bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration analysis of moderately thick rectangular plates with elastically restrained edges
Authors: Du Jingtao , Li Wen L. , Yang Tiejun , Liu Zhigang
Published: April 2012

In this paper, an improved Fourier series method is proposed for the free vibration analysis of moderately thick rectangular plates with uniform elastic restraints along each edge. The effect of shear deformation is considered by using Mindlin plate theory (namely, the first order shear deformation theory). The transverse deflection and rotation displacement functions are invariantly expressed as the superposition of a double Fourier cosine series and four supplementary functions in the form of the product of a polynomial function and a single cosine series expansion introduced to ensure (accelerate) the uniform and absolute convergence (rate) of the series representation on the plate including four edges. The unknown expansion coefficients are determined using the Rayleigh-Ritz procedure in conjunction with the energy formulation of Mindlin plate system. Several numerical examples are presented to demonstrate the effectiveness and reliability of the proposed method for predicting the modal parameters of rectangular Mindlin plates with various thickness-length ratios under different boundary conditions. Although the constraint is considered uniformly distributed over each edge, the current method can be readily extended to the general cases when the spatial variation of the restraining stiffness is of interest.
Prediction of cavity noise with multiple layer composite plate as the back panel induced by the turbulence
Authors: Shijin Lv , Xiaobin Liu , Mengsa Yu
Published: April 2012

Cavity noise in the cube with multiple layer composite plate as the back panel was predicted and analyzed in this paper. The mode solution was used to solve this acoustical problem,the mode strain and stress transmission matrix in the composite plate was built up,this paper chose the Corcos model as the turbulent boundary layer pressures's wavenumber-frequency spectrum.The cavity noise was calculated,the sound pressure level's difference between the theory and experiment was less than 3dB,the method in this paper can be used to predict the cavity noise underwater.
Text-independent pronunciation quality automatic assessment system for English retelling test
Authors: Qi Yaohui , Dong Bin , Ge Fengpei , Yan Yonghong
Published: April 2012

An automatic grading system for spoken English retelling test is presented in this paper. Speech recognition technology is used in the system to evaluate the quality of retelling according to the pre-defined scoring rubric which includes speech fluency, pronunciation accuracy and content integrity. Scoring features for these quality aspects are firstly extracted by applying LVCSR, keyword spotting, forced alignment and confidence measurements. And then, these features are mapped to a score by using SVM model which is pre-trained on human rated test items. According to the experimental results the correlation coefficient between machine scores and expert scores is 0.729, which means that the system can be used in real examination to replace human scores. This work is partially supported by the National Natural Science Foundation of China (No. 10925419, 90920302, 10874203, 60875014, 61072124, 11074275, 11161140319).
A study of feature selection in phonotactic language recognition
Authors: Liang Chunyan , Yang Lin , Wang Junjie , Yan Yonghong
Published: April 2012

This paper is a comparative study of feature selection methods in phonotactic language recognition. The phonotactic feature is presented by n-gram statistics derived from one or more phone recognizers in the form of high dimensional feature vectors. Feature selection is necessary for its ability of reducing the dimension of feature vectors so that the higher order n-gram features can be adopted in language recognition. This paper investigates four feature selection strategies that are introduced from text categorization, including mutual information (MI), Chi-squared test (CHI), information gain (IG) and weighted log likelihood ratio (WLLR). These methods are compared on the NIST 2009 Language Recognition Evaluation (LRE) task. The experimental results show that CHI, IG and WLLR can effectively obtain much lower dimensional features without affecting the language recognition performance. In contrast, MI has relatively poor performance due to its bias towards favoring rare terms. This work is partially supported by the National Natural Science Foundation of China (No. 10925419, 90920302, 10874203, 60875014, 61072124, 11074275, 11161140319).
Non-negative matrix factorization of mixed speech signals based on improved particle swarm optimization
Authors: Li Hua
Published: April 2012

NMF (non-negative matrix factorization) is a recently addressed speech signal processing method, In this paper, we proposed a new NMF algorithm based on improved PSO (particle swarm optimization) techniques at aims to extract non-negative components with low cross-talking error and high SNR. Compared with standard PSO algorithm, the improved PSO can overcome lower velocity of convergence by updating dynamic inertia weight. Our discussion is supported by experimental results for separating speech signals, which show that the proposed approach exhibits good performance than traditional NMF methods.
High payload audio watermarking using multiple marking spaces
Authors: Shahriar Md. Rifat , Chong Uipil
Published: April 2012

Audio watermarking is the process that imperceptibly embeds desired message into an audio file for the purposes like content authentication, content identification, data monitoring and tracking, and copyright protection. High embedding capacity is one of the desired requirements of every watermarking algorithm that always struggles against other important requirements like robustness and imperceptibility. In this paper we propose a time domain audio watermarking scheme that performs embedding of more than one digital message into the same cover work thus ensuring higher data payload as well as higher capacity. In this proposed approach, different watermark messages are inserted into different marking spaces which are obtained through orthogonal decomposition of the original audio signal. The proposed algorithm exploits perception characteristics of Human Auditory System (HAS) while providing robustness and higher embedding capacity. Our proposed scheme appears to be computationally efficient and simulation results confirm its robustness against strong attacks like noise addition, filtering, compression, re-sampling, re-quantizing, geometric distortion.
An overview of acoustic telemetry: 2001 - 2011
Authors: Baggeroer Arthur
Published: April 2012

In 2000 Kilfoyle and Baggeroer authored a review of acoustic telemetry. Since then there has been rapid progress on all aspects of acoustic telemetry. There have been many experimental investigations which have highlighted the doubly spread features of the acomms channel. There have been many advances in single and multichannel equalizers for both channel inversion and channel matched filtering, also known as time reversal, for coherent communications. Nevertheless, the incoherent comms such as MFSK remains a reliable standby by the especially difficult channels. The presentation will highlight the many advances made in acomms of the last decade.
Matched-field processing using time-reversal concept in a range-dependent environment
Authors: Yang Kunde , Zhang Tongwei , Ma Yuanliang
Published: April 2012

Time-reversal processing (TRP) is an implementation of matched-field processing (MFP) where the ocean itself is used to construct the replica field. This paper introduces virtual time-reversal processing (VTRP) that is implemented electronically at a receiver array and simulates the kind of processing that would be done by an actual TRP during the reciprocal propagation stage. MFP is a forward propagation process, while VTRP is a back-propagation process, which exploits the properties of reciprocity and superposition and is realized by weighting the replica surface with the complex conjugate of the data received on the corresponding element, followed by summation of the processed received data. The number of parabolic equation computational grids of VTRP is much smaller than that of MFP in a range-dependent waveguide. As a result, the localization surface of VTRP can be formed faster than its MFP counterpart in a range-dependent waveguide. As the number of parabolic equation computational grids for VTRP is much smaller than that for MFP, VTRP proceeds about 100 times faster than MFP. The performance of VTRP for source localization is validated through numerical simulations and data from the Mediterranean Sea.
Study on single-parameter inversion for shallow oceans
Authors: Qu Ke , Hu Changqing , Zhao Mei
Published: April 2012

A new rapid geoacoustic inversion technique has been developed, by reducing the number of inversion parameters to one instead of multi-parameters inversion. After fitting basic seabed parameters, a new quantity defined as the bottom loss gradient was proposed and single-parameter inversion method was designed accordingly. Seabed properties were inversed directly using single-hydrophone without complex measurement, intensive signal processing and optimization algorithm which once multi-parameters inversion needed. In this study, Experiments at sea proved single-parameter inversion to be effective. Good agreement is also shown between the results of this method and the matched field inversion carried out in the same experiment. The reflective date inverted by the technique also can predict propagation loss accurately. As a convenient way, the single-parameter inversion method proposed a new choice for real-time seafloor properties determination.
Acoustics of vineyard concert hall concerning the audience and the performers
Authors: Chiang Weihwa , Chen Yirun , Yeh Ite , Chen Chiachun , Hsu Yenkun , Lin Wei
Published: April 2012

Designing a vineyard hall is generally considered as more challenging and time consuming than designing a shoebox hall. Acoustics design of a moderately large vineyard hall was investigated by computer simulation regarding both the audience and the performers. Alternative schemes with orthogonal and splayed terraces were developed with design strategies featuring seating arrangement, wall inclining, ceiling pitch, recess of remote side seating, wall splaying, riser slope, and railing arrangement. Low correlations among most acoustical measures indicated the potential for setting diverse design goals. Optimized schemes with a frontal terrace increased high-frequency components of a voice source by nearly 2 dB for the seats surrounding the stage while confined spatial decay of strength and sustained early decay were achieved. Lateral energy fraction was mainly determined by inclination and splaying of the terraces and side walls. Without significantly affecting energy distribution for the audience, layouts of the walls near the stage could cause 4 dB differences in early reflective strength measured between performers.
Coupled volumes and statistical acoustics: preliminary results of an improved analytical model
Authors: Luizard Paul , Xiang Ning , Katz Brian FG
Published: April 2012

Reverberation chambers, coupled to the main audience hall, make it possible to change the acoustics of a hall through the size and location of coupling surfaces. This passive device provides an acoustical variability which exceeds the possibilities offered by heavy curtains and moving reflectors. Since architects and acousticians are interested in predicting models as design tools, several approaches have been developed, using different simulation methods. This study proposes an improvement to analytical models of sound energy decay in coupled rooms, integrating temporal aspects proposed by Cremer and Müller as well as spatial components described by Barron's revised theory. Distances from the primary source located on stage as well as from secondary sources, which are the apertures between reverberation chambers and the main room, to the same receiver are included. Results from this analytical model are compared to those from ray-tracing software and scale model measurements, all based on the same simple shoebox geometry. While single volume rooms generally provide exponential sound energy decays, coupled volumes can present non-exponential decays under specific conditions. Hence adapted quantifiers are used to determine the characteristics of the obtained room impulse responses from the different methods.
Magnetic microbubbles for localised imaging and drug delivery: Development, characterisation and preliminary application in vivo
Authors: Stride Eleanor , Owen Joshua , Mulvana Helen , Pankhurst Quentin , Tang Mengxing , Eckersley Robert
Published: April 2012

The use of coated microbubbles in therapeutic applications, in particular drug delivery and gene therapy, has become a highly active area of research. There remain, however, some significant challenges to be overcome in order to fully realise the potential of microbubbles in these applications. In particular, the difficulty in controlling the concentration of microbubbles at a given site and in ensuring sufficient proximity between bubbles and target cells, has frequently led to disappointing results from in vivo studies. Recent work has indicated that incorporating magnetic nanoparticles into the microbubble coating may provide an effective strategy for overcoming these challenges. Further investigation to fully understand the mechanisms of enhancement and hence optimise the delivery protocols is however required and this is the aim of the present study. Results will be presented from flow phantom studies demonstrating manipulation of bubble suspensions under physiological flow conditions, from high speed imaging used to investigate the dynamic behaviour of single microbubbles and theoretical modelling conducted to support and interpret the experimental findings. Finally results demonstrating in vivo transfection in a mouse model will be presented confirming successful localisation of the transfection site.
Cavitation-enhanced delivery of a self-amplifying oncolytic adenovirus for tumour-selective cancer therapy
Authors: Carlisle Robert C. , Choi James , Seymour Leonard W. , Coussios Constantin-C.
Published: April 2012

Unlike conventional gene therapy, oncolytic adenoviruses selectively infect and replicate within cancer cells, potentially enabling systemically administered yet highly targeted self-amplifying cancer therapy. Until recently, therapeutic efficacy was hindered by limited extravasation of the virus to poorly vascularized tumour regions and by liver toxicity beyond a certain dose. In the present work, co-injection of the virus with contrast agent microbubbles (SonoVue) and exposure of the tumour to ultrasound using a set of optimized parameters (0.5 MHz, peak rarafactional pressure 1.2 MPa, pulse length 50,000 cycles, pulse repletion frequency 0.5 Hz) result in inertial cavitation, which is found to enable increased extravasation and improved distribution of the virus throughout the tumour. Stealthing of the virus using a novel polymer coating results in improved circulation times, yielding a 30-fold increase in tumour viral expression at 3 days relative to delivery without ultrasound. Post-injection survival of mice bearing subcutaneous human breast cancer cell tumours (ZR75.1) of initial volume in excess of 30 mm3 is extended from 22-42 days for the virus alone to 22-80 days in the presence of inertial cavitation (n=7). Ultrasound-enhanced delivery mediated by inertial cavitation is thus expected to play a key role in the clinical application of oncolytic virotherapy.
Characterization of an innovative drug carrying photoacoustic contrast agent: fluorescent polymer microcapsules
Authors: Lajoinie Guillaume , Gelderblom Erik , Chlon Ceciel , Bohmer Marcel , Manohar Srirang , Versluis Michel
Published: April 2012

Local drug delivery is studied to cross biological barriers and reduce the systemic side effects. Multimodal agents are being developed to combine step-response activation with the monitoring of its triggered release. The release can be triggered by acoustical or thermal means, e.g. using thermo-sensitive liposomes. Here we design an optically triggered microcarrier with well-controlled release precision and, in addition, a strong acoustic response in the far field, making the carrier a highly specific photoacoustic agent. The novel biocompatible microcapsules with a shell of fluorinated poly-L-lactic acid mixed with a fluorescent dye were produced with hexadecane oil core as drug-carrier reservoir. Single capsules were excited by a pulsed laser and their responses were monitored through combined ultra-high-speed imaging and sensitive acoustic detection. The experiments support a model where the polymer heats up through dye absorption thereby inducing the shell destruction and the vaporization of the surrounding water, resulting in the core release. Beyond the classical pulsed laser photoacoustics, capsules also respond to CW laser excitation by emitting a continuous signal, which offers promising opportunities for real-time photoacoustics. The subsequent study shows that the prolonged response results from repeated vaporization cycles and a complex interaction of the laser with the dyed polymer.
A downhole forward-looking ultrasonic imaging system
Authors: Lin Weijun , He Hongbin , Liu Lei , Zhang Hailan
Published: April 2012

Inspection and evaluation of casing damages is important in oil fields. Compared to normal casing damage detecting equipments which can only measure the radius of casing around the equipment, the downhole forward-looking ultrasonic imaging system can detect casing damage in front of the equipment. A phased-array transducer was used in this imaging system, the FPGA and DSP were introduced to reduce the size of downhole equipment significantly, and the image of the casing is generated via a series of signal processing, which correctly reflects the real shape of the casing. In addition, we analyzes the factors influencing ultrasonic image quality. It shows that the influences of the three kinds of inconsistency among channels on ultrasonic imaging are trivial. The possible ranges of these inconsistencies are given. Several experiments were completed on damaged casing models by using the downhole forward-looking ultrasonic imaging system. The results show that the methods introduced in this article are valid and this downhole forward-looking ultrasonic imaging system is a complement to existed casing damage detectiong equipments. (This work was supported by the National Natural Science Foundation of China, 10874202, 11134011) Key Words: Casing damage, Phased array, Ultrasonic
Underwater acoustics education in Harbin Engineering University
Authors: Yang Desen , Li Xiukun , Li Yang
Published: April 2012

Underwater acoustic engineering is a discipline for graduate students' study which is currently famous at 6 schools across China, two of which may offer the undergraduate-level program. Underwater acoustic engineering specialty of Harbin Engineering University derives from the first sonar specialty in China built in 1953, which is the earliest institution engaging in underwater acoustics education in Chinese universities. There are three education program levels in this specialty (undergraduate-level, graduate-level and PhD-level), and students may study underwater acoustics within any of our three programs. In this presentation, descriptions of underwater acoustics education programs, curriculum systems, and teaching contents of acoustics courses will be introduced.
Teaching acoustics in Communication University of China
Authors: Xie Lingyun , Meng Zihou
Published: April 2012

There are three specialties with relation to acoustics in Communication University of China. Each specialty has different main courses. The key is how to make good interdisciplinary education between these specialties, so that the students can share different experience and knowledge from both Arts and Science. Practicing is also an important element for acoustics education. The university has good relationship with the industry. The students often have their practical courses and experiments in the corporations and factories. It is a good chance for them to turn their knowledge from books into actual products and experience. In the recent years, more and more students enjoy the benefit from this education strategy in the Communication University of China.
Basic acoustics for graduates: an experience in Uruguay
Authors: González Fernandez Alice Elizabeth
Published: April 2012

The Acoustics area has a very secondary place in the degree studies of Engineering and Architecture in Uruguay. Just a quick overview on environmental and room acoustics is provided for taking in account this issue in the Degree Project. As noise issues are becoming increasingly important in the working market, many professionals are interested on a specific training in this area. Teaching basic concepts for graduates is sometimes not an easy challenge: no one wants to ask questions that would bring out any technical weakness. Some young professionals are invited each year to attend the course to enhance the profiting of the course of basic acoustics for graduates. As they have been working on environmental acoustics during their undergraduate studies, they have no difficulty to manage with room acoustics. When they are invited to join the course, they are asked to have an active participation in classes and to cooperate with their peers, especially in applied issues.
Acoustic education and its exploration at NPU
Authors: Chen Kean , Yang Yonghu , Liang Yong , Zeng Xiang , Yang Kunde
Published: April 2012

School of Marine Engineering (SME), Northwestern Polytechnical University (NPU) offers two undergraduate degree programs bearing on the field of acoustics, including information countermeasure and environmental engineering, of which the former is focused on underwater acoustic signal and information processing and the latter on environmental acoustics and noise control. The SME also provides graduate degree programs involving Acoustics, Underwater Acoustic Engineering, Environmental Engineering and Environmental Science leading to a master's degree, among which the former two also possess competency of doctoral education. As a key subject, the education respect to acoustics has developed its own characteristics of teaching reform. The SME is actively involved in fostering the talent of engineering and internationalization among the students. On the one hand, the school is devoted to improve practical and experimental skills of the students. On the other hand, recent years, Acoustics program at the school is gradually promoting its international teaching program.
Acoustic design education for general liberal arts students
Authors: Nishimura Akira
Published: April 2012

Products and services concerning acoustic design are widely available, and the designers who create and maintain them are generally specialists in acoustic design. Therefore, acoustic design education is important, and much effort has been made by many colleges and schools. However, education for not only designers, but also users of acoustically designed environments is important. For example, knowledge of time alignment of loudspeakers for 5.1 channel surround sound is important for producing a better sound field. Scientific and acoustic knowledge can enrich and improve quality of life by utilizing acoustical technologies, products, services, and environments. An acoustic design class for general students enrolled in liberal arts education has been introduced at the Tokyo University of Information Sciences. The main topics of the class are physical and psychological aspects of sound, noise and noise control, introduction to building acoustics, hearing impairment and hearing aids, soundscapes, music therapy, how to use audio products, sound pictograms, and sound design for video. A questionnaire survey administered to students showed that the class was useful for learning new schemes, technologies, and products concerning acoustic design in their daily life.
Realization of sound space information acquisition system using a 252ch spherical microphone array
Authors: Sakamoto Shuichi , Matsunaga Jumpei , Hongo Satoshi , Okamoto Takuma , Iwaya Yukio , Suzuki Yôiti
Published: April 2012

Sensing of high-definition 3D sound-space information is important to realize total 3D spatial sound technology. Nevertheless, conventional methods cannot sense comprehensive 3D sound-space information at a listening point properly and precisely so that the information can be reproduced simultaneously for many individual remote listeners facing in different directions. To cope with this problem, we proposed a sensing method of 3D sound-space information based on symmetrically and densely arranged microphones called SENZI (Symmetrical object with ENchased Zillion microphones) (Sakamoto et al., 2008). In the system using SENZI, sensed signals from the respective microphones are simply weighted and summed to synthesize a listener's HRTF, reflecting the listener's facing direction. This method is expected to sense 3D sound-space information comprehensively in accordance with the head motion of listeners who are listening in remote places. Dynamic cues provided by the listener's motion are important to render sound localization correctly and stably (e.g., Kawaura et al., 1991; Iwaya et al., 2003). We developed a system using a 252-ch spherical microphone array and FPGAs. This presentation introduces a method of realizing this system as a real-time system using results of analysis related to the accuracy of the synthesized sound-space information of the system.
Ray based virtual time reversal method for the localization of sound sources in reverberant fields
Authors: Xiangyang Zeng , Qianqian Song
Published: April 2012

Localization of sound sources in reverberant fields is significant for the research areas such as noise sources recognition, meeting speaker tracking system, intelligent robot design. Microphone arrays are usually used, however, in most applications in rooms it is practical and economical to decrease the microphones. In this paper, using only one microphone a virtual time reversal algorithm based on the ray-tracing method has been developed according to the reciprocity theorem and the time reversal invariance of linear wave equation. The algorithm has been validated by the localization experiments in a real room and a virtual room. Then the performance of the algorithm under the conditions of various reverberation time, source-receiver distance and sound reflection times has been investigated according to a specified ratio.
Diagnosis and characterization of low frequency noise source for a cable car system
Authors: Wang Wei-Hui , Cheng Chieh-Yuan
Published: April 2012

Noise emission generated by a cable car system in operation condition normally becomes a problem widely disturbing the residents living in extremely quiet environment. The noise source identification and the sound field simulation are discussed and addressed in this article. To identify the noise sources from the tower post of a cable car system, the spectral level of the structure-borne vibration, the near-field sound and the far-field sound are measured and analysed. Unexpectedly, it is found that there exists some special narrow band peak frequencies in the range 50~80 Hz and its multiples of all the measured vibration and sound level spectra. The fundamental peak frequency is identified as the frequency of the periodic regular uneven wire rope surface passing through the sheaves of cable wheels. Which depends on the running speed of the cable, the number of cable strands, the pitch of strands. Besides, the fundamental peak frequency appearing in the sound level spectra away from the surface of the tower post also depends on the vibraitonal mode of the post whether pertaining to radiation mode or not near the fundamental exciting frequency band. This can be clarified and illustrated by the sound field simulation analysis. Keywords: low frequency noise, cable car, structure-borne sound radiation
Surveying the infrasonic noise on a basaltic volcano to understand the eruptive dynamics
Authors: Dupont Aurélien
Published: April 2012

The frequent eruptions of Piton de la Fournaise volcano (Reunion island) release an important quantity of magmatic gas into the atmosphere and generates infrasonic airwaves. The series of volcanic noise recorded, in the near field, on a microbarometer between 1992 and 2008 bring new constraints on the functioning of the eruptions. The detection and the modelling of the waveforms associated to the overpressurized explosions of gas bubbles leads to conceive the volcanic eruption as a puzzle game. The elementary pieces, the eruptive regimes, are characterized and interpreted in the framework of a two-phase flow. The eruptive gas flow is also quantified. The main flow regime is the Strombolian activity where the infrasound signature come from the slug flow bursting. The tracking of the main source of noise, during the eruptions, shows that the size of the gas pockets which are maximum in the starting stage of the eruption, what corresponds to the Lava Fountain regime, constantly decrease until to disappear with the eruption end: the gas volume fraction constantly decrease in the volcanic conduit during an basaltic eruption. The quantitative analysis of the noise produced by the gas flow allows not only to understand a natural system as complex as a volcano but allows also to better monitor it.
Examining a-weighted and c-weighted sound levels and noise code limits in respect to annoyance due to music sources
Authors: Woolworth David
Published: April 2012

C-weighting has recently been incorporated into noise ordinances to address music sources that incorporate high levels of low frequency pulsing; previously C-weighting was reserved for industrial and transportation noise. It is common for complaintants to have valid concerns in regard to audible low frequency noise that does not qualify as a violation based on A-weighted measures and codes. This paper will survey a number of existing ordinances that utilize C-weighting and sampling speed to address these music sources and produce examples of urban propagation and transmission.
Evaluation of annoyance of vibration induced low-frequency noise from rail transit system
Authors: Mao Dongxing , Yang Bijun
Published: April 2012

Vibration from urban rail transit system may cause vibration of buildings in subway system or vibration of bridges in elevated rail system, this vibration from building or bridges will generate so called vibration induced secondary noise with a strong low frequency character. Although the A-weighted level is below the limit of local regulations, frequent complains showed A-weighted level not a proper criteria for annoyance. Many research work have been done on low frequency noise, but diversify results were shown in the literature. In this paper, frequency and level depending property of annoyance from rail transit vibration induced low frequency noise was studied through subjective evaluation, and a LF-weighting curve was proposed on the basis of A-weighting curve with the correction below 500Hz, with mathematical description formulated and correction value tabled. Calculated levels according to the proposed LF-weighting curve showed high correlation with subjective annoyance. Results of subjective annoyance on sound level showed that annoyance growing exponentially with the increase of linear SPL. Thereafter, a comprehensive mathematical relation between annoyance and frequency and strength of noise was built, and proved to be effective in evaluating the annoyance caused by low frequency noise from rail transits.
A two domain method for design and evaluation of floor-ceiling assemblies using tapping machine impact sound pressure levels
Authors: LoVerde John , Dong Wayland
Published: April 2012

Structure-borne impact noise from footfalls is a common noise complaint in multi-family residential buildings, and is currently described by a single-number metric such as IIC (using a tapping machine) or LA max (using an impact ball). However, research indicates that impact noise is characterized by two independent frequency domains: low frequency thudding and mid- to high-frequency noise from heel clicks, etc. The levels in these two domains vary independently with assembly design, so that two parameters are required to adequately characterize the impact insulation of an arbitrary assembly. The authors have developed a two-parameter system for evaluating impact noise [LoVerde and Dong, J. Acoust. Soc. Am. 122, 2954 (2007), J. Acoust. Soc. Am. 125, 2708 (2009)] intended to improve the design and evaluation of floor ceiling assemblies. Over the past 7 years, this system has been applied to design, evaluation, and testing of many projects. Criteria have been developed, and the real-world use of the proposed system is described, evaluated, and compared with the existing metrics.
Elevator equipment noise mitigation for high-rise residential condominium
Authors: Evans Jack B
Published: April 2012

A new high-rise hotel and residential condominium building had elevator equipment rooms between residential spaces. During construction, elevator equipment noise was audible in adjacent unfinished residential spaces. The developer and architect requested evaluation by an acoustical engineer. Investigatory observations with acoustical and vibration measurements were conducted to determine sources and paths of vibration and noise transmission. Construction noise and the unfinished condition prevented measurements reflective of actual future conditions in occupied spaces, but 1/3 octave vibration measurements in the elevator equipment rooms and on wall surfaces of residential space indicated structure borne vibration transmission that could result in re-radiated audible sound. Sound spectrum measurements in the elevator equipment rooms compared with anticipated airborne noise transmission loss through the demising partition indicated potential levels of residual elevator equipment noise in residential spaces. Primary acoustic sources were determined by observations and validated by vibration and measurements in the equipment room. Anticipated noise levels due to airborne sound and structure borne vibration were compared to full-octave background noise Room Criteria (RC) to determine attenuation requirements. Recommendations for noise and vibration mitigation were developed. Mitigation measures implemented by the construction contractor will be enumerated with subjectively determine results.
Development of cleaning machine for drainage asphalt pavement in Japan
Authors: Kubo Kazuyuki
Published: April 2012

Drainage asphalt pavement has become popular since 1990s in Japan, especially in expressways in order to improve traffic safety in rainy days and national highways in order to reduce traffic noise. It had regarded to be problem that these effects of drainage asphalt pavement could not last longer. For example, it could reduce traffic noise in 3 dB as its initial performance, while this effect would be lost in three years by clogging. To solve this problem, cleaning machines have been developed in Japan, which uses high pressure water and vacuum system to remove dust in drainage asphalt pavement. As a result, these machines are proved to be able to remove dust from drainage asphalt pavement, however, they can't recover its noise reduction performance to the initial level. Adding to say, the speed of these machines were around 5km/h and were regarded not to be appropriate for on-site maintenancework. Therefore, further development has been conducted to improve its workablility. Finally, new cleanign machine using only high pressure air was developed. In this paper, short histry of this development and their actual use are reported.
A prediction method for tire tread pattern noise based on characteristics of single tire tread block noise
Authors: Lu Yinxiao , Chen Zhenyi , Ge Jianmin
Published: April 2012

Tire tread pattern noise is the main source of tire noise. It contains several noise generation mechanisms such as `air pumping' mechanism, `air resonant radiation' and `pipe resonances'. In the past 40 decades, a lot of researches have being made and many achievements have being won. But there is still no good prediction model or method for tire tread pattern noise. The paper provides a new method for tire tread pattern noise prediction. Make a superposition of noise signal of single tire tread block acquired in drum laboratory in time-domain and space. And give a noise prediction of tire which is full of tread block. The result of prediction and measurement will be compared to validate the effectiveness of the method.
A review of the interior noise and vibration characteristics of modern Chinese high speed train
Authors: Sui Fusheng , Shen Anne , Cheng Jiumei , Yuan Minmin
Published: April 2012

In the past few years, extensive experiments have been carried out to investigate the interior noise and vibration characteristics of modern Chinese high speed trains. The relationships between the vehicle noise and vibration sources and their contributions to the interior environment are discussed. Possible airborne and structural borne sound transmission paths are identified. The vibration responses of, and sound radiation from, the roof, the floor and the sidewalls of a typical power car are presented. The noise contribution from each of these components to the overall interior sound pressure levels is examined and results are discussed.
Noise and vibration induced by a pantograph of high-speed trains
Authors: Chen Zongguang , Ge Jianmin , Lin Junshan , Sun Zhaojin , Guo Jianqiang
Published: April 2012

Pantographs mounted on the roof of the train body are high projections when they work. Along with the raising of the train speed, noise and vibration generated by pantographs are significant. This paper is aimed at evaluating the contribution of pantograph noise to overall noise of high-speed trains. A number of experiments consisting of noise and vibration measurements near and far from pantographs were performed to investigate aerodynamic noise radiated from pantograph and train roof vibration propagated from pantograph. Test data analysis consisted mostly of comparison of noise/vibration in different regions. The results of the experiment indicate that pantographs are main aeroacoustic sources and the train roof vibration which radiating noise into interior is extraordinary when the train speed is 300Km/h.
Acoustical insertion losses of coupled round edge barrier
Authors: Ng Ho Ting
Published: April 2012

In this research project, Finite Element Numerical Modeling Method is used to compute the low frequency acoustical insertion losses of barriers with different edge shapes. Rectangular, Round Edge and Couple Round Edge barriers are included. The coupled round edge barrier is a hollowed round edge barrier with a slit on the round edge and a tube with a slit placed at the center of the hollow space of the round edge. The result shows that the coupled round edge barrier can produce a higher insertion loss on a specific range of low frequency noise in shadow zone. The shadow zone is also enlarged at the same time. The performance of the barrier is improved by the slit on the coupled round edge barrier under the dual resonator effect.
Acoustic field measurements in a standing wave thermoacoustic refrigerator using time-resolved particle image velocimetry
Authors: Blanc-Benon Philippe , Jondeau Emmanuel
Published: April 2012

A standing-wave thermoacoustic refrigerator consists of a stack of plates placed in an acoustic resonator. Two heat exchangers are located at each stack extremity. The thermoacoustic effect takes place in the thermal and viscous boundary layers along each plate of the stack. It results in a heat transport along the plates and in a temperature difference between the two stack ends. In such devices, the full understanding of the heat transfer between the stack and the heat exchangers is a key issue to improve the global efficiency of these devices. The aim of this work is to investigate the vortex structures, which appear at the ends of the stack and modify the heat transfer. Here, the aerodynamic in the gap stack-exchanger is characterized using a time-resolved particle image velocimetry technique. Measurements are performed in a device operating at a frequency of 200 Hz. Instantaneous velocity fields are recorded at a frequency of 3125 Hz (ie 15 maps per acoustic period). Measurements show that vortex shedding occur at high pressure levels, when a nonlinear acoustic regime prevails, leading to an additional heating generated by viscous dissipation in the gap and a loss of efficiency.
Particle Swarm Optimization method in thermoacoustic problems
Authors: Chaitou Hussein , Nika Philippe , Layes Guillaume
Published: April 2012

Thermoacoustic engine systems convert heat power into acoustic power which is useful to pump heat or to generate electricity. To construct a robust and useful thermoacoustic device, both the acoustic power produced and the exergetic efficiency of this device should have acceptable and meaningful values. In order to attain this objective, an optimization study is strongly recommended and required. In the literature of thermoacoustic research, we found only some limited synthetic optimization methods. This paper presents a new study that incorporates the Particle Swarm Optimization (PSO) method for the first time in the thermoacoustic research in order to optimize the two objective functions, i.e. the acoustic power and the exergetic efficiency. The importance of using the PSO method in thermoacoustic research is highlighted and extensively investigated. In addition, significant conclusions, which are useful for the design of new thermoacoustic engines, are discussed.
Factors influencing on matrix H of acoustic field modulation in the thermoacoustic system
Authors: Zhou Lihua , Xie Xiujuan , Li Qing
Published: April 2012

In the system of acoustic field modulation in the regenerator by double loudspeakers (J. Acoust. Soc. Am. 130(5), 2709-2720 (2011)), the relationship among the pressure, velocity and driving voltages is described by a matrix H. H is a function of configuration and location of regenerator, operating frequency and temperature gradient between heat exchangers. The modulation range of acoustic field will vary with the variation of H. In this paper, the influences of factors (y0/l0, L, f, dTm/dx) on the matrix H are researched. The order of these factors effecting on matrix H is given and discussed. The results show that location L and frequency f have important influence on matrix H than y0/l0 and dTm/dx, which are applicable in acoustic field modulation.
The influence of thermoacoustic regenerator on a traveling-wave acoustic field
Authors: Zhou Gang , Huang Xin , Li Qing
Published: April 2012

Thermoacoustic device can realize conversion between the heat energy and acoustic energy. Regenerator is the core of a thermoacoustic engine or refrigerator, which consists of smooth or tortuous porous media, such as parallel plates or stainless stacked-screen. Due to regenerators, the practical acoustic field is neither a pure standing wave nor a pure travelling wave. In fact, the position, structural parameters of the regenerator and temperature gradient between heat exchangers will strongly influence the oscillating pressure and velocity distribution in the acoustic field, which will bring about different performance for a practical thermoacoustic engine or refrigerator. In this paper, based on linear thermoacoustic theory, a mathematical model of a 1/2 wave-length duct with a regenerator driven by speakers will be built and the influence of the regenerator on the acoustic field distribution will be simulated and analyzed. This research is helpful for comprehensively understanding coupling mechanism between the acoustic field and the regenerator. The work was supported by the National natural science foundation of China (Grant no. 10904154).
Modulating of traveling-standing wave acoustic field in the thermoacoustic resonator
Authors: Huang Xin , Zhou Gang , Li Qing
Published: April 2012

In this paper, a double-loudspeakers model to modulate the acoustic field in the resonator is presented. The acoustic field is modulated by changing the driving conditions, including the amplitude and the phase difference of the driving voltages. A numerical simulation for the acoustic field in the resonator without regenerator is carried out. The calculation results indicate that any traveling-standing wave acoustic field can be obtained by changing the driving conditions. The acoustic field in the resonator with regenerator is also simulated. It is found that the acoustic field in the regenerator can be modulated in a wide range and several targeted acoustic field conditions can be obtained feasibly, which are useful for achieving the optimal thermoacoustic conversion. An experimental device has been constructed and tested. The acoustic field are measured and reconstructed under different driving conditions. The experiment results are in good agreement with the simulations. The device provides a platform for our further study on the thermoacoustic characteristic of regenerator in different acoustic field. This work was supported by the National Natural Science Foundation of China (Grant No. 10904154).
Tuning the Hopf cochlea towards listening
Authors: Gomez Florian , Saase Victor , Buchheim Nikolaus , Bumann Richard , Yan Liang , Stoop Ruedi
Published: April 2012

In a Hopf cochlea, coupled Hopf oscillators of individual frequency each, account for the active amplification of the auditory input. All salient nonlinear aspects of hearing can be traced back to the physical properties of the Hopf oscillators. At each location along the cochlea, the amplification strength is effectively governed by a single real parameter characterizing the distance of the Hopf oscillator from the Hopf-bifurcation point. Using these parameters, given a mixture of input signals (e.g., a set of musical instruments) it should be possible to tune the cochlea towards a single sound component. Introducing an autocorrelation-based tuning measure, we demonstrate the tunability of the Hopf Cochlea on recorded real-life instruments of different timbres and pitches. Despite the strongly nonlinear and therefore interaction-prone nature of the device, strong and simple tuning patterns permit an easy tuning to sounds of varying pitch. Our insights may prove essential for gaining further understanding in the problem of selective auditory attention in a multi-source environment, commonly known as the “cocktail party environment”.
Analyzing objects through time
Authors: Shinn-Cunningham Barbara
Published: April 2012

Most researchers accept that the act of preparing to listen for a source with a particular attribute (e.g., from a particular location or a particular speaker) causes preparatory changes in how subsequent sound inputs are processed, and thus how an auditory scene is analyzed. However, the dynamics of how humans parse an auditory scene are complex and depend upon not only this kind of volitional attentional modulation but also automatic processes. Moreover, perceptual automatic processes depend both on the recent statistical properties of input sound (e.g., regularities that determine whether an input is unexpected / novel versus predictable) and, as at least based on results from our own lab, on what perceptual object was the focus of attention in the preceding moments. For instance, we find that once a given stream of sound is the focus of attention, subsequent sound elements that are perceptually similar are perceptually enhanced in an obligatory process, even in the absence of volitional attentional focus. Similarly, changes in sound attributes that cause perceptual discontinuities disrupt processing of auditory inputs. These factors, which strongly impact human processing of auditory scenes, will be discussed and contrasted with the processing governing many machine algorithms for auditory scene analysis.