bluuebunny/crossref_metadata_2025 huggingface dataset:
Combing spatial impulse response with angular spectrum to simulate pulse ultrasound field and the analysis of simulation errors
Authors: Wu Wentao , Lv Yi , Wang Dong
Published: April 2012

In ultrasound imaging field, the simulation of ultrasound imaging is very important. The calculation of ultrasound field is supporting for the theory of ultrasound imaging and improving quality of ultrasound imaging. Recently, the simulation method of ultrasound imaging is mainly based on spatial impulse response. It is researched how to calculate the ultrasound imaging by combing pulse angular spectrum with spatial impulse response to simulate ultrasound field quickly, And the relationship of pulse angular spectrum and spatial impulse response is researched theoretically. The numerical error of simulation ultrasound field in this method is given. It is proved that the method combing spatial impulse response with angular spectrum is correct and effective. This method provides the base for designing ultrasound imaging system exactly and doing some research in nonlinear ultrasound imaging simulation.
Optimization design of the send-receive combined compound bar piezoelectric transducer
Authors: Meng Xiaohui , Wang Junlin , Xiao Ling
Published: April 2012

Send-receive combined compound bar piezoelectric transducer has been widely used in underwater acoustics and ultrasonic fields. The optimization of the send-receive combined compound bar piezoelectric transducer is studied. The effect of the position and the dimensions of the piezoelectric ceramic elements on the resonance frequency, the anti-resonance frequency and transmitting and receiving response are analyzed. The conclusions are beneficial to the optimization of send-receive combined compound bar piezoelectric transducer.
The accomplishment of the field of the phased array high intensity focused ultrasound using pseudo-inverse method
Authors: Yu Zhongde
Published: April 2012

In this paper, the two-focused field of phased array intensity focused ultrasound have been accomplished using the pseudo-inverse method. To reducing grating-labs, the elements in array are randomly placed. The forward propagation operator from the surface of the array to the set of control points should be known when we use the pseudo-inverse method to get the excitation vector. Because of the element placing with high-frequency and large-size, the relative positions of element need to be estimated accurately. A method to get the high precision three-dimensional coordinates of the element are proposed and so the excitation vector have been get to accomplish the field of two-focus.
University of Hartford undergraduate acoustical engineering programs and teaching philosophy
Authors: Vigeant Michelle C. , Celmer Robert D.
Published: April 2012

The University of Hartford is a small private institution that consists of seven schools and colleges, and is located in West Hartford, Connecticut, USA. A more detailed overview of the acoustical engineering curriculum and laboratory facilities will be discussed. Graduating high school seniors who wish to pursue the study of acoustical engineering at the University of Hartford have two ABET-accredited program options: (1) the Bachelor of Science in Mechanical Engineering (BSME) with Acoustics Concentration and (2) the interdisciplinary Bachelor of Science in Engineering (BSE), Acoustical Engineering & Music, which requires acceptance into the University's music conservatory, The Hartt School. These acoustical engineering programs are within the Mechanical Engineering Department, which is part of the College of Engineering, Technology and Architecture. Both programs require a number of theoretical courses in acoustics and vibrations. These theoretical courses are balanced with hands-on real-world design projects and a number of these projects are done for non-profit organizations to expose our students to service learning. Students participate in these industry-sponsored full-semester design projects at both the sophomore (2nd year) and senior (4th year) levels. As a result, students leave the program with a solid foundation of both the theory and real-world applications of acoustical engineering.
Development of education for acoustics in Hong Kong
Authors: Ng C.F. , Wong C.L. , Huang LiXi , Au Yeung Y.N.
Published: April 2012

Acoustical issues have been important subjects in Hong Kong since its progressive development into a cosmopolitan city. Its densely populated characteristics and vibrant nature are challenges often encountered by professionals of various fields involved in the design and operation of a variety of infrastructures and facilities, from the early stage of landuse planning to daily maintenance of plants and equipment. Acoustical issues have also become livelihood issues as people are demanding better quality of living in terms of their acoustical environment. Hong Kong has been putting efforts to cope with the need to address acoustical issues by the most fundamental means, i.e. education for almost all walks of life, aiming to promote knowledge as well as good practices so as to build a “sound” environment. This paper will describe the development of education for acoustics to meet the challenges in an extremely active city like Hong Kong. The partnering efforts among professional associations, academic institutions, and the industries in fostering professional knowledge and enhancing continual training will also be covered.
Evaluation of dynamic binaural reproduction system for live transmitted xylophone recording
Authors: Madsen Esben , Marković Miloš , Krarup Olesen Søren , Hoffmann Pablo , Hammershøi Dorte
Published: April 2012

For a special teaching application of the telepresence research project BEAMING, a scenario of a remote teacher (the Visitor) teaching a local student to play a xylophone through an embodiment is defined. In order to achieve this, a system is required to record, transmit and render the sound of the xylophone to the teacher in a dynamic scene. In an implementation of such a system, the xylophone is recorded using a mono recording technique. The signal is then processed to spread out the sound of the distributed sound source as multiple point sources in the virtual scene experienced by the Visitor. Finally head tracking allows for a dynamic binaural rendering of the xylophone sound. The goal of this paper is to evaluate the realism of this virtual (auditory) representation of a real xylophone. A listening test is designed to compare characteristics of a real physical xylophone in front of the listener with a rendering using the described system. The evaluation is done with a basis in methods previously used for evaluating the subjective sensation of presence in virtual reality systems, mainly based on questionnaires.
Listening test for three-dimensional audio system based on multiple vertical panning
Authors: Kimura Toshiyuki , Ando Hiroshi
Published: April 2012

In this paper, the novel three-dimensional (3D) audio system is proposed. The proposed system is based on Multiple Vertical Panning (MVP) method and matches to the glasses-free 3D display system in which the size of screen is very large. The vertical position of sound images is synthesized by the panning between two loudspeakers placed at the top and bottom of screen. The horizontal position of sound images is controlled by the position of two loudspeakers. By the proposed system, multiple listeners can simultaneously feel the sound images at the position of objects depicted by the 3D display system. In order to evaluate the auditory performance of the proposed system, the listening test was designed by using the loudspeaker array in which twenty-seven loudspeakers were aligned on the vertical line. Sound images were synthesized by the panning between two loudspeakers placed at the top and bottom of the loudspeaker array. Twelve subjects listened to a sound and reported the position of synthesized sound images. As a result, it was indicated that subjects could feel the synthesized sound images at the position between two loudspeakers placed at the top and bottom of the loudspeaker array.
Acoustic sources joint localization and characterization using compressed sensing
Authors: Ollivier Francois , Peillot Antoine , Chardon Gilles , Daudet Laurent
Published: April 2012

In this work, a Compressed Sensing (CS) strategy is developed in order to jointly achieve two complementary tasks regarding sound sources: localization and identification. Here, the sources are assumed sparse in the spatial domain, and greedy techniques are used for their localization. The case of coherent sources located in a plane is studied both numerically and experimentally at different frequencies. Results show that, in this framework, CS source localization is reliable using a significantly smaller number of microphones than classical techniques (standard or high resolution beamforming techniques), while overcoming some of their pitfalls. We then use a similar technique for the identification of the source nature, i.e. its radiation pattern, and here the sparsity domain is extended to a basis of elementary radiating functions. We present simulation and experimental results using calibrated sources and measurements performed with a 3D array of 80 randomly distributed microphones. This study investigates the limitations of Compressed Sensing in terms of resolution and reliability of the identification, with respect to the number of sensors, the signal to noise ratio and the density of the reconstruction region.
Bi-objective optimization for the vibro-acoustic performance of a double-wall panel
Authors: Zhou Jie , Bhaskar Atul , Zhang Xin
Published: April 2012

This paper presents simultaneous optimization of double-walled panels for minimum weight and maximum acoustic transmission loss. A sandwich construction having poroelastic lining in the core is considered. A general formulation — to calculate transmission loss as a function of frequency of the incident wave in the presence of mean external flow on one side of the double-wall panel — is presented. Biot's theory is used to simulate the poroelastic material. Three types of sandwich configurations are considered and the transmission behavior is studied for a range of Mach numbers and over a frequency band. The objective is to simultaneously minimize the sound transmission and the structural weight. Pareto fronts are obtained. The trade-off between weight and acoustic performance is systematically studied.
Estimation of shear-velocity profiles using shear source data in marine environment
Authors: Dong Hefeng , Nguyen Thanh-Duong , Duffaut Kenneth
Published: April 2012

This paper estimates seabed shear-velocity profiles and their uncertainties using interface-wave dispersion curves extracted from data generated by a shear source. The data were collected by 4C ocean bottom cable in a testing experiment of a shear source in the North Sea. The shear source generated a seismic signature over a frequency range between 2 and 60 Hz and was polarized in both in-line and cross-line orientation. Low-frequency Scholte- and Love-wave were recorded. Dispersion curves of the Scholte- and Love-wave for the fundamental mode and higher-order modes are extracted by different time-frequency analysis method. Both vertical (SV) and horizontal (SH) polarized shear-velocity profiles are estimated by Scholte- and Love-wave dispersion curves, respectively. Bayesian approach is used for the inversion. Differential evolution (DE) global search algorithm is applied to estimate the most-probable shear-velocity models. Marginal posterior probability profiles are computed by Metropolis-Hastings sampling. The estimated SV- and SH-velocity profiles are compared and the results provide possibility of studying seabed anisotropy. We thank Statoil ASA for permission to publish the data. The work is partly supported by NFR under Grant No. 186923/I30.
Inversion of elastic bottom parameters from reflection data
Authors: Zhu Han-hao , Zhang Hai-gang , Piao Sheng-chun , Liu Wei
Published: April 2012

In this paper, the wave reflection at the interface between sea water and the half-space elastic bottom is considered and the sensitivity of reflection coefficient to the geoacoustic parameters, such as bottom density, P-wave velocity and its attenuation, S-wave velocity and its attenuation, has also been analyzed. In order to establish a geoacoustic inversion method with the ocean bottom reflection coefficient, a simulated experiment is carried out in the laboratory tank, where a PVC plate is used as the elastic bottom. In the experiment, a high-frequency underwater sound wave is transmitted by a source at fixed position and received using a hydrophone at different position with equal interval. By processing the measurement reflected signals at different receiving positions, the reflection coefficient for different incident angles can be obtained, with which the simulated bottom parameters have been inversed. An inversion method based on the sound transmission loss in water is also accomplished. These two inversion results are compared with the measurement result obtained according to the time delay for received multipath signals which reflect/refract at the liquid/elastic or solid/liquid interface of the PVC plate and the feasibility and reliability of the inversion from reflection data are discussed at last.
Binaural room impulse response database acquired from a variable acoustics classroom
Authors: Peng Zhao , Lau Siu-Kit , Wang Lily M. , Browne Sean , Roy Kenneth P.
Published: April 2012

Room measurements were conducted in a variable acoustics classroom mockup space (epod) at Armstrong World Industries in Lancaster, Pennsylvania, USA. Binaural room impulse responses were measured in the epod using a head and torso simulator. Five reverberation time (RT) scenarios were achieved with various combinations of absorptive wall panels and acoustical ceiling tile. These provided a range of mid-frequency RTs from 0.4 to 1.1 seconds. Three of the five RT scenarios were achieved using two different material configurations to also consider material location effects. For each of the eight material configurations, two student-teacher orientations were tested. One orientation had all desks facing the front of the room across the long dimension of the space, while the other had all furniture facing the front of the room along the short dimension of the space. Binaural impulse responses were measured at nine student positions in the longitudinal orientation and ten student positions in the transverse orientation, both using two teacher positions. This database of 252 binaural impulse responses from a variable acoustics classroom provides realistic test cases rather than simulations. These are being used for acoustic investigations on various topics including effects of classroom furniture orientation or acoustic material arrangements.
Acoustic evaluation of classrooms in China—green campus workgroup
Authors: Browne Sean , Roy Kenneth P. , Li Jerry
Published: April 2012

Armstrong, as a member of the China Green Building Council, has been working with the special subcommittee on Green Campus associated with Tongji University in Shanghai. The goal of this working group is to develop a green rating system for schools including acoustic design/performance in classrooms. In support of this rating development we have been pursuing research on classroom performance relative to meeting the current GB 50118-2010 and future GB 50099-2011 codes for schools. In conjunction with the Green Campus work group 10 schools were identified across China for study with pre/post architectural interventions. In this case a suspended acoustical ceiling was installed and both objective (sound) measurements, and subjective (student & teacher perception) surveys were conducted. Additionally it was desired to develop an objective assessment of student learning performance with changes in acoustical design and this was addressed through a joint development program with the University of Nebraska. Current results from these school evaluations are being presented.
The use of multi-microphone measurements of directional and random incidence acoustical coefficients
Authors: D'Antonio Peter , Rife Brian
Published: April 2012

This paper will review the use of multiple microphones in the measurement of the normal incidence absorption coefficient, ISO 10534-2, the random incidence absorption coefficient, ISO 354, the scattering coefficient, ISO 17497-1 and the diffusion coefficient, ISO 17497-2. Multiple microphones are used to quadruple the plane wave frequency range providing a bandwidth from 63 Hz to 4000 Hz in a single 150 mm square impedance tube. Random incidence measurements are accelerated by simultaneously measuring 12 impulse responses from two speakers and 6 distributed microphones. Scattering coefficient measurements can be very time consuming, due to the fact that at least 72 MLS averages are required per rotating table revolution. By using the dual source and simultaneous 6 microphone measurement technique, measurement times are reduced from 43 minutes to roughly 4 minutes for a 3 sec MLS stimulus. Diffusion coefficient measurements are greatly accelerated by simultaneously measuring 32 scattered impulse responses for a given angle of incidence. The process utilizes 32 fixed microphones 5 degrees apart, 32 MOTU preamps and an MLS stimulus. The 32 recorded scattered signals are deconvolved with the MLS stimulus to determine the 32 impulse responses from which polar responses and the diffusion coefficient are calculated.
Force estimation and prediction from time-varying density images
Authors: Jagannathan Srinivasan , Horn Berthold , Ratilal Purnima , Makris Nicholas
Published: April 2012

We present methods for estimating forces which drive motion observed in density image sequences. Using these forces, we also present methods for predicting velocity and density evolution. To do this, we formulate and apply a Minimum Energy Flow (MEF) method which is capable of estimating both incompressible and compressible flows from time-varying density images. Both the MEF and force-estimation techniques are applied to experimentally obtained density images, spanning spatial scales from micrometers to several kilometers. Using density image sequences describing cell splitting, for example, we show that cell division is driven by gradients in apparent pressure within a cell. Using density image sequences of fish shoals, we also quantify 1) intershoal dynamics such as coalescence of fish groups over tens of kilometers, 2) fish mass flow between different parts of a large shoal, and 3) the stresses acting on large fish shoals. IEEE Transactions on Pattern Analysis and Machine Intelligence 33(6), pp. 1132-1146 (2011)
An open system for intravascular ultrasound imaging
Authors: Qiu Weibao , Chen Yan , Cheng Wang Fai , Yu Yanyan , Tsang Fu Keung , Dai Jiyan , Zhou Qifa , Sun Lei
Published: April 2012

Cardiovascular disease is the main causes of morbidity and mortality due to lumen stenosis and atherosclerosis. Intravascular ultrasound (IVUS) is able to delineate internal structures of vessel wall with fine spatial resolution. However, IVUS is insufficient to identify the fibrous cap thickness and tissue composition of atherosclerotic lesions, the key factors to stage atherosclerosis and determine appropriate treatment strategies. Currently, novel techniques have been developed to determine tissue composition, which require an open IVUS system to accommodate these techniques for comprehensive plaque characterization. This paper presents the development of such an IVUS system with reconfigurable hardware implementation, programmable image processing algorithms, and flexible imaging control to support an easy fusion with other techniques to improve the diagnostic capabilities for cardiovascular diseases. In addition, this IVUS utilized a miniaturized ultrasound transducer constructed by PMN-PT single crystal for better piezoelectric constant and electromechanical coupling coefficient than traditional PZT ceramics. Testing results showed that the IVUS system could offer a minimum detectable signal of 25μV, allowing a 51dB dynamic range at 47dB gain, with a frequency range from 20MHz to 80MHz. Finally, phantom imaging and in vitro vessel imaging were conducted to demonstrate the performance of the open system for IVUS applications.
Acoustic metamaterials with negative parameters: a multiple scattering approach with examples
Authors: Sánchez-Dehesa José , García-Chocano Victor M. , Gracià-Salgado Rogelio , Cervera Francisco , Torrent Daniel
Published: April 2012

A homogenization method is here developed in the framework of multiple scattering. The method will be described and the resulting semi-analytical formulas are employed to solve several examples in which the effective parameters of acoustic metamaterials are negative. We also present the experimental realization of a quasi two-dimensional acoustic metamaterial with negative bulk modulus. The metamaterial consists of a hexagonal array of cylindrical boreholes. Experiments are performed using a two-dimensional waveguide where a slab of seven layers has been fabricated and characterized to extract the effective dynamical parameters. It is demonstrated that, at the frequency region were the bulk modulus is negative, the impinging wave is totally reflected and the pressure amplitude exponentially decreases inside the slab. The skin-depth effect has been also studied as a function of the frequency. The data are well supported by band structure calculations and by the homogenization method developed in the framework of the multiple scattering theory. Work supported by ONR and MICNN (Spain).
Mode hybridization at subwavelength scale in acoustic metamaterials
Authors: Cheng Ying , Liu Xiaojun
Published: April 2012

The artificial acoustic metamaterials consisting of subwavelength resonator elements can exhibit properties beyond those found in nature. These unique properties were described by effective media approximation theory, which treat the response as the averaged effects of the individual element's resonance response and ignore the coupling interactions between the elements. This paper reports the mode hybridization at subwavelength scale in acoustic metamaterials composed of single-slit Helmholtz resonator arranged in two-dimensional square lattice with twist angle between adjacent elements in ΓX direction. The dispersion curves and the transmission spectra demonstrate that the strong interactions between elements are not negligible when phi=180 degree and could lead to novel coupled resonance modes which do not exist in uncoupled metamaterials of phi=0 degree. The adjunct elements oscillate in-phase for the symmetric hybridization mode and out-of-phase for the anti-symmetric mode. In addition, the hybridizations are very sensitive to the twist angle, which could be indispensable in tuning the transmission. The results may be used to develop novel metamaterials and functional acoustic devices in the future. Acknowledgements: This work was supported by the National Basic Research Program of China (2012CB921504), National Natural Science Foundation of China (11074124, 11104139, and 10904052), and Jiangsu Provincial Natural Science Foundation (BK2011542).
Animations and visualizations of teaching and learning building acoustics for civil engineers
Authors: Abidin Akasah Zainal , Ng Chiew Siah
Published: April 2012

Building acoustics is becoming one of the important considerations in the design of a building. Thus it is of utmost importance to have competent designers who are can integrate acoustics needs in the design stage of a building. However, building acoustics is quite a challenging subject to teach and learn. The traditional method of teaching and learning is not the best method to promote a good understanding of the subject matter. Therefore, alternative methods must be found to improve effectiveness in teaching of this subject matter. The purpose of this study is to review existing animations and visualizations tools that have the potential to be used in the teaching and learning of building acoustics. The scope of this study is limited to education of building acoustics for civil engineers. Selected applications were surveyed on their usefulness to engineering educators. The result indicate that Mediacoustic is one of the most suitable animation and visualization tools for teaching and learning of building acoustic. A sample of animation and visualization module was created by using Xara Xtreme 3.2 as addition added-value to existing Mediacoustic. The sample animations provide support in the teaching and learning of building acoustics.
Investigation of building envelop design for effective traffic noise reduction in Hong Kong
Authors: Chiu Chi Chung , Szeto Wing Kwok , Wu Marco Chi Wai
Published: April 2012

Road traffic noise is a major environmental noise problem in the densely populated city of Hong Kong. The Government of Hong Kong is committed to address the problem and has adopted a series of proactive actions to tackle the problem. Due to the compact cityscape of Hong Kong with major roads running near high-rise residential buildings, besides the more conventional form of measures such as land use planning, roadside barrier and enclosure, innovative form of building envelop design is considered worth exploring. This paper will present investigations for effective traffic noise reduction from building envelop design in Hong Kong. Initial laboratory investigation of insertion loss of various building envelop designs, including different forms of plenum windows and window designs has been conducted. The laboratory investigation is the first step. Further study on building envelop design for practical application would be the next step. The innovative feature would have the advantage of providing considerable amount of noise reduction and a comfortable open-window environment at the same time to the residents.
(R)Evolution in vehicle acoustics—sound design, warning signals and quiet cities
Authors: Genuit Klaus
Published: April 2012

The increasing electrification of the powertrain offers the unique opportunity for complete new sounds with respect to vehicle interior sound and exterior noises after an era of 125 years of combustion engine. With this expected development noise affected persons in urban areas hope for quiet cities and a better quality of life in general. In particular, the creation and preservation of quiet zones in cities is a special focus in European noise policy exploiting the potential of electric vehicles. However, with the expected engine concepts changes - besides the hopes - several conflicts and problems are seen. These concerns are related to apparent technological problems (infrastructure, costs, range limitations) as well as to noise issues probably leading to an decrease of pedestrian safety. This has caused a general demand for acoustical warning signals for quiet (electric) vehicles to alert blind and visually-impaired persons. Are the concepts recently argued really well-thought-out and sustainable? Recent and potential future sound developments are highlighted from different perspectives. Here, from the constituting frame of reference regarding public opinion, automotive manufacturers' considerations, legislative initiatives and political actions the potential design of electric vehicle sound is discussed.
Use of phononic materials in microfluidic & lab-on-a-chip manipulations
Authors: Cooper J. M.
Published: April 2012

The development of microfluidic systems is often constrained both by difficulties associated with the chip interconnection to other instruments, and by mechanisms that can enable fluid movement and processing. Surface acoustic wave (SAW) devices have previously shown promise in allowing samples to be manipulated, although designing complex fluid manipulations involves the generation of mixed signals at multiple electrode transducers. We now demonstrate a new and simple interface between a piezoelectric SAW device and a disposable microfluidic chip, involving the use of phononic structures, to shape the acoustic field. Such phononic structures can be designed in such a way that the interaction of the fluid within the chip structure is dependent upon the acoustic frequency, providing a new method to programme complex fluidic functions into a microchip. We demonstrate applications in biological sensing involving enrichment enrichment of cells, lysis, PCR and sensing, exploring the application of this chip based technology to Developing World Diganostics.
Enhanced surface acoustic wave atomization via amplitude modulation
Authors: Qi Aisha , Rajapaksa Anushi , Friend James , Yeo Leslie , Chan Peggy
Published: April 2012

Recent developments in the miniature chip-based microfludic nebulization platform utilizing surface acoustic wave (SAW) atomizer for inhalation therapy offers distinct advantages over other conventional nebulizers. Such efficient hand-held nebulizer system also requires the optimization of the usage of available power systems in the simplest manner. Here, amplitude modulation (AM) is presented as a simple yet effective means of optimizing the power requirement. SAWs are nano meter order amplitude acoustic waves that originate as a result of the application of an alternating current onto a pair of single-phase unidirectional transducers patterned on a piezoelectric substrate. The effect of the AM at modulation frequencies of 500 Hz, 1 kHz, 5 kHz, 10 kHz, 20kHz and 40 kHz sinusoidal signals, on shear-sensitive biomolecules such as plasmid DNA and antibody molecules are shown to be minimal. Energy savings of around 40% can be obtained with more efficient atomization achieved with AM less than 10 kHz. Together with these advantages, AM having little effect of the mean aerosol diameter; particularly important when therapies are to be targeted for the deep lung regions, holds great promise for its use in the SAW nebulizers for non-invasive inhalation therapy. Acknowledgements are dedicated to Asthma Foundation Victoria (Australia).
Fast measurement system and super high directional resolution head-related transfer function database
Authors: Yu Guangzheng , Liu Yu , Xie Bosun , Zhong Qizhu
Published: April 2012

Head-related transfer functions (HRTFs) describe the acoustical transmission process from a point sound source to two ears in the free field. They are vital to the researches of binaural hearing and virtual auditory display. Measurement is the most important approach to obtain HRTFs, but it is time-consuming. To accurate HRTF measurement, a computer-controlling measurement system is designed. The system consists of multiple sound sources at different elevations with a finest interval of 5° and a horizontal turntable with an azimuthal resolution of 0.1°. It is able to work in non-anechoic environment and suitable for both mannequin and human subject measurement. A practical example indicates that the system allows for measuring far-field HRTFs at 493 source directions within half an hour. By using the system, a super high directional resolution HRTF database for KEMAR mannequin is established. The database includes 3889 pairs of head-related impulse responses (HRIRs, the time domain counterpart of HRTFs) at distance of 1.0 m, elevation interval of 5° (from -45° to 90° ), and azimuthal interval of 2.5°. Each HRIR is 1024-point length at 96 kHz sampling frequency and 24-bit quantization. The database is applicable to the research on binaural hearing and virtual auditory display.
Inversion of temperature vertical structure by ocean acoustic tomography data in the Luzon Strait
Authors: Lin Ju , Kaneko Araka , Taniguchi Naokazu , Wang Huan , Gohda Noriaki
Published: April 2012

Luzon Strait is the key channel which connects the western Pacific and the South China Sea(SCS). It is very important to monitor the exchanges of materials and energy between the western Pacific and the SCS, which are caused by the Kuroshio and eddy's variability. The Kuroshio can intrude into the SCS through the Luzon Strait in various manners and significantly affects the oceanic variability of the SCS. A deep-sea acoustic tomography experiment was conducted at the northern part of the Luzon Strait during April 2008 to October 2008. Three 800Hz acoustic systems were deployed at depth about 800m on the subsurface mooring line, and the distance between the systems was about 40km. The four-month reciprocal acoustic transmission data between a pair systems were successfully obtained. The three groups of acoustic arrival peak were distinctly separated. The temperature vertical structure along the transmission line are inversed by using the Matched-Mode Processing method. The inversion results are in good agreement with the temperature field observations and HYCOM results. The 17-day and 23-day period signals are found in the inversion result, which correspond to the frequency of occurrences of cold eddy in the Luzon Strait. (Work supported by NBRPC 2007CB411803, NSFC 41176033 and ONR)
The Ethiopian lyre Bagana. An ethno-acoustical study
Authors: Weisser Stephanie , Hermand Jean-Pierre , Ren Qunyan
Published: April 2012

The Ethiopian lyre bagana is usually finger-plucked and monodic, with a skin soundboard and ten gut strings tuned to low-frequency pitches (ca 50-150 Hz). Its most important sonorous characteristic is its buzzing sounds, produced thanks to leather pieces placed between each string and the wide bridge. This study is based on a corpus of sounds produced by eight different instruments played by a virtuoso master and recorded in situ with and without the leather pieces. The sounds have been analyzed namely through calculation of several timbre descriptors based on time-domain, sinusoidal harmonic model and short-time Fourier transform representations. These results have been confronted with ethnomusicological analyses of the repertoire and the socio-cultural aspects of the bagana, in order to understand how the sound qualities are dealt with by the players. These joint analyses show that the very distinctive buzzing quality of the bagana sounds can be linked with auditory roughness and inharmonicity descriptors (indicating that it is not due to noise but rather to quasi-harmonic components) while the significant timbre variation between sounds is mostly due to differences in string quality, location of the leather piece on the bridge and musicians' search to produce longest possible duration.
Vibrotactile music systems for co-located and telematic performance
Authors: Egloff Deborah , Braasch Jonas , Robinson Phil , Van Nort Doug , Oliveros Pauline , Krueger Ted
Published: April 2012

Building on previous findings, the project reported here expands on the idea of how the modality of touch contributes to the sensory perception of sound in the presence of vibro-tactile events. The SenseAble1.0, a vibrotactile interface, was developed to transform the auditory parameter space into one that is adequate for haptic perception by the means of eight individually controllable actuators and machine learning algorithms. Due to the process of sensory substitution, people with hearing impairments can use the vibrotactile display to “listen” to music and perceive exterior acoustic stimuli through the sense of touch. A psychophysical pilot study investigated (i) frequency discrimination and pitch direction as well as (ii) interval size recognition of the haptic modality, and (iii) adaptation effects of the somatosensory system. Live performances using the SenseAble as a vibrotactile music system illustrate to what extent musical communication between ensemble members and a hearing-impaired musician is possible. A new prototype with enhanced spatial resolution properties for perceiving vibrotactile stimuli will be introduced as well. It was designed to improve the usability of sensory substitution systems in real and virtual environments and to maximize the efficiency of co-located and telematic performances in terms of musical communication and interaction.
The latest development and application of noise mapping in Hong Kong
Authors: Law Chi Wing , Lui Aaron Shiu Wai , Yeung Maurice Kwok Leung
Published: April 2012

In recent years, there has been dramatic enhancement of computation power, rapid development in Geographic Information System (GIS), three-dimensional (3D) computer graphic and virtual reality technology. Digital topographic and mapping data are also widely available and ultilised for various applications. This had facilitated the rapid advancement in road traffic noise assessments and data presentation. Two-dimensional (2D) and even 3D noise mapping over a large geographical area has now become a much more manageable task. Hong Kong has seized the opportunity in developing advanced 3D noise modelling techniques and noise mapping in support of it's policy evaluation and formulation initiatives. State of the art 3D GIS tools, interface applications with large scale noise modelling software, sophisticated information technologies for data streaming and rendering were tried out in Hong Kong. 3D noise models were presented in meeting and uploaded to web site for consultation with local residents to encourage public participation. Also, the techniques were employed to more accurately determine the noise exposure of the population, the eligibility and overall benefits of applying low noise road surface to road sections in a large area, the determination of noise exposure of residents in support of social survey.
Design and implementation of urban traffic noise mapping system
Authors: Feng Tao , Li Nan , Liu Bin , Hu Wencheng
Published: April 2012

The noise mapping system is a best tool for environment noise controlling, as it can provide a graphical illustration of sound exposure levels in a region for the policy- maker. In urban construction planning, land-use definition and noise environment impact assessment, the noise map has been proved very useful for its efficiency. According to the application requirements of traffic noise prediction model, the CATNMP (Computer Aided Traffic Noise Mapping Platform) has been designed and analyzed in details. The key techniques of algorithm and procedures involved are studied and implemented. An open source topological software package of JTS is used for the development of CATNMP based on GIS data. The traffic noise prediction model is performed with the aid of the computer software system, and a noise map is drawn out. In order to improving the computation efficiency, the distributed computing technique has been implemented in the CATNMP. Finally, the road traffic noise levels in a demonstration area of Beijing city are predicted using the CATNMP and a noise map is drawn for illustration and evaluation of environmental noise. The result shows that the CATNMP can provide an efficient analytical tool for the environmental evaluation of traffic noise, and also technical bases for regional noise emission management.
New town planning—noise mapping tools to facilitate evaluation of noise exposure on different traffic management concepts
Authors: Cheung Tsz Hin (Laurent)
Published: April 2012

In terms of development of modern city, there is always a great requirement on the long-term housing demand, in particular for the strategic New Development Areas (NDA) in New Territories (NT) of Hong Kong. A cross-district traveling for work is a common practice, and there is also a high percentage of Heavy Goods Vehicle (HGV) for logistic goods arrangement. In order to maximize the development potential and to guarantee a noise disturbance free ambient to the intake population, noise mapping tools is therefore selected as an evaluation tools in accordance with 2002/49/EC Directive. Traffic management concepts on (1) road against rail and (2) restricting of HGV to certain trunk roads were tested, and the pros and cons have been evaluated. The general 24-hour flow patterns of roads and rail have been discussed, and these flow natures would have great influence on the Lden and Lnight values. The difficulties and sensitive issues anticipated in the noise mapping exercises have been generally discussed which would be useful for reference.
The benefits of bilateral and directionally selective auditory prostheses
Authors: Culling John , Jelfs Sam , Talbert Alice , Backhouse Steven
Published: April 2012

Both binaural hearing and directional microphones can improve understanding of speech in background noise if the sources of the speech and noise are spatially separated. We used a model of spatial release from masking [Jelfs, et al. (2011). Hear Res. 275, 96-104.] to predict the benefits of bilateral prostheses, directional microphones and head orientation. The model predicts large benefits of each of these factors. Measurements using selected spatial configurations in both normally hearing listeners and unilateral cochlear implantees confirmed the model's predictions. The reception thresholds for bilateral implantees were inferred using mirror-image spatial configurations to be at least 18 dB better than unilateral implantees in certain situations. Expected effects of directional microphones and head orientation were assessed through modelling spatial release from masking in a virtual restaurant situation. The model predicted marked differences between different seating positions, but in most locations, both moderate head rotations and directional microphones offered substantial benefits. Use of directional microphones generally offered larger benefits than head rotation, but there was little benefit from their combination. The addition of reverberation elevated predicted thresholds and reduced all of these effects.
The effects of temporal envelope confusion on release of masking
Authors: Nie Yingjiu , Nelson Peggy , Davies-Venn Evelyn , Svec Adam
Published: April 2012

Widened auditory filters in hearing impaired (HI) listeners may force them to rely more on temporal envelope (TE) cues when listening to speech. We propose that reduced masking release in HI listeners may be partially due to the confusion of the TE's of the masker and target. The current study investigates HI listener's comprehension of low- or high-pass vocoded spondees in the presence of fluctuating and stationary background noise. The spectral relationship of the target and masker was systematically varied from greater to no spectral overlap; the TE's of the masker and target were varied in similarity along two aspects — amplitude-modulation rate and shape. Preliminary data have shown the TE confusion in some HI impaired listeners results in speech understanding scores that are poorer in the presence of fluctuating noise (at a rate of 4Hz) than when the stationary noise is present. On the other hand, another group of HI listeners has demonstrated masking release. The effect of TE confusion of speech-envelope -shaped noise for understanding vocoded spondees will be discussed. Work is supported by NIH DC008306 to PB Nelson
The neural basis for energetic and informational masking effects in speech perception
Authors: Scott Sophie , Evans Samuel , McGettigan Carolyn , Rosen Stuart
Published: April 2012

Functional imaging studies of speech perception have revealed extensive involvement of the dorsolateral temporal lobes in aspects of speech and voice processing. In the current study, fMRI was used as a functional imaging method to address the perception of speech in different masking conditions. Throughout the scanning experiment, subjects were directed to listen to a female talker with whom they had been familiarized previously. In addition to the acoustic noise generated by the scanner, different kinds of masking sound were also presented diotically, at SPL levels determined by pilot testing. The masking sounds were signal correlated noise, spectrally rotated speech, and a second female talker. The results show a network of activation in the bilateral temporal lobes, prefrontal cortex and parietal lobes that were commonly activated across all masking conditions. Controlling for the effects of energetic masking, informational masking gave rise exclusively to clusters of activity in bilateral STG, with peak level activations in left anterior-mid STG and posterior STS/STG and right primary auditory cortex. Post-test intelligibility measures were used to reveal greater activation in the left temporal lobe, which was associated with higher performance scores.
Age-differences in the time course of stream segregation in informational masking of speech by speech
Authors: Schneider Bruce A. , Ezzatian Payam , Li Liang , Pichora-Fuller M Kathleen
Published: April 2012

Ezzatian et al. (Lang. Cognitive Processes, 2011) determined thresholds for detecting three target-words(target-words in italics) in semantically-anomalous but syntactically-correct sentences (e.g., “A rose could paint a fish”) masked by either speech-spectrum noise or by two other females talkers. When both masker and target originated from the same loudspeaker, speech recognition was independent of word position for the noise masker, but improved as a function of word position for the speech masker, suggesting that informational masking prolongs the time it takes to perceptually segregate the talker from the competing speech. Spatially separating the masker from the target sentence removed this word-position effect, as did vocoding the masker, presumably because both operations permitted more rapid segregation of the target from competing speech. The older adults in this study displayed the same pattern of results as the younger adults in Ezzatian et al. when both target and masker were presented over the same loudspeaker. However, in older adults, the word position effect found for the two-talker masker remained after either spatial separation or vocoding. This suggests that the segregation of speech from speech is more “sluggish” in older than in younger adults. Supported by Canadian Institutes of Health Research.
Speech rate influences categorical variation of English flaps and taps during normal speech
Authors: Derrick Donald , Gick Bryan
Published: April 2012

This research demonstrates that North American English speakers with faster syllable iterance rates are more likely to produce reduced /t/ and /d/ as taps, which have two directions of motion, than flaps, which have one. Using B/M mode ultrasound to capture tongue motion direction, coupled acoustic recordings to capture syllable speed, we identified categorical variants of flaps and taps produced by 18 speakers and compared the average likelihood of each variant in relation to the rate at which speakers can repeat `ta'. Faster iterators produce more alveolar taps in single flap phrases (e.g. `autumn), and double flap phrases (e.g. `edit a'). Alveolar taps require more changes in direction of tongue motion, and are often produced to avoid articulatory conflicts with neighbouring vowels. The results support an argument that individual variation in flap/tap production is partly due to a motor skill constraint limiting cycles of tongue motion, weighed against avoiding articulatory conflict. Currently a second experiment, testing whether changing actual speech rates will generate categorical shifts in flap variant production, is in progress. Preliminary results are expected by the conference date.
Influence of medialization depth, implant shape, and implant stiffness in medialization thyroplasty
Authors: Chhetri Dinesh , Zhang Zhaoyan
Published: April 2012

Medialization thyroplaty (MT) is a widely used treatment modality for vocal fold paralysis. The goal of MT is to improve glottal closure, especially as viewed from the superior surface, by surgically placing an implant in the paraglottic space. However, phonatory improvement from the MT procedure is variable. In this study, an excised larynx model was used to investigate the effects of the following ML implant parameters on laryngeal acoustics, aerodynamics, and vibration: medialization depth, medial surface shape of implant, and implant stiffness. Phonation threshold pressure and flow rate, H1-H2, spectral slope, and high-speed recordings of vocal fold vibration were measured as the implant parameters were varied. The relative importance of the implant parameters (depth, shape, and stiffness) to phonatory improvement and the clinical implications will be discussed.