asian neighbours. This lack of success has been attributed to the high ...


    By Inderscience Publishers

  • Exchange of Transformers in the castle and in the city of Marburg

    The challenge for the team of ABB Environmental Services, led by Helmut Bergel, was a full service project, including the exchange and replacement of transformers contaminated with the environmental pollutant PCB (Polychlorinated Biphenyls, a class of chlorinated hydrocarbons that have been used extensively since 1960 for a variety of industrial uses like coolants in transformers and dielectrics ...

  • Blending process in everyday life

    Liquids mixing processes are extensively relates to human life. For example we could meet these processes in the laboratory chaotic advection researches, in oil processing branches, chemical, industrial and even in the food industry. Passing speed, quality of a compound and expense of energy are undoubtedly one of defining factors in developing process of compounding system. Despite that ...


    By GlobeCore GmbH

  • Blending process in everyday life

    Liquids mixing processes are extensively relates to human life. For example we could meet these processes in the laboratory chaotic advection researches, in oil processing branches, chemical, industrial and even in the food industry. Passing speed, quality of a compound and expense of energy are undoubtedly one of defining factors in developing process of compounding system. Despite that ...


    By GlobeCore GmbH

  • Using Coir Geotextiles for soil erosion control

    One of the most effective and yet natural soil erosion prevention techniques is the use of Coir Geotextiles fabrics ( Woven Geotextiles). Used extensively to prevent environmental degradation Geotextiles have no synthetic material but is instead made out of an organic fiber, coir, which is extracted from the husk of a coconut. It is strong, durable, water proof and is one of the few natural ...


    By CoirGreen

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