bluuebunny/crossref_metadata_2025 huggingface dataset:
A study of the effectiveness of the key environmental protection policies for road traffic noise control
Authors: Zhang Jiping , Schomer Paul D. , Yeung Maurice , Zhou Anguo , Ming Hui , Chai Juan , Sun Lu
Published: April 2012

This paper introduces the history and current status of key environmental policies implemented for road traffic noise control in China, based in part on lessons learned both from international experiences and from China's own experiences. The general framework for traffic noise control in China is similar to what can be found in many foreign countries, and it has been playing an important role in environmental management of the rapidly-growing Chinese economy. The key international environmental policies for road traffic noise control in developed countries are very mature from the technological, economic, legal, and sociological standpoint, and these policies indicate a sharp conflict between road traffic noise and land uses along the road for distance up to about 200m from the road. But China faces greater limitations in using and enforcing these policies to control road traffic noise completely. This paper reconsiders and evaluates China's environmental policies for road traffic noise by collecting and comparing difficult cases of road traffic noise management in other countries to the Chinese experience so as to learn from these experiences now and minimize problems for the future. The research supported from the State Key Lab. of Subtropical Building Science South China University of Technology.
Study on the legislation and management system of community noise
Authors: Chu Yiping , Zhou Yude , Zhu Wenying
Published: April 2012

Community noise is very common and numerous in urban life. According to the investigation in Shanghai, most of community noise is accidental, and its impact is different from industrial noise, traffic noise and construction noise. Measured by the one-hour or daily equivalent sound pressure level of current standard, the community noise will not exceed usually. On the other hand, based on the current Law of China on Prevention and Control of Environmental Noise Pollution, `noise pollution' consists of two factors: one is to impact some person, and the other is to exceed the standard. To this extent, most of the community noise is not `pollution'. This paper argues that the majority of complaints on community noise should be ranged to the area of social public management, and discusses the legislation and management system of community noise from following aspects: 1) collecting of the existing complaints on community noise; 2) study and investigation on domestic and overseas management system of community noise; 3) the connotative meaning of community noise' impact; 4) the position of community noise in urban management, and the management system be forwarded, including the objects of management, law-enforcing department, and the content of management, etc.
Air spring vibration isolation technology for ship propulsion engine
Authors: Lin He , Wei Xu , Changgeng Shuai
Published: April 2012

Propulsion engine (PE) is one of the most dominant noise sources of ship. Due to the imposed requirement of keeping alignment with propulsion shaft during operation, the effective vibration isolation of PE using low frequency mount is difficult to implement as is often adopted by other onboard machinery. In this paper, a low frequency air spring vibration isolation system (ASVIS) with alignment control strategy for PE is conceived and introduced. The application of ASVIS to PE presents both advantages and challenges, which are discussed detailedly in the paper, as well as the feasibility of the ASVIS concept. A systematic design method of ASVIS for PE is established, with focus on the system mechanical behavior optimization and automatic alignment control algorithm development. An ASVIS prototype is designed and manufactured using the proposed method. The performance of the prototype is tested by a series of experiments, including alignment control precision and isolation efficiency. Experimental results show that using ASVIS, the vibration of PE can be attenuated to a satisfactory level, with the alignment between PE and shaft being maintained in the safe range.
A method for predicting the vibrations of underwater cylindrical shells by using the equivalent beam model
Authors: Rui Tang , Qi Li , Dejiang Shang
Published: April 2012

The vibrations of cylindrical shells with large length-to-radius radio are similar to those of beams in very low frequency band. One-dimensional beam theoretical model is only considered about the transverse displacement, neglecting the coupling effects of displacements in other directions. Only the first order beam-type modal frequency, not the other higher orders, of cylindrical shells can be predicted precisely by one-dimensional beam theoretical model. To solve this problem, an equivalent beam theoretical model is established, based on Euler-Bernoulli beam theory, in this paper. In this model, a cylindrical shell model is considered as a beam model with the same structural parameters and boundary conditions, the interaction between the structures and water is approximated to added mass. Different Young's modulus values have been searched to make the calculated results identical to those obtained by cylindrical shell theoretical model. The results show that the beam-type modal frequencies are mainly dominated by the length-to-radius radio for shells with length-to-radius radio L/a>10 and radius-to-thickness radio a/h>20, and the effect of the shell thickness to the modal frequencies can be neglected in such conditions. The equivalent Young's modulus curves for the first five order beam-type modal frequencies of cylindrical shells with different length-to-radius radio have been calculated.
Mitigation of low-frequency underwater noise generated by rotating machinery on a mobile work barge using large tethered encapsulated bubbles
Authors: Lee Kevin M. , Wochner Mark S. , Wilson Preston S.
Published: April 2012

Collections of bubbles cause significant dispersion and attenuation of underwater sound at frequencies near the individual bubble resonance and can potentially be used to mitigate low-frequency anthropogenic underwater noise. Such effects have been reported for large encapsulated bubbles with resonance frequencies below 100 Hz [J. Acoust. Soc. Am. 130:3325-3332 (2011)] and significant attenuation due to bubble resonance phenomena and acoustic impedance mismatching was observed in experiments using a compact electromechanical acoustic source [J. Acoust. Soc. Am. 128:2279 (2010); J. Acoust. Soc. Am. 129:2462 (2011)]. In the present study, screens of tethered resonant encapsulated air bubbles were used to surround a mechanically-vibrated mobile work barge in a lake experiment to demonstrate their potential as a mitigation strategy for such noise sources. Conventional screens of freely-rising bubbles were also deployed for comparison. The radiated acoustic pressure was measured at various water depths and ranges to determine the effect of the bubble screens on the noise field. Compared to the freely rising bubbles, the tethered encapsulated bubbles yielded a significant increase in noise reduction below 1 kHz, demonstrating their efficacy for abatement of low-frequency underwater rotating machinery noise. [Work supported by Shell Global Solutions.]
The acoustic and ventilation performance of new ventilated window design
Authors: Wang Michelle , Hui Catherine , Ng C.F.
Published: April 2012

Noise and air pollution problems become significantly in dense city such as Hong Kong, since buildings are usual located close to the heavy traffic lines. Traditional openable window cannot fulfill all the functions of noise reduction, lighting and natural ventilation. A new ventilated window, which combines the multiple quarter-wave resonators (silencer) with the new wing wall design, is designed to balance between acoustic and ventilation performances. Furthermore, the use of multiple-wave resonators to replace absorption material can enhance the durability; avoid small particle emission and toxic gas due to fire. The acoustic and ventilation performance of new ventilated window were examined in this study. Noise attenuation of the new ventilated window design is improved significantly by combining flexible absorber and quarter-wave resonator effects. The test methods in acoustics are in accordance with relevant ISO 140 procedures.Transmission loss of 10 dB to 22 dB can be achieved in the frequency range of 500 Hz to 4k Hz band. The best ventilation performance of the wing wall is at an incident angle of 45°. Outlet air flow velocity of ventilated window design is double of the velocity of “open window”. Thus, both the acoustics and ventilation performance of the new ventilated window is effective. Wind-driven natural ventilation is an effective way in maintaining the comfort and health of indoor environment.
Formulation and selected applications of a regularized elastodynamics integral equation approach to large scale scattering problems involving inhomogeneous objects
Authors: Bleszynski Elizabeth , Bleszynski Marek , Jaroszewicz Thomas
Published: April 2012

Elements are presented of the formulation and selected applications of the combined surface and volume integral-equation approach for finding pressure, displacement, and traction fields in composite objects consisting of piece-wise homogeneous regions characterized by different Lame's material parameters, as well as of highly inhomogeneous regions. The proposed elastodynamics surface/volume-based integral equations, in which the unknowns are volumetric pressure or displacement variables and surface displacement and traction fields on the interfaces, involve only weakly singular integral-equation kernels with at most 1/r singularity. The proposed method is found to provide well-convergent and accurate solutions for a large spectrum of problems, in particular those involving high-contrast material interfaces. The proposed method's accuracy and its capability (achieved through the (non-lossy FFT-based) Adaptive Integral Method matrix compression) of handling large-scale problems involving several millions of unknowns, is demonstrated through comparison with analytically constructed solution for a layered material sphere and in selected numerical simulations of propagation of acousto-elastic waves in human head and inner-ear region through air- and bone-conduction pathways. The proposed approach can be used in assessing effectiveness of noise-protection devices. This work is supported by a grant from the Air Force Office of Scientific Research.
Mass flow and surface wave in a vertically vibrated granular system
Authors: Cai Hui , Chen Weizhong , Miao Guoqing
Published: April 2012

We report an experimental finding on coexistence of the horizontal mass flow and the vertical surface wave in a vertically vibrated granular system. The container is an annular channel with a sawtooth-shaped base which is excited and controlled by a vibration system. The particles are copper spheres with diameter of 3 mm. The driving frequency ƒ and dimensionless acceleration amplitude Γ=4π2ƒ2Α/ɡ (Α is the driving amplitude and ɡ the gravitational acceleration) are used as two control parameters. A high-speed image recording system is used to record the movements of all spheres, and an image processing technique is used to track the locations of all particles. As Γ increases beyond a critical value (about 1.8), the granular layer fluidizes from top to lower parts, and the horizontal mass flow appears. The velocity of the mass flow increases with Γ, and from bottom to top decreases monotonously. In the meanwhile, if Γ exceeds 2.5, the vertical surface wave occurs. The amplitude of the surface wave increases with driving amplitude. The mechanism of the mass flow is the ratchet effect of the sawtooth, while the correlation between the mass flow and the surface wave is to be explored.
Reduced acoustic cloaks: theoretical analysis and numerical simulation
Authors: Fan Yuxian , Hu Wenlin , Ji Peifeng , Yang Jun
Published: April 2012

Acoustic cloaking is a new technique which can make an object invisible in acoustic waves. This method of controlling and directing sound has a promising prospect in application. Rigorous physical parameters are required for perfect cloaking, which is unpractical for experimental realization. Reduction is an alternative when imperfect cloaking performance is acceptable. In this paper, theoretical analysis of reduced acoustic cloaks based on transformation acoustics is presented. Fundamental features of acoustic cloaking are derived and discussed. Layered medium theory is employed to design reduced acoustic cloaks. Reasonable physical parameters and tolerable cloaking performance are expected in the prerequisite of the work. The properties of the designed reduced acoustic cloaks are studied. Numerical simulation shows that the reduced acoustic cloaks have effective cloaking performance.
Electrophysiologic assessment of (central) auditory processing disorder in children with non-syndromic cleft lip and/or palate
Authors: Ma Xiaoran , Ma Lian , McPherson Bradley
Published: April 2012

Cleft of the lip and/or palate is a common congenital craniofacial malformation worldwide, particularly non-syndromic cleft lip and/or palate (NSCL/P). Though middle ear deficits in this population have been universally noted in numerous studies, other auditory problems including inner ear deficits or cortical dysfunction are rarely reported. A higher prevalence of educational problems has been noted in children with NSCL/P compared to craniofacially normal children. These high level cognitive difficulties cannot be entirely attributed to peripheral hearing loss. Recently it has been suggested that children with NSCLP may be more prone to abnormalities in the auditory cortex. The aim of the present study was to investigate whether school age children with (NSCL/P) have a higher prevalence of indications of (central) auditory processing disorder [(C)APD] compared to normal age matched controls when assessed using auditory event-related potential (ERP) techniques. School children (6 to 15 years) with NSCL/P and normal controls with matched age and gender were recruited. Auditory ERP recordings included auditory brainstem response and late event-related potentials, including the P1-N1-P2 complex and P300 waveforms. Initial findings from the present study are presented and their implications for further research in this area — and clinical intervention — are outlined.
Change deafness with recognizable and unrecognizable sounds
Authors: Irsik Vanessa , Gregg Melissa , Snyder Joel
Published: April 2012

Change Deafness with Recognizable and Unrecognizable Sounds Change deafness is the remarkably frequent inability of listeners to detect changes occurring in their auditory environment. In this study, we used behavioral measures and event-related potentials (ERPs) to determine if change deafness is a fundamental auditory sensory process, rather than simply a reflection of verbal or semantic memory limitations. Change detection performance was examined for scenes composed of four recognizable or unrecognizable sounds. Listeners completed a change detection task by making a same/different judgment for two consecutively presented scenes that were either the same (Same trials) or had one sound replaced by another sound (Change trials). The behavioral data indicated substantial change deafness for both recognizable and unrecognizable sounds, indicating that change deafness is not the result of verbal or semantic memory limitations. In Change trials, N1 ERPs were less smaller in the post-change scene on trials in which the change was not detected, suggesting that change deafness is associated with less robust sensory encoding. P3 ERPs to the post-change scene were also smaller for non-detected changes, which may reflect lack of memory updating, attention, and/or awareness during change deafness. Overall, the results provide novel information regarding the stages of processing involved in change deafness in natural auditory scenes.
What is so hard about selectively attending?
Authors: Maddox Ross K , Cheung Willy , Lee Adrian KC
Published: April 2012

As the number of elements that make up an auditory scene increases, it becomes harder to selectively attend just one of those elements. Previously, the limit of listeners' abilities to attend a target stream of repeating letters in an overcrowded scene was tested. In that experiment, each stream consisted of a repeated monotonized and localized spoken letter (an “item”), with a repetition period of 1 s. Among streams, item onset times were distributed across each repetition. Listeners were asked to detect when the attended target letter changed to an oddball “R” for a single repetition, ignoring such occurrences in the non-target streams. With a constant repetition period, adding streams to the stimulus meant that the number of items per second increased proportionally. The decrease in performance could thus be a result of having more streams in the scene, or because of the increased item rate. Here, a similar experiment was performed, holding the item rate constant, rather than the repetition period. The results allow us to disentangle the effects of the number of distractor streams and the item rate, yielding insight into the specific reasons for the diminished ability to selectively attend. Funded by USA-NIH-T32DC009975 (RKM) and R00DC010196 (AKCL).
Probing the cortical dynamics involved in ignoring a low-salience distracting sound
Authors: Larson Eric , Lee Adrian KC
Published: April 2012

Verbal communication in many everyday settings requires listeners to ignore distracting auditory events. However, how the brain coordinates the suppression of even low-salience auditory distractors remains unclear. In studies of visual attention, it has been observed that the frontal eye fields (FEF) are involved in orienting and maintaining attention to targets of interest. With multiple fMRI studies implicating FEF in orienting auditory attention, we sought to examine the temporal dynamics of auditory attentional control in the presence of a low-salience distractor. We utilized a task that required listeners to attend to and report one of two simultaneous, but spatially-separated, spoken digits. A visual arrow-cue prompted listeners to report the stimulus originated from that hemifield. Shortly following the visual cue, we presented listeners a noise burst that either originated from the same hemifield or the opposite side as the visual cue. We utilized simultaneous magneto- and electro-encephalography to investigate the cortical dynamics involved in suppressing the potentially distracting noise burst. Using source-space analysis, we observed significantly stronger activation in left FEF when the noise burst was presented in the to-be-attended hemifield, providing further support that left FEF is specifically involved in maintaining auditory spatial attention. Funded by USA-NIH T32DC000018(EL) and R00DC010196(AKCL).
Visual deprivation improves auditory scene analysis
Authors: Houde Marie-Soleil , Bélanger Marianne , Shiller Douglas , Champoux François
Published: April 2012

The present study aims to examine the effect of temporary visual deprivation on a process central to auditory segregation, namely harmonicity. A harmonicity discrimination task was administered twice, with an interval of 90 minutes, in two groups of individuals. One group was temporary deprived of visual information during that interval period. Control conditions revealed that auditory capabilities were similar across groups. However, results in the subsequent testing session revealed that temporarily deprived individuals showed a remarkable improvement in the auditory task in comparison with the non-visually-deprived group (i.e. control group). These results suggest that temporary blindness can improve auditory segregative processing.
Acoustical dummy head for Chinese adults
Authors: QI Na , MENG Zihou
Published: April 2012

An acoustical dummy head is designed based on the Chinese national code of adult head geometry. From a survey of more than four hundreds Chinese adult auricle structure, a typical physiological structure of auricle is selected for the acoustic dummy head. Eyes, nose and other head structure are simplified. The HRTF of the acoustical dummy head is measured. The cues relating to sound source localization, including interaural time difference (ITD),interaural level difference (ILD), and spectral features introduced by pinna, nose, hair and other detail structure of head, are analyzed. And then the analytical data is compared with a full-scale dummy head. The result shows that the acoustical dummy head retains the main acoustic characteristics attributed to auditory localization. A listening test is carried out to verify this property.
Estimating listeners' internal noise from intensity and spectral-shape discrimination tasks
Authors: Dai Huanping , Chuang Feng-Yi , Lotto Andrew
Published: April 2012

Within the framework of signal-detection theory, listeners' ability to process stimulus information is partly limited by their internal noise. Knowing the internal noise of listeners will allow the researcher to predict their performance in various detection or discrimination tasks. For the purpose of estimating internal noise, in this study we measure the ability of listeners to discriminate the intensities of pure tones (Exp. 1) and two-tone complexes (Exp. 2), and to discriminate the spectral shapes of two-tone complexes (Exp. 3). The results from five listeners were fitted with an internal-noise model. The analysis showed that a major portion of the internal noise is correlated across frequency channels. This outcome is consistent with the conclusions of previous studies that estimated internal noise using different methods. Under the dominance of channel-correlated internal noise over channel-specific internal noise, listeners' ability to integrate information over frequency should be reduced, and their performance in detection and discrimination should be less affected by uncertainty for the signal parameters.
Behavioral and electrophysiological measures of stimulus envelope and fine structure contributions to the binaural masking level difference
Authors: Eddins Ann Clock , Kline Makenzie , Eddins David A.
Published: April 2012

The goal of this study is to establish electrophysiological methods for estimating the relative contribution of stimulus envelope and fine-structure cues across a range of clinical populations using a binaural masking level difference (BMLD) paradigm. Stimulus envelope cues were manipulated by the using narrowband noise maskers (50 Hz) with the inherent envelope fluctuations of Gaussian noise (GN) or the reduced envelope fluctuations of low-noise noise (LNN). Fine-structure cues were manipulated by choosing signal frequencies and masker center frequencies of 500 and 4000 Hz. The availability of fine structure cues to the auditory system differs markedly between these two frequencies. Electrophysiological measures consisted of far-field evoked potentials targeting the P1-N1-P2 cortical components. Stimulus maskers were presented continuously at a spectrum level of 60 dB SPL while signal level was varied in descending steps. Threshold was estimated as the lowest signal level that generated a reliable N1-P2 response. Validation of cortical indices was achieved via behavioral measures of the BMLD. Signal level was varied using an adaptive three interval, three-alternative forced choice procedure with a three-down, one-up adaptive tracking rule. Raw thresholds and derived BMLD values using both measurement methods will be reported for a baseline population of 10 young, normal-hearing listeners.
Explorations by the visually impaired of real and virtual rooms
Authors: Katz Brian , Picinali Lorenzo
Published: April 2012

Virtual acoustic simulations of two interior environments were presented to visually impaired individuals. Interpretations of the acoustic information, through block map reconstructions, were compared to reconstructions following in-situ exploration as well as playback of binaural and Ambisonic walkthrough recordings. Simulations used off-line HOA RIR synthesis and a hybrid rendering combining pre-convolved signals and real-time convolutions for sounds related to user displacement and self-generated noise. Results showed that listening to passive binaural playback or Ambisonic playback, which also included interactive head-movements, provided less usable information than a virtual simulation with respect to the acquisition of spatial information of an interior architectural environment. The presence of both dynamic cues relative to displacement and controlled events such as finger snaps, as included in the virtual condition, were deemed highly valuable by the participants. Virtual acoustic simulations provided acoustic information that allowed for highly correlated detailed map reconstructions relative to a real exploration condition. Some differences were found between the two experimental corridors, with the more complex environment offering better results than the corridors with more diffuse noise sources. This study was supported in part by a grant from the European Union (STREP Wayfinding, No. 12959).
Adaptive prey tracking by echolocating porpoises studied with acoustic tags
Authors: Wisniewska Danuta Maria , Johnson Mark , Beedholm Kristian , Madsen Peter Teglberg
Published: April 2012

Studying the behavior of aquatic echolocators and their prey has proved to be challenging. However, recent studies using Dtags on several toothed whale species in the wild have identified sequences of echoes interpreted as stemming from ensonified prey, along with accelerometer signatures possibly indicative of feeding events. The present study aimed at verifying those findings in a controlled environment, and elucidating what echograms may tell us about echolocation behavior during prey capture. We applied DTAG-3 tags, sampling sound at 500 kHz, to trained harbor porpoises during captures of dead and live fish of different species and sizes. To look at details of the feeding events, we used tag-synchronized high-speed underwater cameras. The prey targets gave rise to echoes that could be traced back to ranges of up to five meters and often tracked in the high repetition rate buzzes initiated at short ranges. These buzzes were typically closely tied to distinct acceleration signatures of attempted prey captures. Results show that porpoises can carefully track their prey with adjusted click intervals both during approach and buzz phases and can dynamically accommodate prey movements to provide high spatial resolution without range ambiguities.
Three-dimensional quantification of freshly-excised human lymph node properties using high-frequency ultrasound
Authors: Mamou Jonathan , Coron Alain , Saegusa-Beecroft Emi , Hata Masaki , Oelze Michael L. , Yanagihara Eugene , Yamaguchi Tadashi , Laugier Pascal , Machi Junji , Feleppa Ernest J.
Published: April 2012

Human lymph nodes excised from cancer patients during lymphadenectomy can contain small clinically-important metastatic regions that can be missed because conventional histopathology methods do not allow nodes to be examined over their entire volume. In this study, more than 250 lymph nodes were scanned in 3D using a 26-MHz ultrasound transducer before histology processing. Acquired radio-frequency data were processed using 3D regions-of-interest to yield thirteen quantitative ultrasound (QUS) estimates. The QUS estimates are related to tissue microstructure and are hypothesized to be different in normal nodal tissue and metastatic tissue. Four QUS estimates were obtained from backscattered spectra and the remaining nine were derived from envelope statistics. Following ultrasound scanning, serial-section histology was performed at 50-μm intervals to depict cancer foci in 3D. Classification based on QUS estimates was performed using linear-discriminant analyses in a step-wise approach, and areas under ROC curves (AUCs) were computed. The AUC for the linear combination of four QUS estimates was 0.87 for a dataset of 95 breast-cancer nodes. Similarly, using only two QUS estimates, an AUC of 0.95 was obtained for a dataset of 160 gastrointestinal-cancer nodes. These results suggest that QUS may provide an effective tool for detecting metastatic foci in lymph nodes.
Automatic segmentation of ultrasound contrast images of arteries for determining boundaries between arterial inner walls and blood flows: in vivo animal studies
Authors: Qian Ming , Niu Lili , Song Ruibo , Qi Guan , Zheng Hairong
Published: April 2012

Ultrasound contrast images could be used together with ultrasonic particle image velocimetry technology to obtain multi-component field of arterial blood velocity and shear stress, which is helpful to understand atherogenic process and predict plaque rupture. Near-wall flow can hardly be measured accurately due to artery pulsation and tissue movement. Measuring accuracy for PIV analysis can be improved by detecting the boundaries between arteries and blood flow and determining region of interest in arterial ultrasound contrast images. A fully-automatic algorithm is proposed, which is named as time frame difference snake(TFDS). The ultrasound contrast images are subjected to median filter using a window frame difference method to de-speckle the lumen and highlight the arterial wall. The filtered image is subsequently subjected to an automatic initialization procedure to obtain the initial contour for the snake model. The TFDS model takes advantages of the standard deviation matrix of consecutive images, and is applied to obtain the final delineation of the boundary. Ultrasound contrast images of mouse carotid arteries are used for performance evaluation. The computer-generated segmentation is compared with the hand-outlined delineations. Statistical analysis shows that our algorithm's segmentations agree with that of trained operators for both the near-end and far-end carotid artery wall.
A binaural hearing assistance system with front-back discrimination capability
Authors: Usagawa Tsuyoshi , Saho Atsuya , Chisaki Yoshifumi
Published: April 2012

Binaural hearing assistance systems have a well known ambiguity in front-back discrimination which is called as “front-back confusion” or “cone of confusion” in psychoacoustics. It is known that spectral cue of sound provides keys to solve this confusion in binaural listening condition and the peaks and notches of spectral components play main role to estimate the vertical angle in sagittal coordinate. In this paper, a binaural hearing assistance system with new front-back discrimination method is proposed. The discrimination method is implemented on an artificial neural network using interaural level and phase differences as input in selected frequency bins. The performance of the proposed system is examined for simulated conditions as well as experiments.
On direct optimization in mode space for robust supergain beamforming of circular array mounted on a finite cylinder
Authors: Wang Yong , Yang Yixin , Ma Yuanliang
Published: April 2012

A direct optimization method in mode space for robust supergain beamforming of circular array mounted on a finite rigid cylinder is presented. According to the concept of eigen-decomposition, the beam pattern is decomposed into a series of eigen-beams weighted by modal coefficients. The modal cross spectral matrix in isotropic noise field is calculated from sound scattering theory based on boundary element method(BEM). This beamforming method gives the most suitable modal coefficient vector directly under the related constraint conditions via second-order cone programming, so that there is no need to transform indirectly from the weighting vector in sensor space which is essential in the modal robust supergain beamforming method proposed before. The results of simulation show that the direct modal beamforming method in this paper can not only improve robustness using the white noise gain constraint, but also change the mode orders to provide trade-off between array gain and robustness in low frequencies. Beam performance measures such as sidelobe level can be optimized in addition to array gain, and in this way more effective schemes for designing practical robust supergain beamformers can be developed.
Noise control for 24-hour rock drilling in urban area
Authors: HO Wilson , CHU Isaac , Baranger Etienne , Kwan Richard
Published: April 2012

Dill and blast is often utilized for construction of vertical shaft in hard rock geology for various tunneling projects in Hong Kong. Such excavation work is usually restricted during 1900-0700 hours due to noise concern, especially in urban area. For MTR West Island Line Contract No. 703 SHW to SYP tunnels, extensive noise mitigation measures have been employed at the Tunnel Boring Machine (TBM) launching shaft where located less than 10m from the nearest noise sensitive receiver (NSR). A well deigned shaft cover is the most prominent feature of noise mitigation measures and the insertion loss of the shaft cover was found to be minimum 49dB(A) on site. Groundborne noise impact from rock drilling was predicted within the statutory criteria and verified on site. Construction noise permit for 24-hour rock drilling by 2-boom jumbo drill was obtained.
A deterrent to repeated noise offences
Authors: Chan Louis P.L. , Wong C. L. , Cheng K.W. , So T.W.
Published: April 2012

Since the Noise Control Ordinance (NCO) was implemented in 1989, various environmental noise sources and activities have been regulated through different control mechanisms. Nevertheless, the penalty in terms of fines imposed for breaches of the NCO seemed not sufficient to deter the recurrence of offences, in particular during the 90s, when Hong Kong was actively enhancing its infrastructure to accomodate the growth of its thriving economy. Although the maximum fines under the NCO had been doubled in 1994, repeated violations were still serious at that time, with one reason being the continued disregard of those legal requirements by the corporate management. Despite the court had in some offence cases actually imposed the maximum fines, the corporate management simply treated the fines as part of project expenses as they were not held personally liable for the actions of their companies. That malpractice was also disturbing a level playing field in the industry, creating unfairness to other law-abiding persons. A legislative amendment was successfully introduced in 2002 to hold the top management of bodies corporate personally liable for repeated noise offences. This paper will describe the framework of this provision with reference to similar legislation in other countries. The corresponding deterrent effect over the past years would be analysed. Moreover, a code of practice providing practical guidance to prevent violation would also be discussed in the paper.
An active vibration control method based on nonlinear reverse model and Fx-LMS algorithm
Authors: Yan Li , Lin He , Changgeng Shuai
Published: April 2012

The Filtered-X algorithm based on linear adaptive filters had been widely used in the active vibration control, but its effectiveness was limited by the nonlinearity of the active actuators. In this paper, the nonlinear reverse model of actuator was built using polynomial method and neural network algorithm, and an improved Fx-LMS algorithm based on reverse model linearization was put forward to address the nonlinearity of the actuators in active vibration isolation system. Simulation and experiment showed that the improved Fx-LMS algorithm had better effect on periodic vibration control with nonlinearity compared with the traditional Fx-LMS feedforward control method.
Low creep isolator design and research for Ship propulsion engine
Authors: Lihong Shu , Lin He , Xue Yang
Published: April 2012

A mechanical model based on Zener component was presented, which can perfectly describe and predict the creep characteristics of materials as parameters can be extracted with genetic algorithm not only from the step loading process, but also from the no-ideal loading process. This model can be applied to numerical calculation and prediction of vibration isolator's creep characteristics. The creep characteristic of the isolator has relationship with the creep characteristics of materials and the structure of the isolator. We can get the best creep characteristic and appropriate static and dynamic properties of the isolator by right design. A type of low creep vibration isolator made in polyurethane was designed for ship propulsion engine. Experimental results accorded with the numerical calculation result well.
Study on the dynamic model of magnetorheological elastomer vibration isolator
Authors: Xue Yang , Lin He , Changgeng Shuai
Published: April 2012

Magnetorheological elastomers vibration isolator is a new controllable device, which shows a widely application in active or semi-active control. In fact, it is very important to constitute a precise dynamic model of the MR elastomer isolator, which gives help for design the control strategy and control method, and achieve good control effectiveness. At present the models is convenient to analyze and calculate the change of MR elastomer's properties, but it can not put up the saturation of the stiffness and the parameter of model is magnetic field strength which adding the complexity of engineering application. In this paper, a phenomenon model was constituted to describe the dynamic performance of the MR elastomer vibration isolator. Using the test results of the isolator, parameters of the model were achieved. By comparing the simulation results with the test results, we can find that they tally well with each other, which validates the dynamic model.
A study of designing and computational method of single convoluted air spring
Authors: Yinglong Zhao , Zhiqiang Lv , Lin He
Published: April 2012

The method of design and calculation of single convoluted air spring is studied in this paper. And the method is used to design an air spring which is meet the demand. The load, static stiffness, dynamic stiffness, and normal frequency of the air spring are calculated and tested. The aramid cord filament framework layer of the air bag and the air inside are modeled by the Rebar Element and Cavity Element of the MSC.Marc software respectively. And the nonlinear Finite Element Analysis (FEA) model is obtained. The characteristics of the air spring are calculated by FEA. Lastly, the characteristics of the air spring are tested by the MTS test machine. The design and simulation results are accord with the experiment results. The theoretical analysis and experimental results indicate that the design method is simple and exact, the nonlinear FEA model simulate exactly the air spring, and the design and simulation method can be used to design the single convoluted air spring.
The acoustics approach to new towns and buildings planning
Authors: Wong James Wing Ho
Published: April 2012

Sound have been known to affect the physical, emotional, mental and spiritual states. Sound affects pulse rate, skin temperature, blood pressure, muscle tension, and brain wave activity. It helps release biochemicals, such as endorphins. It relaxes, excites, releases emotions, and helps to travel to altered states of consciousness. Sound has been applied in architectural design in ancient times and recent years, it helps in healing all those disease in which stress plays a role. This study develop advanced acoustic design concepts in use of sound healing in new towns and buildings planning. Harmonic building design and town planning is an exciting and emerging field that links the ancient sciences and arts with sound and vibration to heal the spirit, mind and body. The goal is to assist the individual and community at large in establishing healthier patterns for living in wholeness. It draws fundamentally on a unified view of the cosmos in which all things are inextricably bound and in relationship to one another whether it be an organ system, a family or an ecosystem. When our bodies experience an illness or disharmony, this will initially develop within the organizational energy matrices. The energy matrix of the body's cellular makeup is made up of a highly complex multitude of frequency interactions. When the body is subject to sound stimulation, it sets up a series of harmonic oscillations that influence a change in phase and frequency in the energy field or matrix on the cellular level. The result will be to reorganize the energetic matrix back to a more balanced state. This paper investigate how does sound and harmonic healing work. What is a typical resonance based building look like? What is the underlying concept about resonance healthy communities and how can Harmonic Town Planning design techniques be applied to create healthy communities.
A study on acoustical protection effects of plenum windows
Authors: Tong Y.G. , Tang S. K.
Published: April 2012

Urban noise is likely to continue as a major issue in densely populated cities. The use of natural ventilation for energy saving and sustainable reasons become difficult to implement for the buildings in noisy urban environments. A staggered inlet and outlet openings design of plenum window was investigated in the present study. Two-dimensional model simulation was used to examine the effect of acoustic benefits of this window system relative to the different sound incidence of angle by solving numerical Helmholtz equation. Fully opened window is used as reference case. The results show that the insertion loss of plenum window is affecting by its staggered design and orientation of the window. There is peak of insertion loss observed at lower frequency which becomes sharper when the opening size of the window becomes smaller. [Y.G. Tong sponsored by Ministry of Higher Education, Malaysia.]
Comparative study of military impulse noise criteria currently in use and identification of research needs
Authors: Goley Steve , Kim Jay
Published: April 2012

Impulse noise criteria currently being in use, such as MIL-STD 1474D, Pfander, Smoorenburg and LAeq8hr, employ respectively a different noise metric to estimate the exposure risk to military noises. In these criteria, the risk is assessed based on the characteristics of the noise such as the peak level or equivalent energy. Recently a new approach that utilizes a simulation program of the auditory system called AHAAH is advocated as an alternative, which considers characteristics of not only the noise but the auditory system response in assessing the risk. In this work, underlying assumptions and analytical structures of widely used impulse noise criteria and AHAAH are examined to understand their relative strengths and shortcomings. Then, performances of the criteria are compared by utilizing an existing animal data obtained by exposing chinchillas to various impulse noises. Linear correlations of the noise metric with the PTS at 0.5, 1,2,4 K-Hz inflicted in chinchillas are used as the basis of the comparison which indicates that LAeq8hr and AHAAH show better performance. Research needs to enable improvement of existing criteria and development of a new improved criterion are discussed. Acknowledgment: Travel for this invited presentation was supported by the Air Force Research Laboratory
Changes in distortion product oto-acoustic emissions after exposure to continuous and impulsive noise
Authors: Aranda de Toro Miguel Angel , Ordoñez Rodrigo , Hammershøi Dorte
Published: April 2012

Temporary changes in the hearing of human subjects were monitored with distortion product otoacoustic emissions (DPOAEs) after control sound exposures in a laboratory. The objectives of the experiment were to investigate whether the +5~dB penalty for impulsiveness used in international standards and legislation correlates to a higher risk of hearing damage. Subjects were exposed to two types of binaural recordings consisting of a continuous broad-band noise-exposure normalized to LEX,8h = 80~dB and the interaction of the previous stimulus with a noise of impulsive character normalized to LEX,8h = 75 + 5~dB penalty = 80~dB. The results show that the effects on DPOAE levels from the two stimuli could be compared in terms of their total acoustic energy.
Using impulsive peak insertion loss of hearing protectors with impulsive damage risk criteria
Authors: McKinley Richard , Gallagher Hilary , Murphy William
Published: April 2012

Impulsive noise presents special challenges for hearing conservation. The scientific community continues to search for an impulsive noise exposure criterion which accurately assesses the hearing damage risk for both short and long duration impulses. Other factors, such as the use of hearing protectors, earmuffs and earplugs, also affect the hearing damage risk but the current criteria do not address methods for using the attenuation of hearing protectors in impulsive noise. The relatively new ANSIS12.42-2010 “Methods for the Measurement of Insertion Loss of Hearing Protection Devices in Continuous or Impulsive Noise using Microphone-in-Real-Ear or Acoustic Test Fixture Procedures” describes methods for measuring the peak insertion loss of a hearing protector in impulsive noise. This paper will describe a method to apply the peak insertion loss data to impulsive noise damage risk criteria for an estimate of allowable impulsive noise exposure when using hearing protection.
A hybrid model for predicting the sound level of shooting noise from recoilless rifles
Authors: Kong Byunghak , Lee Kyuho , Lee Soogab
Published: April 2012

In the present study, acoustic signals from M40A1 recoilless rifle were measured according to recommendations of International Organization of Standardization (ISO) using B&K 2250 sound analyzers. Contrary to expectations from previous studies about shooting noise, the signal recorded at each point shows different waveform in comparison with the others. This means that an additional acoustic source was present, and there was no doubt that it was located at a tail nozzle of the weapon through temporal and geometric relations between the microphone arrays. Spectral analysis and frequency band filter were used to find out what kind of acoustic source there was, and it was concluded that acoustic properties of the additional source was much close to those of jet noise rather than blast noise. Based on these results, consequently, a hybrid model has been developed to predict the sound pressure level of shooting noise from recoilless rifles using predicting algorithms applicable to acoustic sources, blast noise and jet noise, relatively.
Negative optical torque
Authors: Ng Jack , Chen Jun , Lin Zhifang , Chan C. T.
Published: April 2012

While it is now clear that optical scattering force can be negative (opposite to the propagating direction of the beam), less attention is being paid to the optical torque. Here, we show that the optical torque exerted on a structure by an electromagnetic wave can be in an opposite direction to the angular momentum of the incident beam. This negative torque is closely related to the symmetry of the structure, and by playing around with the rotational symmetry and density of the structure, one can control the magnitude of the negative as well as the positive torque.