sound attenuation Articles

  • Impact of sound attenuation by suspended sediment on ADCP backscatter calibrations

    Abstract. Although designed for velocity measurements, acoustic Doppler current profilers (ADCPs) are widely being used to monitor suspended particulate matter in rivers and in marine environments. To quantify mass concentrations of suspended matter, ADCP backscatter is generally calibrated with in situ measurements. ADCP backscatter calibrations are often highly site-specific and season ...


    By Teledyne RD Instruments

  • DuPont LoWave Acoustic Material with Low-Frequency attenuation case study

    A major U.S. manufacturer of laboratory equipment was concerned that one of its newest pieces of equipment would not gain widespread acceptance in the marketplace due to its high overall noise level and unpleasant sound quality. Company officials needed to improve the sound signature of the equipment improving the comfort level of people working around it, without altering product design in a way ...


    By NEVA Associates

  • The Investigation of Noise Attenuation by Plants and the Corresponding Noise-Reducing Spectrum

    As noise pollution is becoming more and more serious, many researchers are studying the noise attenuation effect provided by plants. This article examines six kinds of evergreens as research subjects so as to compare the different arrangements and densities of plants and their effect on noise attenuation. The authors studied the relationship between each of the plant’s characteristics (the ...

  • Vinyl Chloride Attenuation By Direct Injection of Time-Release Magnesium Peroxide.

    ABSTRACT: This case study shows that there is potential to remediate dissolved vinyl chloride by oxygenation in the field. Residual vinyl chloride concentrations have been remediated in the field at a mid-western site with a phosphate-intercalated peroxygen (ORC®, a proprietary formulation of magnesium peroxide that releases oxygen slowly). The site was formerly operated as an aluminum coating ...


    By REGENESIS

  • Sound treatment and structural optimisation for acoustic performance of front dash with sound contribution

    Dash of the vehicle poses an important role in attenuating the sound radiated from the engine cabin. The acoustical performance of a vehicle dash system is determined by the sound transmission loss (STL). Computational modelling of such system poses challenge due to the complexity of the material properties as well as geometry. In the analysis, a numerical method with structure–sound interaction ...


    By Inderscience Publishers

  • A computational–efficient active sound tuning system for steady–state and transient vehicle powertrain response

    Conventional vehicle active noise control (ANC) methods aimed mainly at attenuating the cabin interior noise usually do not account for sound quality effects. In this paper, an active sound tuning (AST) system is proposed to reshape the vehicle powertrain response based on the predetermined vehicle interior sound quality criteria. Since it is important to develop a computational–efficient ...


    By Inderscience Publishers

  • 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

  • Evaluation of xenobiotic impact on urban receiving waters by means of statistical methods

    Xenobiotics in urban receiving waters are an emerging problem. A sound knowledge of xenobiotic input, distribution and fate in the aquatic environment is a prerequisite for risk assessments. Methods to assess the impact of xenobiotics on urban receiving waters should address the diverse characteristics of the target compounds and the spatiotemporal variability of concentrations. Here, we present ...


    By IWA Publishing

  • ‘Kyoto cost’ of various production and recycling processes

    ‘Kyoto cost' of various production and recycling processes: An interesting take on the the total CO2 emissions released during the lifetime of various containers used in the manufacturing and delivery of bottled water and other fluid products typically consumed in North America ...


    By Baum Publications Ltd.

  • Ask Yourself These Questions Before You Buy a Granulator

    Ask Yourself These Questions Before You Buy a Granulator 1 WHAT DO YOU WANT TO GRIND? * Consider: Type of part or sprue/runner system, type of material (hard/soft, brittle/tough, filled/unfilled), and temperature of parts being granulated. * Determines: Rotor design, horsepower, sound attenuation, ...


    By Harden Industries Ltd.

  • Characterisation of adaptive filters used in the identification process of annoying noises in vehicles

    To identify annoying noises (squeaks and rattles) inside vehicle cabins, it is necessary to capture the sounds present inside them and eliminate or attenuate all external noises from the obtained signal by using LMS, RLS or Kalman adaptive filters. This work aims to characterise the performance of these filters and select the one most suitable for this application. Analytical and experimental ...


    By Inderscience Publishers

  • Two Technologies for Flow Measurement from Outside a Pipe

    Doppler and Transit Time are two very popular types of flow meter for non-invasive measurement of flow in full pipes. We tend to confuse these technologies because they are both ultrasonic and both measure flow by using sensors clamped onto the outside of a pipe. In the real world they actually work best in opposite applications. Success in your installation depends on understanding the ...


    By Greyline Instruments Inc.

  • Surprised by a police siren?

    Simulating Sirens Researchers at Canada's University of Windsor Sound Quality lab are using the Brüel & Kjær NVH Driving Simulator to determine whether a new type of police siren will better alert drivers to approaching police vehicles and save lives in the process. The Rumbler   The new siren is called a Rumbler and emits a ...

  • How the LISST-ABS works

    INTRODUCTION: Sequoia’s Acoustic Backscatter Sensor, LISST-ABS is designed to measure suspended sediment concentration at a point. Unlike ADCP’s which may record similar backscatter strength at multiple points along the acoustic beams (‘ranges’), the LISST-ABS  only reports backscatter signal strength at a single point about 5 cm from the transducer. The ...


    By Sequoia Scientific, Inc.

  • Environmental Noise

    Introduction The ability to hear sounds is a sensory function vital for human survival and communication. However, not all sounds are wanted. 'Unwanted sounds', for which the term 'noise' is normally used, often have their origin in human activities (mainly transport, industry and households). This article addresses environmental noise ­ also referred to in the scientific literature as ...

  • Oil Mist Collectors: Installation Costs

    An oil mist collector not only protects the health of employees, but also makes an addition to your machining equipment. These are inexpensive pieces of equipment and installing the system doesn’t require any high costs. However, there are a few costs that arise after installation, which all companies with this system will face. Equipment Downtime Depending on how the oil ...


    By ProVent, LLC

  • UWB Subsurface Radar With Antenna Array for Imaging Of Internal Structure Of Concrete Structural Elements

    Introduction The basic design principals implemented in the advanced UWB radar with time-domain operation and with the 100 - 900 MHz effective band are considered including real synthetic array and full-polarimetric schema. The radar is installing on a moveable platform for remote operation on the territories with radioactive pollution. This probing system should be employed near the nuclear ...


    By Transient Technologies LLC

  • Noise Measurement

    Definitions Threshold and criterion levels The threshold level is the A-weighted sound level at which a personal noise dosimeter begins to integrate noise into a measured exposure. For example, if the threshold level on a sound level meter is set at 80 decibels (dB), it will capture and integrate into the computation of dose all noise in the employee's hearing zone that equals or exceeds 80 dB. ...


  • Case No. 501: New QXC Silencer/Converter Installed on Waukesha H24GSID 375 KW Natural Gas Engines Achieves 2007 California NOx Regs

    Generating power with natural gas engines in large commercial buildings, while controlling emissions and noise from the engines requires a unique catalytic solution. Johnson Matthey’s new QXC model 3-Way converter silencer was chosen for the task. This design contains a unique catalyst element sealing system ...

  • GKN aerospace success with portable impedance meter

    The GKN site in Cowes, Isle of Wight, UK, has long experience in the design and manufacture of passive sound insulation systems for air-intakes and by-pass ducts of aircraft engine nacelles. Dr. Armando Vavalle, Technology Development Engineer from GKN reports here on impedance tests conducted with Brüel &Kjær’s Portable Impedance Meter Type 9737 for the development of such ...

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