bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoacoustic measurement of the optical absorption spectra of dark or turbid media
Authors: Birtill David , Shah Anant , Jaeger Michael , Bamber Jeffrey
Published: April 2012

A photoacoustic (PA) spectroscopy system has been built to study small samples, particularly the differences between the PA spectra of oxygenated and deoxygenated blood, and various PA contrast agents, with view to optimising the indentifying these media, in clinical PA images. Short (ns) pulses of light from one of two OPO lasers are delivered into a 1mm diameter cylindrical sample holder. The wavelength is scanned over the range 400-700 nm or 690-950nm (depending on laser used) using a different pulse for each wavelength. Sensitive measurement of the thermoacoustic pressure wave energy emitted from the end of the sample, which acts like a disc-shaped piston source, is facilitated by placing it at the focus of a strongly focused ultrasound transducer. The resulting optical spectra are corrected for some system variables, such as the wavelength-dependent laser energy. Further corrections are planned, so that the measurement is truly of optical absorption coefficient at each wavelength. Even without these additional corrections however, the measured PA spectra of oxygenated blood and gold nano-rods strongly resemble their published optical absorption spectra. In addition to its intended use this system may have applications as a laboratory spectrophotometer, suitable for use with optically dark and turbid media.
Importance of temporal periodicity on Mandarin tone perception of cochlear implant recipients
Authors: Yuan Meng , Sun Jin , Chen Youyuan , Feng Haihong
Published: April 2012

Cochlear implants (CIs) were designed primarily to enhance the speech perception of western persons with bilateral sensorineural deafness. The CI technology used in the current commercial devices, in terms of both hardware and software, didn't focus on the delivery of tone or pitch related information. It's known that lexical tone is important to Mandarin-speaking people. To better encode pitch-related information, the current study will investigate the effect of temporal envelope periodicity to Mandarin tone perception of CI recipients. Temporal periodicity from each frequency band is manipulated corresponding to the fundamental frequency (F0) of the speech signal. Psychophysical experiment was carried out to evaluate the Mandarin tone perception performance of CI recipients in quiet and noisy conditions. Test materials were monosyllabic and disyllabic Chinese words with four different tones. Experimental results showed that F0-related coding on temporal periodicity can improve the Mandarin tone perception ability of CI recipients. It is indicated that new speech processing strategy should be developed for better tone perception of Chinese CI recipients. This work is supported by National Natural Science Foundation of China (11104316), and Shanghai Natural Science Foundation (11ZR1446000).
Real-time sound source localization based on multi-resolution scanning in frequency domain
Authors: Hayashida Kohei , Morise Masanori , Nishiura Takanobu , Yamashita Yoichi
Published: April 2012

Robust speech recognition is necessary for realizing useful speech interfaces. A microphone array is an effective item at capturing distant-talking speech with high-quality in noisy environments. It captures the target speech by localizing a talker and steering the directivity. These processing is usually executed in each frequency. For realizing useful speech interface, these processing must be finished in real-time. In the research into sound source localization, various methods have already been developed, and these methods localize a sound source based on acoustic space scanning by fixed resolution in each frequency. Therefore, calculation time is increased, and the real-time processing is difficult in higher spatial resolution. To overcome this problem, we proposed the localization method based on multi-resolution scanning in frequency domain. The lower frequency band has lower spatial resolution, and the higher frequency band has higher spatial resolution. The proposed method localizes the sound source by lower spatial resolution in lower frequency band and higher spatial resolution in higher frequency band. Therefore, the proposed method can reduce the calculation time without degrading the localization accuracy. The experimental results in noisy environment indicated that the proposed method could reduce the calculation time and could achieve the real-time sound source localization.
Study on mechanical feedback of hearing aids using maximum length sequence method
Authors: Cui Jie , Ge Yongjia , Han Xiaoli
Published: April 2012

Mechanical feedback is one of reasons causing hearing aids to howl, therefore the mechanical feedback problems of behind the ear (BTE) hearing aids was investigated by the maximum length sequence (MLS). The realtime data transmission was set up between a BTE digital hearing aid and a computer. The feedback path form the input port of receiver to the output port of microphone was measured with different input magnitude of receiver, in order to investigate the effect of mechanical feedback on the whole feedback path. The experience results verified the availability of the method.
A novel F0 estimator for pitch enhancement in cochlear implant
Authors: Hu Haiyang , Yuan Meng , Meng Qinglin , Feng Haihong
Published: April 2012

Current experimental Cochlear Implant (CI) sound processing strategies like F0mod [Laneau, et.al., 2006], which aim to improve the pitch perception of CI subjects, amplitude-modulate the envelope of each frequency channel by the fundamental frequency (F0) of the speech sound. Due to the hardware limitation of CI devices, typical F0 estimation algorithms are too complex to be implemented. Low-complexity and accurate F0 estimator will be necessary for such manipulation. This study uses the Summary Auto-Correlation Function (SACF) to extract F0. The new pitch estimator was simulated and compared with typical algorithms that estimate F0 before the sub-band filtering. By the use of SACF, the new estimator reduces the computation load significantly and preserves good F0 estimation performance. # This work is supported by National Natural Science Foundation of China (11104316), and Shanghai Natural Science Foundation (11ZR1446000).
Passive localization using flexible hydrophone array
Authors: Chen Lijun , An Liang , Gao Xiang
Published: April 2012

Localizing a radiated acoustic source in shallow water precisely is a difficult problem. To achieve this goal, a large aperture between hydrophones should be considered. But a large and rigid array is not convenient when used by ship. Here a flexible hydrophone array is designed to solve this problem. The position of each array hydrophone is randomly placed. Spherical interpolation method is used to estimate the position of acoustic source. This method need precise 3-D coordinates of each hydrophone to estimate 3-D coordinates of the source. In this paper a new method is derived to estimate the coordinates of each hydrophone. Computer simulation is conducted to analysis the performance of passive localization algorithm using the flexible array. Factors such as time-delay, hydrophone coordinates, and array shape, which affect the localization performance are discussed. Lake trial results are presented and show that the experiment results agree highly with the simulation results.
Hybrid geoacoustic inversion scheme with an equivalent seabed model
Authors: Li Zhenglin , Zhang Renhe
Published: April 2012

Acoustic propagation in shallow water is greatly influenced by the properties of the bottom. The purpose of geoacoustic inversion is estimation of ocean bottom acoustic parameters such as sediment sound-speeds, densities, and attenuations from measured acoustic fields. It is a helpful supplement to direct measurements. Especially, geoacoustic inversion could give low frequency attenuation, which cannot be measured by coring the sediment. Therefore, it has been paid much attention in recent years. A hybrid geoacoustic inversion scheme, which combines several inversion methods together to invert for the bottom parameters, has been proposed based on the fact that the bottom acoustic parameters have different sensitivities to the different physical parameters of acoustic field. This inversion scheme could avoid the problem of the multiple solutions, which are often companied with some geoacoustic inversion methods. The validity of the inversion scheme is verified in a series of sea experiments at different sites. The inverted bottom parameters could be used to forecast the sound propagations and distinguish the atlas marked bottom type quite well. The mapping relation between the sediment types and the acoustic parameters are also given. [Work supported by the National Natural Science Foundation of China under Grant No. 10974218 and Grant No. 10734100]
The relationship between normalmode interference structure and waveguide invariant
Authors: Fuchen Liu
Published: April 2012

In shallow water, waveguide invariant describes the dispersive characteristics of the filed.It relates the normal group slowness and phase slowness of normal modes.In this paper, waveguide invariant changes with normal mode and interference patterns difference are researched. the relationship formula between waveguide invariant and horizontal wavenumber of normal mode is deduced, which is valided by comparision between theorical value with theorical formula with the value from new formula. Correspondingly, the conclusion is drawn that waveguide invariant is decreasing with horizontal wavenumber decreasing, with is also valided by simulation.
Fluctuation of acoustic signals due to internal waves in the East Sea of Korea
Authors: Hahn Jooyoung , Park Joung-Soo , Kim HyoungRok , Chon Woogeun , Lee Haksue , Na Young-Nam
Published: April 2012

This study attempts to investigate the fluctuation of underwater acoustic signals due to internal waves (IWs) off the east coast of Donghae, Korea. Sea experiment was performed with thermistor strings, a sound source, and an array of hydrophones. Based on the thermistor string data, the IWs have characteristics of typical periods of 10-20 minutes, amplitudes of 10-20m, and a duration of 1-2 hours. The IWs were analyzed as they moved from offshore to the coast at a speed of 70 cm/sec. Underwater acoustic signals (CW 80 - 800Hz) also show obvious energy fluctuations with the IWs. Through an analysis of these acoustic signals, fluctuations of periods of 15 minutes are located in time domain. As mixed layer depth varies with time, it may cause travel time difference of acoustic signals. This travel time differences causes fluctuation of acoustic signals in range-independent stratified ocean structure. The spectrum characteristics of the acoustic signals show the possibility that acoustic waves may react to the IWs through mechanisms such as mode coupling and travel time fluctuation.
Baseband code estimation for underwater acoustic phase encoding signal
Authors: Wang Xiaoyan , Fang Shiliang , Wang Li
Published: April 2012

A method based on phase jump is proposed in this paper to solve the problem of the baseband code extraction from the underwater acoustic phase encoding signal under non-cooperative conditions. Phase estimation is conducted to the baseband signal, which is demodulated from the received signal according to the estimated carrier frequency. Besides, data smoothing processing is performed twice to reduce the noise effect. Then the baseband code can be estimated by using phase jump of the baseband signal. In practical application, the code sequence is difficult to directly estimate by using the baseband signal waveform due to the distinct amplitude distortion caused by the complexity of underwater acoustic channel. However, the approach based on phase jump is not sensitive to the amplitude fluctuation. So it is especially suitable for the estimation of baseband code form the underwater acoustic phase encoding signal. Computer simulations and experiments in the lake verify the feasibility of this method.
The improved methods and results of HRBSSS for Mapping the Deep Sea Bottom
Authors: Liu Xiaodong , Zhu Weiqing , Zhang Fangsheng , Zhang Dongsheng , Xu Gaofeng
Published: April 2012

High resolution bathymetric sidescan sonar (HRBSSS) is designed by the Institute of Acoustic, Chinese Academic of Sciences (IACAS). HRBSSS have used the technique of direction of arrival (DOA) estimation. It can work near the sea bottom and mapping the deep sea bottom, and get the high resolution bathymetry and sidescan map, concurrently. HRBSSSs have been mounted on the DTA-6000 deep towed body (maximum work depth 6000m) and the Jiaolong HOV (maximum work depth 7000m). In order to upgrading the performance of the system, a new method for improving the depth accuracy on the nadir of the vehicle and an error correct method for minimizing the influence of the inconsistency among the channels have been developed by IACAS. With these method, we have got the good survey results on the area of the seamount (>2000m depth) and on the area of the sea plain (>5000m depth) in the Pacific Ocean in 2011. These methods and results will be introduced in this article.
Reservoir acoustics and its applications
Authors: Wang Xiuming
Published: April 2012

Reservoir is an underground formation with various pores that is able to store oil, water and/or gas, while reservoir acoustics is related to studies and applications of acoustic wave interactions with multiphase porous media. The reservoir acoustics stems from seismic petroleum exploration (including single well imaging, vertical seismic profile, and cross-well tomography), acoustic logging, rock acoustic measurements, sedimentology, digital acoustic signal processing and imaging, and so on, through which it has developed into a comprehensive acoustics branch for the petroleum exploration and exploitation. In this presentation, I will give a comprehensive review for reservoir acoustics and discuss the technical problems in this recently developed acoustics branch with its major applications. This will include the concepts of reservoir acoustics, the research areas of reservoir acoustics, important applications, and future developments. I will focus on the progress of acoustic wave propagation in multiphase porous mediums, time reversal acoustic imaging for seismic data, and hydrostatic pressured fracture detection in enhanced oil recovery using micro-seismics, three-dimensional borehole acoustic well logging. Especially, I will discuss the borehole acoustic mode characteristics for borehole acoustic wavefield representation in complex borehole configurations. Also, I will discuss the applications of borehole acoustic well logging in formation anisotropic identifications, stress evaluations, and so on.
Spatial impressions from late overhead reflections in concert halls
Authors: Hanyu Toshiki , Hoshi Kazuma
Published: April 2012

It is known that not only late lateral reflections but also late overhead reflections contribute to listener envelopment (LEV) which is one of the perceptive factors in the spatial impression of sounds in a concert hall. This paper describes results of psychological experiments which are intended to clarify differences between spatial impressions of the late overhead reflections and that of the late lateral reflections. The results are the following: (1) Late overhead reflections have a different acoustic effect from late lateral reflections. (2) Late overhead reflections increase not only LEV but also overhead sound image (OSI). (3) Late lateral reflections contribute mainly to horizontal listener envelopment (HLEV). (4) If OSI is increased in addition to HLEV, a listener feels vertical listener envelopment (VLEV).
Spatial room acoustics descriptors from a concentric source-receiver array: potential applications for auditoria
Authors: Miranda Luis , Cabrera Densil , Stewart Ken , Martens William L.
Published: April 2012

Electroacoustic transducer arrays, both microphones and loudspeakers, are emerging as promising tools for measuring and evaluating room acoustics – accounting for source directivity and the angular distribution of the received room reflections over time. This study examines the potential of a concentric source-receiver array for characterizing the spatial response of rooms. Using this concept, the acoustic response at a point in a room is represented by a matrix of impulse responses comprising the combined spherical harmonic series for source and receiver. The spatial analysis of this matrix yields the spatial room response for a source of arbitrary directivity and orientation (limited by the spherical harmonic order implemented). The reduction of such data to parameters can be approached in many ways, and this paper considers the mean and standard deviation of diffusivity index for an nth order cardioid source. Measurements from a prototype transducer are presented. In auditoria, this approach could be well suited to the evaluation of acoustic conditions on stage, and should be especially relevant to describing the effect of acoustics on solo performance.
Coupled volumes in concert halls—impact on spatial perception
Authors: Nakajima Tateo , Brooks Todd L.
Published: April 2012

It has long been understood that the use of variably coupled volumes in concert hall design has an impact on room acoustics beyond reverberation and the perception of reverberance. In this presentation, Artec will discuss recent examinations of and experiences in coupled volume halls on spatial perception, both in terms of subjective experience and measured data. Various spatial phenomena experienced by both musicians and audience members will be compared and discussed by the presenter. Artec will further discuss future design considerations related to these new observations in light of previous designs with variably coupled upper volumes and with variably coupled side chambers.
Acoustical considerations for improving spatial impression in designing concert halls
Authors: Jeon Jin Yong , Kim Yong Hee , Jang Hyung Suk
Published: April 2012

One of the major acoustical considerations in designing concert hallsisimproving spatial impressions through providing more early lateral reflections.The lateral energy fraction (LF) and the interaural cross correlation (IACC) are useful measures for assessing design alternatives in a viewpoint of better spatial impression. In this paper, design developing process for improving spatial impression was demonstrated with a concert hall case.In the early design stage, a bell-shaped cross-section with vineyard seating was proposed to enhance the lateral reflections for the audience. The main reflecting surfaces, which were stage enclosure, lateral walls, balcony fronts, and ceiling, were evaluated to optimize the shape and angle for early reflections. The horizontal diffusers were additionally installed for the improving the spatial impression. The validation was performed with computer simulations and 1:10 scale model measurements for the evaluation of the alternatives.
The effects of focussing elements on spatial sound indices
Authors: O'Keefe John
Published: April 2012

Building geometries that focus sound are generally thought to be acoustically deleterious. This despite evidence to the contrary, such as barrel vaulted naves in churches and cathedrals. There are successful concert venues with barrel-vaulted ceilings, notably London's Wigmore Hall and sections of rooms that benefit domed ceilings, e.g. the balcony of Vancouver's Orpheum. The present study experiments with focusing elements in computer models, concentrating on barrel vaulted ceilings above a shoe-box plan. Building on the author's previous experiments with Height/Width ratios, similar studies have been carried out on single and double radius curved ceilings. In terms of spatial impression, a tall narrow shoe-box shaped room benefits from a barrel-vaulted ceiling whose focus (or foci) are appropriately high enough about the listening plane.
Simultaneously monitoring noise and cetaceans in the Ligurian Sea
Authors: Giorli Giacomo , Hughes David , Au Withlow
Published: April 2012

The interest in the effect of anthropogenic noise on marine life increasing rapidly, this is driven primarily by legislations in many countries that noise can be considered to be a pollutant, as for the European Marine Strategy Framework Directive. One particular area of concern has been in the interaction of military tactical sonar and the acoustically more sensitive species of cetacean, in particular the effect on beaked whales. Five ecological acoustics recorders (EAR) buoy having a sampling frequency of 80 kHz and a hydrophone with a flat sensitivity of -193.5 ± 1dB re 1 μPa up to 40 kHz have been deployed in the Northern Mediterranean at a depth of about 850 m in a canyon region known to host a population of Cuvier beaked whales (Ziphius cavirostris). The area is also located in the nearby of different shipping harbors and ferries routes. The utility of the EAR systems is that they simultaneously allow monitoring of noise levels across a wide frequency range while simultaneously allowing assessment of the presence of a range of different species – including Cuvier beaked whale sperm whale and dolphins. Here we discuss the initial results for noise assessment and for cetacean monitoring.
Classification of odontocete using spectral properties of echolocation clicks
Authors: Lu Yang , Klinck Holger , Mellinger Dave
Published: April 2012

The spectral properties of echolocation clicks are investigated for six species' sounds collected from ships and platforms in the North Pacific: bottlenose dolphins (Tursiops truncatus), melon-headed whales (Peponocephala electra), short- and long-beaked common dolphins (Delphinus delphis and D. capensis), Hawaiian spinner dolphins (Stenella longirostris longirostris) and beaked whales (family Ziphiidae). Spectral properties of different frequency bands are compared among the six species and derivatives of spectral slopes and differences between unique spectral peaks and notches are calculated as features to characterize the clicks. Both classification and regression trees (CART) and random forests are employed for species classification. The performance of these methods is compared in terms of complexity and accuracy.
Individual variability of echolocation and diving behavior of Yangtze finless porpoises
Authors: Kimura Satoko , Akamatsu Tomonari , Wang Kexiong , Wang Ding , Li Songhai , Arai Nobuaki
Published: April 2012

Passive acoustic monitoring has been widely applied to observe the presence, movement and behavior of the target species. For quantitative analysis, the acoustic cue production rate of the target animals must be observed in advance. We examined the detailed pattern of biosonar and swimming behaviors of 10 Yangtze finless porpoises (1 female and 9 males) obtained by electronic tags attached to the animals. The click trains produced by the tagged animal were identified out of other animals' vocalizations using bearing angles calculated by the time-of- arrival differences of the sounds between the two hydrophones in the acoustic tag. The number of click trains produced in 10 min did not relate to the body size or sex and varied from 0 to 290. Although deeper the animals dive, faster they swam, the speed or maximum depth of the animals had no correlation with the number of click trains produced or body size. All parameters we examined had no diurnal rhythm but had independent aperiodic variation. The sound production rate without day or night bias is suitable for the quantitative passive acoustic monitoring of this species.
Acoustic estimation of effective gathering range of shipboard fishing light for squid jigging
Authors: Takao Yoshimi , Takahara Hideo , Shikata Takafumi , Namari Susumu , Sasakura Toyoki , Watanabe Toshihiro
Published: April 2012

The effective range of fishing light for the Japanese common squid jigging was investigated using acoustic methods in the Japan Sea on August 21- 24, 2011. The research vessel collected acoustic signals of a sonar and a quantitative echosounder from squid around the jigging boat equipped with metal halide lamps. Digital images of sonar echogram were composed to make maps which can be used to measure locations, sizes, and relative echo intensity of squid school. Behavior of individual squid was observed by an acoustic tag. The receiver was prepared on each vessel. The tag was attached on a fin of squid onboard the research vessel. Total 22 tagged squids were released from the research vessel in three nights and the distance between the vessels at release time ranged from 0.25 to 1.1 nmi. Total 7 squids were received at the jigging boat after 1 - 3 hours from their release. The distance between vessels at release time ranged 0.25 to 0.7 nmi. The squids which were released within 0.5 or 0.6 nmi were received at the jigging boat in every night. From these results, the effective gathering range of the fishing light was estimated to be at least 0.5 nmi.
Measurement of acoustic properties of tissues using ultrasonic tissue imaging system
Authors: Hachiya Hiroyuki , Yamaguchi Tadashi
Published: April 2012

Acoustic properties of living tissues are an important parameter for quantitative estimation of the tissue structure. It is very important to determine the relationship between the physical and the chemical change of tissue structure and the change of acoustic properties. We have developed ultrasonic tissue imaging system (UTIS) to measure the special distribution of acoustic properties at frequencies form 3 MHz to 50 MHz. The speed and attenuation of sound were measured by the noncontact technique based on frequency-time analysis of a reflected pulse response. From rat tissues measurement, The speed of sound in normal tissues varied minimally between individuals and was not related to body weight or age. The relationship between speed of sound and density in normal, fatty and cirrhotic livers can be fitted well on the line which is estimated using the immiscible liquid model assuming a mixture of normal liver and fat tissues. We have also measured the distribution of acoustic properties in human tissues, and obtained relationship between the sound speed and the attenuation of tissue. These findings of the relationship between tissue structure and acoustic structure are used for development of a quantitative diagnosis technique.
High resolution biomedical imaging—multimodal ultrasound microscope and combination with optics
Authors: Saijo Yoshifumi
Published: April 2012

High frequency ultrasound imaging has evolved from classical acoustic microscopy to the multimodal ultrasound microscope which is available for quantitative C-mode, surface acoustic impedance mode and 3D-mode imaging. The evolution has realized both quantitative parametric imaging and easier observation. Quantitative C-mode representing two-dimensional distribution of attenuation or sound speed is realized by frequency-domain analysis of a single pulse by a high speed digitizer. Because the square of sound speed is proportional to the tissue elasticity, sound speed imaging provides biomechanical information of the tissues which is especially important in cardiology and orthopedic surgery. The data also help understanding clinical echo features, especially important in grading of liver fibrosis. Surface acoustic impedance mode without thin-slicing has been applied for imaging of fresh brain tissues and real time observation of high-intensity focused ultrasound procedures. High frequency 3D-mode imaging has visualized 3D structure of sebaceous gland in dermis. Compared with optical coherence tomography which provides higher resolution imaging, ultrasound is superior in the penetration depth and assessment of tissue elasticity. Photoacoustic imaging provides not only morphology but also small blood flow distribution. Both ultrasound and optical methods should develop together to realize high resolution and “gentle” biomedical imaging.
Quantitative ultrasound microscopy imaging of cells
Authors: OBrien William , Auger Thomas , Han Aiguo , Wirtzfeld Lauren
Published: April 2012

Using high-frequency ultrasound, two approaches were used to quantify eukaryotic cell properties. One approach (10-100 MHz) is model-based wherein live cells of known number and volume density are placed in a mixture of bovine plasma and thrombin to form a clot. Backscatter coefficient estimates are modeled against a concentric sphere scattering model to yield cell and nucleus diameters as well as density and speed of cytoplasm and nucleus of Chinese hamster ovary (CHO) and 3T3 fibroblast cells. Estimated cell and nucleus diameters were consistent with direct light microscope measures [CHO cell: 13 microns, nucleus: 6.6 microns and 3T3 cell: 23 microns, nucleus: 13 microns]. For CHO cells, both density and speed of the cytoplasm were less than those of the nucleus. For the 3T3 cells, both density and speed of the cytoplasm were not significantly different from those of the nucleus. The other approach (65-170 MHz) is a direct through-transmission round-trip measure (RF echo reflected from strong reflector), yielding estimates of attenuation and speed of cytoplasm and nucleus of MAT B III mammary adenocarcinoma cell. Speed of cytoplasm was not significantly different from that of the nucleus. The attenuation of the cytoplasm and nucleus were 0.61-0.77 and 0.94 dB/cm-MHz, respectively. [Supported by NIH R01CA111289; l'Ecole Centrale de Lille for TA; Canadian National Science and Engineering Research Council for LAW]
Ultrahigh frequency ultrasonic transducers
Authors: Shung K. Kirk
Published: April 2012

Acoustic microscopy and ultrahigh frequency (UHF) ultrasound microbeam applications require high performance single element transducers from a few hundred MHz to a few GHz. Design and fabrication of such transducers differ drastically from lower frequency transducers. A top- down approach i.e. lapping, grinding and polishing a bulk piezoelectric material to the desirable thickness no longer works. Instead a bottom-up approach i.e., depositing thin layers of a piezoelectric material is preferred. Although ZnO has been the piezoelectric material of choice for many years because it can be easily sputtered in thin films onto a substrate, it however suffers from a low electromechanical coupling coefficient. Better design and piezoelectric materials are sought to enhance the performance of UHF transducers. Thin film PZT, PMN-PT and other novel materials have been shown to offer superior performance. Lensless design may be an alternative to that used in conventional acoustic microscopic transducers.
Ultrasonic C-mode imaging with phase conjugation
Authors: Ohno Masahiro
Published: April 2012

Phase conjugation, or Time-Reversal equivalently, is a technique that produces retro-propagating waves for arbitrary incident waves with their wavefront structures preserved. We have been working to construct a C-mode ultrasonic imaging system that incorporates phase conjugation procedures. This system is composed of a conventional C-mode imager and a phase conjugator working via parametric w-2w interaction in a nonlinear piezoelectric medium. In this paper, some observation results by this system at an ultrasonic frequency of 10 MHz, mostly for thick soft biological samples, are presented. In the transmission imaging mode, images by phase conjugation showed the ultrasonic attenuation distributions that are approximately coincident with the real tissue structures, whereas conventional C-mode images for the same samples showed more complex patterns that reflected both the shape and the attenuation factors of the sample. Some simpler-structured artificial samples made of agarose gels were also tested to study the essential features of this phase conjugate image-forming method.
The life and death of single cells: an acoustic microscopy investigation
Authors: Strohm Eric , Pasternak Maurice , Kolios Michael
Published: April 2012

Changes in cell structure as tumours respond to cancer therapies can be detected using high frequency ultrasound (20-60 MHz). However, it is unknown how single cell variations influence the ultrasound signal as these ultrasound frequencies cannot resolve individual cells. Acoustic microscopy uses ultra-high frequency ultrasound (over 100 MHz) to quantify the structural and mechanical properties of single cells. The backscattered echoes from the cell membrane and substrate were used to determine the thickness, sound speed, density, bulk modulus and attenuation of breast cancer cells undergoing various biological processes, such as mitosis (cell division) and apoptosis (programmed death). Moreover, measurements were made to examine differences between malignant and benign breast tumour cells. Statistically significant changes in the thickness, sound speed and bulk modulus (2%), and attenuation (60%) between malignant and benign cells, and thickness (70%) and attenuation (21%) between cells undergoing mitosis and apoptosis were observed. Differences in bulk modulus (4%) and attenuation (30%) were observed between early and late stage apoptosis, which can be attributed to the irreversible changes in cell structure during cell death. In summary, acoustic microscopy can be used to probe single cells and help understand their contribution to ultrasonic changes in tumours responding to chemotherapy treatments.
An airborne acoustic fiber sensor using fiber Bragg grating with wavelength division coupler demodulating method
Authors: Cheng Jin , Feng Jie , Zhao Longjiang
Published: April 2012

In this paper, we report an airborne acoustic fiber sensor. It consists of a broadband ASE light source, a circulator, a fiber Bragg grating (FBG) with a central reflecting wavelength of 1550nm, a round nickel membrane with a diameter of 9mm and a thickness of 3μm, and a wavelength division multiplexed (WDM) coupler demodulating module. The fiber Bragg grating is bonded to the nickel membrane along the central line with epoxy. The principles of the fiber sensor are described as follows: the sound wave causes the membrane to vibrate and the FBG bonded to the membrane to be bent. The shifts of the central reflecting wavelength caused by FBG bending are modulated by sound waves. The shifts are demodulated by a WDM system with an acoustic signal processing unit. The fabricated fiber sensor shows some advantages, such as water-proof character (about 2m deep under water), easy extending to arrays and easy fabrication procedures. It has widely potential applications in acoustic detection fields.
Efficiency analysis on a piezoelectric micro-machined ultrasonic transducer as a high intensity wave generator in air
Authors: Lee Haksue , Je Yub , Moon Wonkyu , Na Young-Nam , Seo Hee-Seon , Hahan Jooyoung
Published: April 2012

It is difficult to efficiently produce high-intensity acoustic/ultrasonic waves in air with a conventional piezoelectric transducer because of the huge acoustic impedance mismatch between solid-state transducers and air. In this work, the mechanoacoustic efficiency of a thin-plate flexural mode transducer is analytically compared with that of a conventional 1/4ƛ thickness mode vibrator. Radiation and internal mechanical quality factors are applied in the analysis. In the case of the thickness mode piezoelectric vibrator, the radiation quality factor does not depend on design factors, but only on material properties. Consequently, the mechanoacoustic efficiency of the thickness mode vibrator depends only on the material properties, and is less than 3% for most piezoelectric ceramics. For a thin-plate flexural mode transducer, the radiation quality factor can be controlled by the aspect ratio of the thin-plate, which is one of design parameters. Theoretically, the mechanoacoustic efficiency of the flexural mode transducer can be designed to be nearly 100% at the resonance frequency. By experimental analysis, the mechanoacoustic efficiency of the micro-machined transducer was about 65.9%, and the overall electroacoustic efficiency was 58.4% in the resonance. The transducer arrays designed based on this analysis have been successfully applied in parametric array applications in air.
Design and fabrication of a high frequency annular array for medical ultrasound systems
Authors: Peng Jue , Hu Zhenhua , Tang Hu , Wang Tianfu , Chen Siping
Published: April 2012

Most high frequency (>15MHz) medical ultrasound systems are based on single element transducers mechanically scanned. These systems can provide images with excellent resolution. However, single element transducers are often limited by the fixed focal point and small depth of field. High frequency medical ultrasound annular arrays consisting of concentric rings of elements are focused electronically. These arrays are desirable to avoid the fixed focal point of the single element transducers and improve the depth of field. This paper demonstrate an over 10MHz annular array transducer with novel piezoelectric single crystal. This transducer exhibits good energy conversion performance with a very low insertion loss at the center frequency. The transducer is promising for intravascular ultrasonic imaging and other applications. This work was supported by the National Natural Science Foundation of China (Grant Nos. 10904093 and 61031003), the Science and Technology Grant Scheme funds from Shenzhen Government (No. 08CXY-23).
The temperature range limitation of passive, wireless monitoring by surface acoustic wave device
Authors: Wang Hao , Wu Haodong , Shui Yongan
Published: April 2012

There were many studies devoted to SAW passive, wireless temperature monitoring. There are two ways to implement SAW passive, wireless temperature monitoring: through time domain and through frequency domain. Most researches utilized the time domain approach, on behalf its accompanied identification function. For time domain approach, it is necessary to use the phase information for judging the temperature so as to reach enough precision. However, in order to have an exclusive measuring value, there exists a temperature range limitation, which is related to the error for used system, required reliability, the permitted frequency band, and the needed temperature accuracy. It is important to note it when people want to monitor an object in a wide temperature range. In this paper, the relation among the temperature range and the error, required reliability, the permitted frequency band, and the needed accuracy is discussed. Furthermore, a novel method is raised to increase the temperature range under the same conditions. This work is supported by Natural Science Foundation of China under Grant No. 11174205.
Effects of audio reproduction methods on the sense of presence in audio-visual content
Authors: Ozawa Kenji , Obinata Masashi , Kinoshita Yuichiro
Published: April 2012

The sense of presence is crucial for evaluating audio-visual equipment. To clarify the effects of audio reproduction methods on the sense, two experiments were conducted under audio-only and audio-visual conditions. Twelve scenes were recorded with a high-definition video camera while their sounds were recorded using a dummy head. In the audio-only condition, the recorded audio signals were reproduced with headphones by five methods: binaural reproduction with and without the headphone transfer function calibration, binaural reproduction with the joint stereo coding, stereophonic reproduction in which head-related transfer functions from two loudspeakers to the both ears were convolved to the binaural signals, and diotic reproduction in which the left and right channel signals were superimposed. Twenty subjects evaluated each stimulus using a Likert scale. In the audio-visual condition, the same experiment was performed while video signals were reproduced with a 65-inch display. In the audio-only condition, the effect of reproduction methods was significant, i.e. stimuli with the three binaural reproduction methods were evaluated as being higher presence than those with the other two methods. In the audio-visual condition, however, the effect was less prominent. These results suggest that spatial information of audio signals was compensated by visual information. [Work supported by NICT]
Assessment of annoyance caused by different types of construction noises
Authors: Lee Sung Chan , Lee Pyoung Jik , Jeon Jin Yong
Published: April 2012

In the present study, annoyance caused by diverse construction noises was evaluated through surveys and laboratory experiments. A survey with a total of 100 construction workers was carried out to investigate annoyance from construction noises at different construction phases. Then, a number of noises from machinery that were evaluated in the survey as highly annoying were recorded from construction sites in Korea. Recorded construction noises were classified into four groups: stationary, fluctuating, intermittent, and impulsive, according to the temporal, psychoacoustical and spectral characteristics of the noises. A laboratory auditory experiment was then performed in order to quantify the total annoyance caused by individual construction noise and multiple construction noises. From the experiment, synthesis curves were derived for the relationship between noise levels and the percentage of highly-annoyed (%HA) and the percentage of annoyed (%A) for the combined noise sources.
A-weighting the equal loudness contours
Authors: Charbonneau Jeremy , Novak Colin , Gaspar Robert , Ule Helen
Published: April 2012

The standardized equal loudness contours identify the non-linearities of the human auditory system using simple sinusoidal input signals. The graphical illustration of auditory performance trends provides a visual representation of these non-linearities with respect to both frequency and amplitude across the range of auditory perception. Metrics such as the A-Weighting filter approximate one generalized curve shape, in an effort to quantify measured values in a manner that represents the perception of the measured sound. With the release of the ISO226:2003 version of the standard, the most recent version of the equal loudness contours provide an improved contour set with more refined shapes and steeper slopes. The purpose of this study is to investigate the performance of the A-weighting function compared to the updated curves of the equal loudness contours. Included is an examination and discussion of the appropriateness of the continued use of the existing A-Weighting filter. Given the overall un-hyperbolic shape and flattening of the equal loudness contours as the amplitude of the noise increases, the A-weighted results visually identify the areas of weakness associated with a constant filter approach. This visual examination easily identifies the strengths of each approach as well as the deviations from anticipated outcomes.
Annoyance evaluation of interior vehicle motor noise by impulse response method
Authors: Lee Sin-Yeob , Park Buhm
Published: April 2012

In this study, the annoyance of EPS(Electronic Power Steering system) motor noise in a vehicle was evaluated through the anechoic chamber test. Evaluation during actual operation installed in vehicles allows in-situ annoyance tests, but requires a great deal of labor and time. Therefore anechoic chamber test is required to automate the evaluation process under consistent test condition. However vehicle noise test is significantly different from anechoic chamber test from different sound generation and propagation. Due to these discrepancies, the evaluated results among motors open differ between two test results. For consistent test results compared to those obtained from the actual vehicle environment, impulse response of both the vehicle interior and anechoic chamber was measured, and produced a simulated motor noise by using recorded signal in the anechoic chamber. The important peak noises at 1/3 octave bands to take into account of the tonal components were selected for evaluation of its noisiness. From the multiple regression model, the annoyance of motor noise in vehicle using the anechoic chamber test was evaluated.
The complexity of sound quality engineering—only a technical issue?
Authors: Klaus Genuit
Published: April 2012

It is an absolutely essential task to enhance the perceived quality of technical products in order to stand out against competitors in times of a highly competitive market. It is clear that sound quality engineering has changed over time from basic level reduction needs to more complex sound quality design processes taking into account several psychoacoustic quantities. Today, it is very evident that sound level indicators are completely insufficient in describing and predicting perceived sound quality. Nevertheless, it is still an ambitious and challenging task to design product sound adequately, which indicates functionality, high quality, and corporate identity at the same time. To fulfil this task sound quality engineering work must change from a simple technical consideration to an interdisciplinary perspective, where knowledge from engineers, psychologies and sociologists is required. Sound quality is not an inherent product property, it develops when listeners are exposed to and interact with a technical product finally judging on the basis of their experience, expectation and context. Sound quality engineering has to consider these “confounding” variables. The paper will highlight the newest developments in the field of sound quality engineering of technical products. For it, experimental data collected with different test methods and its respective analysis results will be shown and discussed.
A local noise ordinance for relatively small community, population 16,000
Authors: Schomer Paul
Published: April 2012

This paper presents a local noise ordinance developed for a relatively small community with a population of about 16,000. Key features are ease of enforcement by the use, 95 to 99 percent of the time, of simplified methods, with more detailed, rigorous procedures used only when needed (less than 5 percent of the time). When the more complex procedures are used, they are to be performed with qualified personnel and equipment that are external to the township staff. Use of sound level meters is minimized by employment of noise control techniques that depend on more easily measured factors than sound pressure level. Specifically, the ordinance includes such techniques as speed limits (for noise control), distance criteria, time of day, and the criteria “plainly audible,” to reduce reliance on traditional measurements using a sound level meter. The ordinance includes enforcement procedures and qualifications for both the “every day” actions that should be 95 to 99 percent of all of the actions, and the more detailed and precise measurements procedures for the infrequent times that they are needed
Noise regulations and control policy in Taiwan
Authors: Chou Li-chung , Yu Chung-ho , Chen Chien-wei
Published: April 2012

The number of noise complaint cases increased gradually every year in Taiwan. Refer to the annual report, the major noise sources were such as entertainment and business noise, following with noise from construction sites. The high population density and mixed residential and commercial zones caused a lot of noise complaint cases in urban areas. There were also a lot of neighbor noise complaints. In addition, traffic noise with no effective buffer zone caused complaints from the residents along the wayside. In order to solve the various types of noise problems, the Environmental Protection Administration proposed a noise control policy for short-term, mid-term and long-term. This paper will describe the noise control regulation structure and introduce the control policy in Taiwan.