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    Noise Control Engineering Journal

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    Mar 2012

    Volume 60, Issue 2, pp. 125-223


    Mitigation of noise emissions from vehicles passing bridge expansion joints

    Klaus-Peter Glaeser, Gernot Schwalbe, and Marek Zöller

    Noise Control Eng. J. 60, 2, pp. 125-131 (2012)

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    In the German project ‘silent road traffic 2’ a special sub-project for bridge expansion joint noise mitigation was launched. Travelling over a standard modular bridge expansion joint (lamella joint) with a vehicle creates a short noise impulse. The noise is the result of the vehicle’s tyres striking the rectangular face of the expansion joint units and traversing the discontinuous surface profile. This noise can be annoying for those residing near the bridge. A reduction of the noise emission can be achieved by mounting noise reduction elements on top of the transition segments, by creating an even surface for the tyre to traverse, and still allowing the joint to contract or elongate as required due to the influence of seasonal temperature variation. Different surface elements for covering the transition segments with varying shapes and surface textures were tested in the tyre-road-interaction test-facility (PFF) of BASt. The surface elements had different shapes and surface characteristics; five were of a rhomboidal shape with three profile angles, one was ‘mushroom’ shaped, and two were of a sinusoidal shape. The surface elements were provided by two German manufacturers. The noises emission caused by traversing of a standard passenger car tyre was investigated for different velocities. All tests were carried out with two different spacings representing summer and winter position. It was found that a noise reduction of up to 9 dB could be achieved, when compared to conventional surface elements.
    Show PACS
    43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles
    43.40.-r Structural acoustics and vibration
    43.50.Pn Impulse noise and noise due to impact
    43.50.Gf Noise control at source: redesign, application of absorptive materials and reactive elements, mufflers, noise silencers, noise barriers, and attenuators, etc.

    Influence of honking on the noisier situation (L10)

    T. K. Roy, A. R. Mukhopadhyay, S. K. Ghosh, and G. Majumder

    Noise Control Eng. J. 60, 2, pp. 132-136 (2012)

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    A study of noise due to honking and its impact on L10 has been carried out at Kolkata metropolis. The relation between L10, honking, traffic and the percentage of heavy vehicle has been determined. L10, the noise level that exceeds 10% of the monitoring time, is a measure of the higher noise level. In this paper, regression equation between L10, honking, traffic and the percentage of heavy vehicle has been developed for the prediction of L10. The same equation can be used for reducing L10 by exercising appropriate control over the suitable predictor(s). The article also delineates as to what kind of control is called for reducing L10.
    Show PACS
    43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles

    Application of the equivalent source method to directional noise sources

    Sergey N. Vecherin, D. Keith Wilson, and Vladimir E. Ostashev

    Noise Control Eng. J. 60, 2, pp. 137-147 (2012)

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    Prediction of noise levels at long ranges from such sources as flying aircraft or moving ground vehicles is an important practical problem. When terrain, wind, and atmospheric effects are taken into account, this problem cannot be solved analytically, and, thus, numerical solutions are required. There are several numerically efficient algorithms to solve the problem, but, typically, all of them are designed for an omnidirectional point source. Such specification is inadequate for complex and extended sources exhibiting directional radiation patterns. Thus, a method for incorporating directional sound sources into propagation algorithms is needed. This paper describes the equivalent source method (ESM), which enables reconstruction of a compact point-source distribution reproducing a given, arbitrarily complicated, radiation pattern in the far field. The ESM is demonstrated using an asymmetrical surrogate aircraft radiation pattern. Application of the ESM to parabolic equation algorithms is also considered. Some issues of acquisition of input data, such as outliers and data incompleteness, and their adverse effect on source reconstruction are also discussed.
    Show PACS
    43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles
    43.28.Hr Outdoor sound sources
    43.25.Ts Nonlinear acoustical and dynamical systems
    43.50.Yw Instrumentation and techniques for noise measurement and analysis
    43.50.Ba Noisiness: rating methods and criteria
    43.50.Rq Environmental noise, measurement, analysis, statistical characteristics

    Generation of impulsive sound with speakers

    Clement Blanc, Marcel C. Remillieux, Joseph M. Corcoran, and Ricardo A. Burdisso

    Noise Control Eng. J. 60, 2, pp. 148-157 (2012)

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    This paper presents a time-domain, wave-decomposition method for generating impulsive sound of a relatively general time dependence (e.g. N-waves), using an array of speakers. The objective of this work is to develop a simulator that could provide pressure loading to building structures: to validate vibro-acoustic models or to conduct subjective studies on human response to impulsive sound. When playing impulsive sound through a speaker, the dynamics of the physical system (e.g. speakers and amplifiers) and scattering of sound in the environment (e.g. ground reflection and edge diffraction) are such that the time history of the pressure recorded by a microphone installed on the structure will not be the original input signal, but a distorted version of it. Using this distorted microphone signal, the input signals to an array of speakers can be pre-distorted to recreate the desired waveform on the structure. A wave-decomposition method is used for this purpose. The formulation is derived in a very general fashion, for an array of Ns speakers and using the signals of Nm microphones. The method is validated experimentally using successively 1 speaker and 1 microphone, 1 speaker and 2 microphones, 2 speakers and 5 microphones.
    Show PACS
    43.50.Pn Impulse noise and noise due to impact
    43.38.Kb Microphones and their calibration
    43.40.-r Structural acoustics and vibration

    Four-pole modelling of vibration isolators: Application to SEA of aircraft double-wall panels subjected to mechanical excitation

    B. Campolina, N. Atalla, N. Dauchez, and P. Neple

    Noise Control Eng. J. 60, 2, pp. 158-170 (2012)

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    This paper aims at determining the structural coupling loss factor (CLF) between two plates connected via vibration isolators, using a four-pole approach. A hybrid Experimental-SEA (statistical energy analysis) model has been developed for predictions and two configurations are analysed. Configuration 1 is composed of two isotropic plates with critical frequencies around 3750 Hz and 6000 Hz. Configuration 2, more representative of an aircraft fuselage, is composed of a stiffened isotropic plate and a sandwich panel. Plates are coupled at 6 locations via elastomeric mounts. They are mechanically excited by a point force at random positions in the 100 to 10000 Hz frequency range. The modelling of the isolators integrates their frequency dependent measured stiffness. Four configurations are compared for the stiffness measurement and the most adapted setup is derived. The modelled CLFs are then compared with measurements using an experimental SEA approach. Finally, the space-averaged quadratic velocities of the plates are calculated using the hybrid model and compared with experiments. Results show a good correlation between predicted and measured CLFs but further refinement is needed in order to account for radiation coupling near the critical frequencies of the plates.
    Show PACS
    43.40.Tm Vibration isolators, attenuators, and dampers
    43.40.At Experimental and theoretical studies of vibrating systems
    43.40.Dx Vibrations of membranes and plates

    Relating the near field noise of passenger cars with the driving behavior

    D. Ibarra, P. Cobo, J. A. Calvo, and J. L. San Román

    Noise Control Eng. J. 60, 2, pp. 171-183 (2012)

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    Road traffic noise amounts to roughly half of the overall ambient noise. Usual emission (vehicle emission limits) and immission (barriers, sound-reducing windows) noise control techniques have not been enough to decrease significantly the annoyance by road traffic over the last three decades. The positive effect of these control techniques has been counteracted by the increase of traffic density. Moreover, the traffic noise annoyance is highly correlated with the maximum noise levels usually produced by aggressive drivers. However, current traffic noise measurement systems are based upon an overall assessment, so that they are unable to discriminate between quiet and noisy drivers. Therefore, a near field noise measuring system is proposed in this paper that is able to measure the contribution of each vehicle to the road traffic noise, allowing the detection of noisy drivers. The system is based on two onboard microphones, one for the engine noise and other for the rolling noise. Experimental results are provided that demonstrate the performance of the proposed system on five drivers, along suburban and urban courses of a large city, with petrol and diesel vehicles. The analysis of concurrent acoustical and driving condition data reveals that the system is capable of discriminating clearly those vehicles generating the maximum noise levels.
    Show PACS
    43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles
    43.50.Qp Effects of noise on man and society
    43.50.Rq Environmental noise, measurement, analysis, statistical characteristics
    43.50.Yw Instrumentation and techniques for noise measurement and analysis

    Sound insulation performance of prefabricated cabins in cruise ships

    Sang-Ryul Kim, Hyun-Sil Kim, Jae-Seung Kim, Bong-Ki Kim, and Seong-Hyun Lee

    Noise Control Eng. J. 60, 2, pp. 184-191 (2012)

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    In this paper, sound insulation performance of a prefabricated cabin mock-up is studied. The cabin mock-up consists of two identical rooms whose partition, ceiling, and side walls are sandwich panels composed of thin metal sheets and mineral wools. The floor is a steel plate with stiffeners, and plate thickness is 6 mm. It is shown that sealing gap between the floor and the partition improves STL (Sound Transmission Loss) significantly above 2000 Hz. Even after all gaps are sealed, the weighted sound reduction index Rw of the partition measured in the mock-up is lower than that from laboratory measurement by 9 dB. To find out how flanking transmission of noise degrades Rw of the partition, we measure structure-borne noise (SBN) of room surfaces. It is found that SBN of the steel floor is the most important factor in flanking transmission of SBN. Although SBNs of sandwich panels in the source room are larger than that of the floor, they decrease rapidly as they propagate to the receiving room, because sandwich panels provide considerably more damping than the steel floor. Consequently, SBN of the floor becomes dominant in the receiving room. Statistical energy analysis is performed, where SBN transmission along the floor is investigated. It is concluded that that the most effective way to reduce flanking transmission of SBN is to increase damping of the floor.
    Show PACS
    43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
    43.50.-x Noise: its effects and control

    Simulations and measurements on muzzle blast mitigation with sound absorbing barriers

    Frits J.M. van der Eerden and Frank H.A. van den Berg

    Noise Control Eng. J. 60, 2, pp. 192-201 (2012)

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    Environmental research is ongoing to predict and to mitigate the noise impact of heavy weapons or explosives. In the densely populated area of the Netherlands this is of particular interest for the Ministry of Defence as the shock waves can propagate over large distances. In this research program the mitigation of shock waves by means of a sound absorbing barrier close to the source has been investigated and tested. The sound propagation and the interaction with a barrier close to the source is non-linear. In this region, a so-called FCT model is used to describe the non-linear phenomena. It is demonstrated and validated that a better shielding of strong shock waves can be obtained by adding absorbing material to the barrier. To predict the sound immission at larger distances the shock waves are propagated further (linearly) with a PE model.
    Show PACS
    43.50.Fe Noise masking systems
    43.50.Gf Noise control at source: redesign, application of absorptive materials and reactive elements, mufflers, noise silencers, noise barriers, and attenuators, etc.
    43.50.Pn Impulse noise and noise due to impact

    Field investigation of the effects of vegetation on the performance of roadside noise barriers

    Shira Daltrop, Murray Hodgson, and Clair Wakefield

    Noise Control Eng. J. 60, 2, pp. 202-208 (2012)

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    The effects of nearby foliage on the performance of noise barriers are not well established. Foliage may decrease noise levels behind a barrier, either by back-scattering or absorbing sound. Foliage may also increase noise levels by scattering sound which would normally pass above the barrier into the shadow zone. Field test sites were identified to study these effects. Traffic noise levels were measured simultaneously behind foliage and no-foliage configurations and the results compared. Both increased and decreased noise levels behind the barrier were seen, with most effects being less than 5 dB.
    Show PACS
    43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles
    43.50.Rq Environmental noise, measurement, analysis, statistical characteristics
    43.58.Fm Sound level meters, level recorders, sound pressure, particle velocity, and sound intensity measurements, meters, and controllers
    43.20.Fn Scattering of acoustic waves

    Flow-generated tones inside and outside mufflers with expansion chambers

    Jiang Du and Hua Ouyang

    Noise Control Eng. J. 60, 2, pp. 209-219 (2012)

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    Detailed experiments are conducted to investigate flow-generated tones inside and outside mufflers with expansion chambers. Three types of tones are captured inside and outside the mufflers. The first type of tones is captured both inside and outside the mufflers with three length-to-diameter ratios (L/D). They are generated by tailpipe resonances and can be predicted accurately by the natural acoustic mode frequencies of tailpipe. The second type of tones is captured both inside and outside the muffler at medium values of L/D but only inside at large values of L/D. These types of tones are induced by the chamber resonance of the muffler and agree with the natural acoustic mode frequencies of the chamber inside the muffler. These tones are captured only inside the muffler at small and medium values of L/D and are closely related to a complex flow-acoustic feedback loop inside the muffler. Moreover, the tailpipe works like an acoustic filter which influences the sound pressure levels (SPL) outside the muffler.
    Show PACS
    43.50.Ed Noise generation
    43.58.Kr Spectrum and frequency analyzers and filters; acoustical and electrical oscillographs; photoacoustic spectrometers; acoustical delay lines and resonators

    Auditory and Visual Sensations

    Yoichi Ando, Peter Ceriani, and David Lloyd (ben Yaacov Yehuda) Klepper

    Noise Control Eng. J. 60, 2, pp. 220-221 (2012)

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    Abstract Unavailable
    Show PACS
    01.30.mm Textbooks for graduates and researchers
    43.64.-q Physiological acoustics
    43.66.-x Psychological acoustics
    87.19.lt Sensory systems: visual, auditory, tactile, taste, and olfaction

    Aircraft Noise Assessment, Prediction and Control

    Oleksandr Zaporozhets, Vadim Tokarev, Keith Attenborough, and Nicholas P. Miller

    Noise Control Eng. J. 60, 2, pp. 222-223 (2012)

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    Abstract Unavailable
    Show PACS
    01.30.Vv Book reviews
    43.50.-x Noise: its effects and control
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