bluuebunny/crossref_metadata_2025 huggingface dataset:
On the importance of room acoustics in multi-microphone speech enhancement
Authors: Gannot Sharon
Published: April 2012

Speech quality might significantly deteriorate in presence of interference. Multi-microphone measurements can be utilized to enhance speech quality and intelligibility only if room acoustics is taken into consideration. The vital role of the acoustic transfer function (ATF) between the sources and the microphones is demonstrated in two important cases: the minimum variance distortionless response (MVDR) and the linearly constrained minimum variance (LCMV) beamformers. The LCMV deals with the more general case of multiple desired speakers. It is argued that the MVDR beamformer exhibits a tradeoff between the amount of speech dereverberation and noise reduction. The level of noise reduction, sacrificed when complete dereverberation is required, is shown to depend on the direct-to-reverberation ratio. When the reverberation level is tolerable, practical beamformers can be designed by substituting the ATFs with their corresponding relative transfer functions (RTFs). As no dereverberation is performed by these beamformers, a higher level of noise reduction can be achieved. In comparison with the ATFs, the RTFs exhibit shorter impulse responses. Moreover, since non-blind procedures can be adopted, accurate RTF estimates might be obtained. Three such RTF estimation methods are discussed. Finally, a comprehensive experimental study in real acoustical environments demonstrates the benefits of using the proposed beamformers.
Cavitation bubble in alcohol aqueous solutions
Authors: Chen Weizhong , Cui Weicheng , Qi Suibao
Published: April 2012

The alcohol, as a surface active agent, plays an important role in sonoluminescence. The violent pulsation of the cavitation bubble makes the sonoluminescence possible. In this talking we report the experimental measurement for the bubble pulsations in alcohol aqueous solutions at different concentration subjected to the excitation of the ultrasound. The results shows that the maximum radius and the bearable intensity of the ultrasound of the bubble decrease with the concentration increasing. At the same time, the compression ratio of the volume goes also into decline as the concentration increases. These results are consistent with the observations of sonoluminescence in alcohol aqueous solutions. And we conclude that the weakened bubble pulsation causes mainly the sonoluminescence darkened in alcohol aqueous solutions. A question about decreasing in the bearable ultrasound intensity of the cavitation bubble in alcohol aqueous solution is still open and worthy of further investigation.
Real-time phase correction for transcranial focused ultrasound surgery
Authors: Jing Yun
Published: April 2012

The skull has been a barrier to transcranial focused ultrasound therapy, because of its strong phase aberration. Previous methods for phase correction are based on numerically solving the wave equation, which outputs the desired phase delay for each transducer element. These methods are typically quite time-consuming. The present method aims to achieve real-time phase correction. This method is based on the Eikonal equation, which is a high frequency approximation to the wave equation. It fully accounts for the refraction in the skull, which is the main contribution to the phase aberration in the skull. Fast marching method (FMM) is used to solve the Eikonal equation. Preliminary results show that, solving the Eikonal equation is over 100 times faster than solving the wave equation by the finite-difference time-domain method. More importantly, a relatively sharp and accurate focus can be achieved in the brain using the present method.
Comparing two acoustics degree programmes in China and UK
Authors: Lam Y.W. , Li F. F.
Published: April 2012

With the current trend of education globalisation, the past decade has seen a tide of student migration and exchanges across the Pacific Ocean, evidenced by a large number of students from Asia-Pacific regions pursuing their university degrees overseas. Comparatives pedagogical studies become timely, especially in niche science and engineering disciplines that tend to have rigorously specified prerequisites that are likely to impose challenges on student exchange and the design of joint programmes. Taking a case study approach, this paper compares syllabi and pedagogical practices in acoustics degree programmes between two representative and reputable institutes in China and the UK, with the aims to promote good practice, suggest necessary harmonisation of syllabi in order to facilitate student exchange and possible exchange and joint programme schemes. This should be of interest to those who teach acoustics and related subjects in higher education or students who intend to participate in an exchange programme to study abroad. The result from this study shows that the current acoustics degree programmes in China and in UK are generally compatible. However discrepancies in pedagogical approaches and the command of foreign language(s) mean that students will need to be prepared to quickly adapt to a different environment.
Telecom, Electroacoustics and Audio (TEA) education in two prestigious universities in Taiwan
Authors: Bai Mingsian R.
Published: April 2012

This presentation gives an overview of the acoustics education by the author's 21-year career in National Chiao-Tung University and National Tsing Hua University in Taiwan. Although it is generally recognized that acoustics is an “old” subject in classical physics, it finds many new applications in the modern world. The paradigm of acoustic education of the author is to gear the domain knowledge of acoustics to the needs of main-stream industries in Taiwan, including Computer, Community, Consumer electronics and Car, the so-called 4C industries, with emphasis placed upon telecom acoustics, eletroacoustics and audio signal processing (TEA) involved in the 4C products. To meet the ever changing challenges, a multidisciplinary approach including signal processing and control system is exploited, in addition to acoustics, in the pedagogic methodology. It is hoped that, with these new perspectives, classical acoustics can be rejuvenated within unified framework. In the author's career in education, more than 100 (including 30 in JASA) journal papers have been published, an institute of Sound and Music Innovative Technology (SMIT) and the Telecom acoustics, Eletroacoustics and Audio signal processing (TEA) laboratory have been launched in NCTU and NTHU, respectively, and a monograph on acoustic array systems is currently in preparation.
Acoustics at the Georgia Institute of Technology
Authors: Ryherd Erica E , Hastings Mardi C , Doane John
Published: April 2012

Acoustics at Georgia Tech spans multiple schools, including Mechanical Engineering, Electrical Engineering, Aerospace Engineering, Biomedical Engineering, Psychology, Music, Physics, Mathematics, and Architecture. The program began over 50 years ago and strengthened considerably in the 1960s and 1970s after Eugene Patronis, Ben Zinn, and Allan Pierce joined the faculty in the Schools of Physics, Aerospace Engineering, and Mechanical Engineering, respectively. Since then hundreds of students in acoustics have graduated and hold positions in academia and industry around the world. Currently the School of Mechanical Engineering has twelve academic and eight research faculty with primary interest in Acoustics and Dynamics. Areas of research include architectural acoustics, psychoacoustics, noise control, environmental acoustics, sustainable systems design, underwater acoustics, bioacoustics, ultrasonics, active/passive control, fluid-structure interaction, nonlinear acoustics, acousto-optics, micromachined sensors and actuators, vibration of nonlinear and frictional systems, shock and vibration isolation, structural acoustics, wave propagation, and structural health monitoring. Masters and Ph.D. level programs are offered in addition to various undergraduate courses. The depth of knowledge at Tech facilitates a variety of collaborations, allowing students a multi-disciplinary education in the science and application of acoustics. Student interactions are further facilitated by a number of organizations on campus, including a student chapter of the ASA.
Perceived elevation of simultaneously presented sound sources depends upon the correlation between the source signals
Authors: Martens William L. , Cabrera Densil A.
Published: April 2012

Speech stimuli were presented from pairs of loudspeakers placed at matched azimuth angles on either side of the listening position in an anechoic chamber. The elevation angles of the loudspeaker pairs was either 10 degrees below ear level, 10 degrees above ear level, or 30 degrees above ear level. An additional loudspeaker was placed directly above the listening position to serve as a reference for an elevation estimation task. As the correlation between simultaneously presented pairs of loudspeaker signals reproduced at a common elevation angle was decreased, the auditory source width increased to create a broad auditory image that spread out horizontally, but had a well defined apparent elevation angle. The elevation angles reported for these broad auditory images increased with an increase in the correlation between pairs of simultaneously presented speech sound sources. These results have implications for how to control most accurately the direction of multiple sources presented over 3-D arrays of loudspeakers, distributed vertically as well as horizontally.
Beamforming design for linear loudspeaker array with different feeding distribution
Authors: Zhang Baoying , Xie Xiang
Published: April 2012

In the recent years, loudspeaker array has been widely considered and used in household appliance products. For the flat-panel TV, how to use the ultra-thin loudspeaker array to generate a directional beam is becoming the current research focus. In this paper, the beamforming effects of linear loudspeaker array with different feeding distributions are compared. The simulation configures 7 loudspeakers in a line with a gap of 14cm. Its directional diagrams under 1KHz are examined with 5 types of feeding distributions, which include the uniform, binomial, triangular, inverted triangular and Dolph-Chebyshev distributions. The simulation shows that the linear loudspeaker array beamforming is significantly impacted by the feeding distributions and Dolph-Chebyshev distribution has the ideal performance in beamforming. which is because it makes a good compromise between the main lobe width and the side lobe height.
Acoustic radiation from the pipa and yueqin
Authors: Waltham Chris , Koster Evert , Kotlicki Andrzej , Simard James , Wolfe Nathan
Published: April 2012

The pipa and yueqin are Chinese plucked string instruments. The examples studied here have soundboards made of wu-t'ung (Paulownia) wood and each has a small cm-sized tone hole. The acoustic radiation patterns of these instruments have been measured as a function of angle and frequency. The measurements were made in an anechoic chamber and were obtained using an automated impact hammer. The radiation data are compared with measured vibration modes of the soundboxes. The spectra obtained peak at higher frequencies than are typical for Western instruments (500 Hz for the yueqin and 700 Hz for the pipa, compared to 100 Hz for the guitar), whose construction tends to emphasize the fundamental frequencies of the strings. The Helmholtz resonances of the pipa and yueqin have also been observed, but the effect of the tone holes have not been detected in the radiation data and their function is not understood.
Constrained beamforming for coherence sources parameters estimation
Authors: Tam Kai Chung , Lau Siu Kit , Tang Shiu Keung
Published: April 2012

The phased-microphone-array acquisition-system with beamforming signal processing provides sharp directivity in receiving sound source signal from desired direction. Conventional power beamforming algorithm makes use of spatial power spectrum to estimate the source locations and power by adjusting the stirring direction of the focusing beam. Although such power beamforming method shows success, there is still a research gap of power distortions caused by coherent sound fields. Furthermore the coherences between sources are still unable to identify, which could gives more detailed investigation of the source characteristics. We proposed a novel beamforming algorithm which is complex signal basis instead of signal power output basis in order to explore the phase information of the sources, moreover the coherence interference is eliminated by applying linear constrains which enhance the accuracy of the source-parameter estimation. The algorithm is further validated by numerical simulations with multiple coherence sources.
Sleep-disturbance and quality of sleep in Hong Kong in relation to night time noise exposure
Authors: van Kamp Irene , Lam K.C. , Brown A.L. , Wong T.W. , Law C.W.
Published: April 2012

Sleep disturbance is a main aversive effect of night time noise exposure; there is ample evidence that night time transport noise leads to acute effects such as physiological response, arousal, awakening, sleep stage changes, and amount of total sleep. Indirect effects as sleep disturbance, reduced performance and concentration have also been established. However, the long term effect of these changes is still unclear and highly hypothetical. As part of the Hong Kong transportation noise study, sleep quality was measured by means of two widely used instruments: a one question 11-point sleep disturbance scale and the Groninger Sleep Quality Scale (GSKS). Results show that 30% scores above 3 on the GSKS, indicating this be a matter of concern in Hong Kong, especially among residents of more exposed housing estates. However, this effect is not reflected in the percentage of highly sleep disturbed by road traffic noise. International comparison actually shows a lower curve in Hong Kong compared to elsewhere. Other noises were identified as sources of sleep disturbance in the survey. The influence of personal and contextual factors is highly comparable to those found elsewhere for annoyance, which includes noise sensitivity, access to a quiets side, density and overall residential satisfaction.
Vibration and noise induced sleep disturbance from freight trains – an experimental study
Authors: Smith Michael , Ögren Mikael , Persson Waye Kerstin
Published: April 2012

A substantial increase in transportation of goods on railway networks may be hindered by public fear of annoyance and sleep disturbance due to a corresponding increase in vibration and noise. As the majority of freight trains run during night time, sleep disturbance is expected to be the most serious adverse health effect arising from resulting vibration and noise. However, very little data exists that may be used to investigate the potential impact. As part of the European project Cargovibes, we are experimentally investigating sleep disturbance. An initial pilot study explored the relative perception of horizontal versus vertical vibration for subjects in a supine position and a following study investigated the relationship between various levels of horizontal vibration and sleep disturbance. Sleep was assessed using polysomonography and questionnaires. In total 12 subjects slept for six nights in the sleep laboratory, with one adaptation night, one control night and four nights with a variation of vibration exposures maintaining the same noise exposure. The results will be discussed at the conference.
Numerical simulations of oriented aggregation of sonochemically synthesized BaTiO3 nanocrystals
Authors: Yasui Kyuichi , Kato Kazumi
Published: April 2012

Numerical simulations of sonochemical production and aggregation of BaTiO3 nanocrystals have been performed under the experimental condition of Dang et al. [Jpn.J.Appl.Phys. 48, 09KC02 (2009)]. The theoretical model used in the simulations consists of three processes: chemical reactions, nucleation, and aggregation. The experimental data of the particle (aggregates) size distribution have been reproduced only when aggregation occur only for primary particles (nuclei). In the experiment of Dang et al., aggregates of sonochemically synthesized BaTiO3 nanocrystals were mesocrystals. For mesocrystals, the crystal axes of nanocrystals in an aggregate are aligned. In order to study the mechanism of mesocrystal formation, electric dipole-dipole interaction model has been studied in the present numerical simulations of collisions between two particles. It has been shown that primary particles aggregate with other particles and that the crystal axes are aligned by the dipole-dipole interaction. On the other hand, large aggregates do not aggregate due to the repulsive double-layer interaction which is stronger for larger particles. The results are consistent with the above simulations on the particle size distribution. It suggests that sonochemically synthesized 5 nm BaTiO3 nanocrystal may have spontaneous polarization.
A computational model for the dynamic aspects of primitive auditory scene analysis
Authors: Kashino Makio , Adachi Eisuke , Hirose Haruto
Published: April 2012

Recent psychophysical and neuroscientific studies suggest that auditory scene analysis is not fully determined by the spectrotemporal properties of acoustic signals, but also dependent critically on the various forms of predictions generated in the listener's brain. The predictions could be based on prior knowledge about the statistical properties of acoustic events in the real world, and regularity found in a given acoustic signal. Here, a computational model of primitive auditory scene analysis is proposed, with an emphasis on the dynamic interaction between the analysis of acoustic features and the generation of predictions. The model consists of several functional components, including: (1) the decomposition of spectrotemporal patterns into basic elements and their temporal changes, based on repetitive co-occurrence of spectral components, (2) the Bayesian inference incorporating prior knowledge and signal regularity, and (3) temporal gating using internally-generated signals. It will be examined whether the proposed model can explain the dynamic aspects of primitive auditory scene analysis, including the temporal buildup of stream segregation, multistable perception for prolonged stimulation, and the detection of repeated patterns embedded in random patterns.
Dynamic behaviour and active sound radiation control of a two-stage vibration isolation system equipped on a flexible plate
Authors: Sun Yao , Yang Tiejun , Dai Lu , Du Jingtao
Published: April 2012

This paper presents a general model of a two-stage vibration isolation system involving a flexible base plate with arbitrary boundary conditions. The dynamic behavior of the coupling system was obtained by using an impedance method in which the impedance matrix of the base plate was derived from a combined use of an improved Fourier series expansion and the Rayleigh-Ritz method. Subsequently, with the purpose of attenuation of sound radiation from the base plate structure, the optimal force information is formulated under various active control strategies including: 1) minimizing the total vibratory power of the coupled structure, 2) minimizing the sound power radiation from the base plate, 3) minimizing the vibratory power transmitted to the base plate, and 4) minimizing the mean square velocities at the isolator locations on the flexible plate. Numerical results were presented and discussed in detail. Finally, some concluding remarks are made.
Phonetic category formation in Korean-English bilingual children
Authors: Lee Sue Ann , Iverson Gregory
Published: April 2012

This is an NICHD (RHD061527A) funded study examining vowels and stops produced by Korean-English bilingual (KEB) children at 3, 5, and 7 years of age in order to determine whether bilingual children develop single or separate linguistic systems in the learning of their two languages. Though a long-standing theoretical issue in bilingualism, the question of whether bilingual children develop one or two distinct PHONETIC systems has not been fully explored. In the present study, 55 KEB children participated who first learned Korean, then English, in the US. Word-initial VOT and f0 values in the following vowel were measured for stops in both languages, as well as F1 and F2 values for vowels. We found developmental patterns and multi-dimensional representation of phonetic categories between vowels and stops. Specifically, 3 year-old KEB children did not distinguish between English and Korean vowels or stops, whereas 5 year-olds distinguished vowels but not the stop categories of Korean and English, and 7 year-olds distinguished both vowels and stops. Results suggest that the phonetic systems of bilingual children continue to evolve during the developmental process, and that bilingual children require different durations of exposure per speech category in order to establish detailed phonetic categories across languages.
Multi-band speech recognition using band-dependent confidence measures of blind source separation
Authors: Ando Atsushi , Ohashi Hiromasa , Hara Sunao , Kitaoka Norihide , Takeda Kazuya
Published: April 2012

One of the main applications of Blind Source Separation (BSS) is to improve performance of Automatic Speech Recognition (ASR) systems. However, conventional BSS algorithm has been applied only to speech signals as a pre-processing approach. In this paper, a closely coupled framework between FDICA-based BSS algorithm and speech recognition system is proposed. In the source separation step, a confidence score of the separation accuracy for each frequency bin is first estimated. Subsequently, by employing multi-band speech recognition system, acoustic likelihood is calculated from the estimated BSS confidence scores and Mel-scale filter bank energy. Therefore, our proposed method can reduce ASR errors which caused by separation errors in BSS and permutation errors in ICA, as in the conventional approach. Experimental results showed that our proposed method improved word accuracy of ASR by approximately 10%.
Analysis of discrepancy between subjective and objective evaluation of noise-reduced speech
Authors: Mizumachi Mitsunori
Published: April 2012

Discrepancy between subjective and objective evaluation is one of the annoying issues in speech processing including speech enhancement. Subjective evaluation is ideal, although it is time-consuming with a lot of participants. Then, objective distortion measures have been designed as the substitutes for subjective listening tests. However, each distortion measure is optimized under very restricted condition for the specific application. Therefore, discrepancy between subjective and objective evaluation of noise-reduced speech is often caused in the real world. In this paper, the factor of the discrepancy is investigated in detail by comparing the subjective evaluation with the short-term objective evaluation. Almost all state-of-the-art distortion measures introduce the importance weight in the frequency region. On the other hand, this paper considers the temporal variation of speech distortion to understand the relationship between subjective and objective evaluation of noise-reduced speech. Distribution of short-term speech distortion was prepared using the temporal frames with various lengths. It is found that the skewness of the short-term speech distortion distribution could be a clue for explaining the discrepancy between subjective and objective evaluation. [Work supported by NEDO, Japan]
Objective and subjective intelligibility evaluations of noise-reduction algorithms in Mandarin
Authors: Li Junfeng , Ying Dongwen , Fu Qiang , Yan Yonghong , Akagi Masato
Published: April 2012

In this paper, we summarize the recent work that we have done on the objective and subjective evaluations of single-channel noise-reduction algorithms in Mandarin Chinese. In the evaluations, clean Mandarin speech signals were first corrupted by three types of noises at two signal-to-noise ratios and then processed by five typical single-channel noise-reduction algorithms. The processed signals were presented to normal-hearing listeners for recognition in subjective evaluations, and passed to eight intelligibility prediction measures in objective evaluations. Subjective evaluation results showed that the majority of noise-reduction algorithms did not improve Mandarin speech intelligibility, and the objective evaluation results indicated that of all tested objective measures, the short-time objective intelligibility (STOI) measure provided the highest abilities in predicting Mandarin speech intelligibility in all conditions and in predicting the effect on speech intelligibility due to non-linear noise-reduction processing. These evaluation results reported here do provide valuable hints for analyzing and optimizing noise-reduction algorithms for Mandarin.
Differential OFDM for acoustic communications
Authors: Aval Yashar , Stojanovic Milica
Published: April 2012

High-rate acoustic communication typically rely on coherent detection which requires sophisticated channel estimation, and may in turn suffer a penalty in performance when channel tracking is less than ideal (a situation that is often inevitable on time-varying channels). To improve the robustness of signal detection, orthogonal frequency division multiplexing (OFDM) is considered with differentially coherent detection. The resulting receiver has very low computational requirements, and a potential to outperform coherent OFDM detection when channel tracking becomes difficult. Differential encoding is applied in the frequency domain (across carriers) so that it does not require the channel to remain constant over consecutive blocks in time. Instead, it requires only that the channel transfer function change slowly between adjacent carriers, but this requirement coincides with the basic premises of OFDM system design. At the same time, closely spaced carriers promote bandwidth-efficiency. For extreme situations, when close carrier separation leads to insufficient temporal coherence within each OFDM block, a method of partial FFT demodulation can be used with differentially coherent detection. The ensuing receiver algorithm is cast into the multi-channel (spatial diversity) framework, and its performance is illustrated using synthetic, as well as experimental data.
Robustness of acoustic interferometry for sediment geoacoustic characterization
Authors: Ren Qunyan , Hermand Jean-Pierre
Published: April 2012

Spectrogram of broadband sound field radiated by a moving ship usually exhibits striations in the frequency-range plane, whose structure is characterized by the multilayered waveguide properties. An acoustic interferometry technique was proposed for sediment geoacoustic characterization using local interference structure features. Such technique has been proven to be robust to source depth and range uncertainties by theoretical analysis and numerical simulation. In this paper, its robustness to receiver depth is discussed through real data processing, which is usually critical for inversion techniques based on matched field processing that exploiting the spatial and temporal structure of waterborne sound fields. Ship noise data were collected on the four elements of a drifting shallow receiver array in a soft sediment area, south of Elba Island in the Mediterranean Sea. For all the receivers, their inversion results together with uncertainties are in good agreement with that of active inversion method. The study demonstrates the reliability of the acoustic interferometry technique on even single-hydrophone receiver system for sediment geoacoustic characterization.
Acoustic enhancement in the Aylesbury theatre with the CARMEN® electroacoustic system
Authors: Rougier Christophe , Schmich Isabelle , Butcher Helen , Devallez Delphine
Published: April 2012

The 1200 seat Aylesbury Waterside Theatre opened in October 2010 in the UK. The theatre needed to be flexible enough to accommodate events and performances from pop to classical music, as well as opera and theatre. To host the different performances in the best acoustic conditions, it has been decided to design an acoustics adapted to amplified music (RT = 1,1s at mid frequencies) and to install an acoustic enhancement system in order to adapt it for other music events. The CARMEN® electroacoustic enhancement system, designed by CSTB, has been chosen and installed. This paper presents the design and results of the installation of the Carmen system in the Aylesbury Waterside theatre. It details the CARMEN® electroacoustic design and explains the tuning and fine-tuning session with musicians. Detailed explanations are given for the use with orchestral music. Measurement results and the subjective evaluation with the feedback of acousticians and musicians are finally presented.
Applications of large-scale finite element sound field analysis onto a music hall using ensemble averaged surface normal impedance
Authors: Otsuru Toru , Tomiku Reiji , Okamoto Noriko , Okuzono Takeshi , Asniawaty Kusno
Published: April 2012

To analyze the sound field in a practical room with complicated boundaries, the authors have developed large-scale finite element sound field analysis in both frequency and time domains. Although the surface normal impedance values of boundaries are required in the modeling process of the analysis, insufficient amount of the impedances are available to date. Then, to provide rather practical boundary conditions for numerical simulations on room acoustics, the authors have also proposed the concept and theoretical background of ensemble averaged surface normal impedance including the fundamental measurement technique. Herein, a brief summary of the finite element sound field analysis is given first. Next, the concept of the ensemble averaged surface normal impedance is explained. Then, several application analyses of a music hall's sound frequencies are conducted to show the resulting accuracy of the Large-scale finite element sound field analyisis.
Ultrasonic microbubbles: vehicles for molecular imaging and localized drug delivery
Authors: Zheng Hairong
Published: April 2012

Recent biomedical ultrasound development taking advantage of unique properties of ultrasound contrast microbubbles on ultrasonic molecular imaging, drug delivery and therapy has opened up powerful emerging applications. The intense radial oscillation of microbubbles makes them several thousand times more reflective than normal body tissues and emits significantly stronger acoustic signal. Besides, the oscillation resonance that microbubbles produce has several special properties that can be exploited to improve diagnoses and even for drug delivery and therapy. Moreover, selective ultrasound excitation can spatially-manipulate the microbubbles through the mechanism of acoustic radiation force and also destroy microbubbles to release the drug. In this talk, we present our current progresses on ultrasonic microbubbles as acoustic probes for molecular imaging, precise transportation micro-particles (drug), microbubbles and single cell to any specified loacation with MEMS technique by acoustic radiation force, as well as microbubble contrast agents as vehicles for ultrasound-mediated drug delivery in vitro and in vivo. The mechanism of the precise particle transportation using acoustic radiation force will also be discussed.
Optical characterization of inidividual liposome-loaded microbubbles
Authors: Luan Ying , Faez Telli , Gelderblom Erik , Skachkov Ilya , Geers Bart , Lentacker Ine , van der Steen Antonius , Versluis Michel , de Jong Nico
Published: April 2012

Newly developed liposome-loaded (LPS) microbubbles [1] were characterized by comparing their oscillating response with standard phospholipid-shelled (BARE) microbubbles using the ultra-high speed imaging camera (Brandaris 128). 73 LPS bubbles and 41 BARE bubbles of diameters ranging from 3 μm to 10 μm were insonified by narrow band pulses with a driving frequency ranging from 0.5 MHz to 4 MHz and an acoustic pressure from 5 kPa to 100 kPa. Shell elasticity of LPS bubbles (0.17±0.1 N/m) was nearly the same as that of BARE bubbles (0.19±0.1 N/m) for all investigated bubble sizes. Clear difference of shell viscosity was found for bubbles larger than 6 μm. Averaged viscosity of LPS bubbles (2.5×10-8 kg/s) was almost twice of that of BARE bubbles (1.4×10-8 kg/s). A second finding for LPS bubbles was the dominant “expansion-only” behavior (70% of LPS bubbles), while this was only 13% for BARE bubbles. Results from this study will facilitate future preclinical studies and clinical applications of LPS bubbles for ultrasound triggered drug delivery system. Reference 1. Geers, B., et al., J Control Release, 2011. 152(2): p. 249-56.
Combination of magnetic resonance-guided focused ultrasound and polymer-modified thermosensitive liposomes for cancer therapy
Authors: Ta Terence , Park Eun-Joo , MacDannold Nathan , Porter Tyrone
Published: April 2012

In this study, the response of solid tumors implanted in rat hindlimbs to doxorubicin (DOX) released locally from a novel polymer-modified thermosensitive liposome (pTSL) was investigated. The pTSL was engineered to release encapsulated DOX at lower thermal doses than traditional thermosensitive liposomes. Rat mammary adenocarcinoma cells were implanted in the hindlimb of healthy rats and allowed to grow to at least 100 mm3. DOX-loaded pTSL were injected intravenously and allowed to accumulate in the tumor interstitium over several hours. MR-guided 1.7-MHz focused ultrasound (MRgFUS) was used to heat the tumor volume and trigger the release of encapsulated DOX. Acoustic parameters (i.e. acoustic power, pulse duration, etc.) were identified to heat and maintain tumors at 40°C or 43°C for five minutes. Treatment with DOX-loaded pTSL and MRgFUS-mediated heating significantly reduced the rate of tumor growth. The response of tumors to DOX released from pTSL at 43°C was comparable to the response of tumors treated with unencapsulated DOX. The results of this study demonstrate that solid tumors can be treated successfully with DOX-loaded thermosensitive liposomes and MRgFUS with negligible toxic effects.
Unique gel-coupled acoustic physiological transducer for health and performance monitoring
Authors: Scanlon Michael
Published: April 2012

The U.S. Army Research Laboratory developed a unique gel-coupled acoustic physiological monitoring transducer that exploits acoustic impedance matching between the sensor and the skin. This optimizes the transmission of body sounds into the sensor pad, yet significantly rejects ambient airborne noises due to an impedance mismatch. Experiments have shown significant ambient noise reduction in a high-noise anechoic chamber test. The sensor's sensitivity and bandwidth produce excellent signatures for detection and spectral analysis of diverse physiological events such as heartbeats, breaths, wheezes, coughs, blood pressure, activity, and voice for communication. The health and performance of soldiers, firefighters, and other first responders in strenuous and hazardous environments can be continuously and remotely monitored with body-worn acoustic sensors. Comfortable acoustic sensors can be built into a helmet suspension or personal protective gear, or in a strap around the neck, chest, and wrist. Pulse wave velocity (PWV) transit-time between neck and wrist acoustic sensors can indicate systolic blood pressure on a beat-by-beat basis. Larger torso-sized arrays can be used to acoustically inspect the lungs and heart, or built into beds for sleep monitoring. Acoustics is an excellent input for sensor fusion, and combining acoustics with electrical-potential sensors such as electrocardiograms and electroencephalograms can produce interesting results.
Ultra low power low noise amplifier circuit design for electrically evoked compound action potential measurement of cochlear implant
Authors: Hong Feng , Li Ping , Xiao Ling
Published: April 2012

Cochlea implant is composed of sound processor and implant that can provide a sense of sound to people who are deaf or deeply hearing-impaired. Electrically Evoked Compound Action Potential (ECAP) Measurement, which is an effective way of monitoring the status of the auditory nerve, plays a vital role in the usage of cochlear implant. Design of an ultra low power low noise amplifier circuit for ECAP measurement based on Commercial Off The Shelf (COTS) is described and some experimental results of ECAP from guinea pigs are also presented. The circuit is flexible and transplantable that can be widely used in other medical implant devices.
Effects of in-phase and anti-phase head rotation of a remote avatar robot on median plane localization
Authors: Suzuki Yôiti , Ikeda Yoshitaka , Otani Makoto , Iwaya Yukio
Published: April 2012

Dynamic cues induced by a listener's movement markedly improve sound localization (e.g. Kawaura, 1991; Iwaya, 2003). Using a simplified version of an avatar robot called TeleHead (Toshima, 2004), this study investigated effects of horizontal head rotation on median plane localization. The head of our robot can rotate horizontally, synchronously following a listener's head rotation. Sound signals at the robot's two ears in an anechoic room are captured and reproduced for a listener in a remote soundproof room. The robot rotation was controlled to have in-phase or anti-phase rotation with the listener's head rotation with a ratio between the rotation magnitudes of a listener and the robot of 0.05, 0.1, or 1.0. Results show that the anti-phase dynamic cue increases front-back confusion when the ratio is 1.0, but the localization was little affected when it was 0.05 or 0.1. In contrast, the in-phase dynamic cue suppresses front–back confusion significantly, irrespective of the rotation magnitude. Consequently, the sound localization accuracy can be improved considerably if the robot head's direction of rotation in a remote site and that of a listener are identical, even if the robot head rotation magnitude is as little as 5 % of the listener's. (Work supported by MEXT, Japan)
A perceptual analysis of off-center sound degradation in surround-sound reproduction based on geometrical properties
Authors: Peters Nils , McAdams Stephen
Published: April 2012

Surround-sound reproduction is usually limited to a position where the listener maintains optimal perception of the reproduced soundfield. To improve the reproduction quality at off-center listening positions (OCPs), a better understanding of the nature of the perceived artifacts is necessary. Based on the geometrical relationships of a listener to the loudspeaker in a surround setup, an OCP can be characterized with three attributes: time-of-arrival differences, sound-pressure-level differences between the signal feeds, and the direction of the arriving wavefronts. Two listening experiments were conducted to elicit the perceptual effects of the off-center sound degradation of each of these three attributes in qualitative and quantitative terms. The five most often qualitatively described artifacts are related to the position of sound sources; their distance and depth; reverberation and envelopment; their spread and width; and sound coloration. The quantitative study found that off-center sound degradation is primarily caused by the level differences of the loudspeaker feeds. The time-of-arrival differences have a stronger perceptual effect on percussive sound material than on sustained sound material. In two out of three musical excerpts, off-center sound degradation was primarily correlated with artifacts related to the reproduction quality of reverb and envelopment.
Detection of noise sources in monitoring systems
Authors: Wierzbicki J. , Batko W.
Published: April 2012

One of the most important issue during continuous long-term environmental measurements in open space is connected with automatic identification of noise sources. It is particularly important in monitoring systems which collect data for creation and verification of noise maps where noise from road, rail and air traffic and from industry is taken into consideration. The determination of sound wave direction in observation point as a data pre-selection can be a first step in automation of noise sources identification process. In many cases due to permanent localization of roads and industrial plants such pre-selection should be sufficient. The idea of spatial sound monitoring system based on 3D microphone with procedures of data acquisition, processing and visualization and first results of noise sources detection are presented.
Near-field acoustic holography of cyclostationary sound fields
Authors: Chen Zhimin , Chen Hongchun , Zhu Haichao
Published: April 2012

The radiated sound field of rotating machinery or reciprocating machinery has a significant periodically time-variant nature. This is a kind of non-stationary sound field and called cyclostationary sound field. In the conventional planar near-field acoustic holography(PNAH), this kind of sound field is treated as stationary field, so the information relating to the change of frequency with time will be loss inevitably. In this article, the cyclic spectral density(CSD) instead of the complex sound pressure was adopted as reconstructing physical quantity in the PNAH, and the cyclostationary PNAH(CPNAH) technique was proposed. Meanwhile, focusing on the calculation complex of CSD and the accuracy of the cyclic nature extracted, the gathering slice method of CSD was proposed by referring time aliasing methods on time series. The experiment results illustrate that the cyclic nature of cyclostationary sound field may be extracted directly and the location of the source determined exactly as well.
Measuring the exposure to sound samples in subjective experiments
Authors: Yan Liang , Chen Kean , Gomez Florian , Stoop Ruedi
Published: April 2012

Traditional measures of environmental noise exposure concentrate on time and power (e.g. Ldn). For short measurements, time is, however, of secondary importance and the approach may come up with misleading results. In this paper, we propose a novel method based on short-term dose values evaluated along the playing time of the sound samples, to solve this problem. A comprehensive study on potentially influencing factors is carried out, discussing the partitioning method for short-term period analysis, the statistical treatment of the short-term dose values and four different frequency weightings. Eleven indices are then used to measure the exposure of the fixed duration sound sample. This lays the groundwork for the dose-annoyance relationship via subjective experiments.
Study and research of noise in some industrial factory
Authors: Zhu Yidan
Published: April 2012

Hearing loss is an occupational problem happened frequently in industrial factory. In the article, we investigate an industrial factory for several months, including the habit of worker and current noise situation of the environment. The conclusion shows some working area is exposed to high level noise, which is necessary to execute both noise reduction and hearing protection. And the whole region should be separated into different colors to warn the worker of different noise level.
Railway tunnel portal noise
Authors: HO Wilson , Wong Banting , Wong Wylog , Pang Alson
Published: April 2012

Railway tunnel portal noise is a concern in environmental impact assessment for railway projects. Railway noise is amplified inside the tunnel due to multiple reflections of highly sound reflective tunnel walls and such noise is then radiated from the tunnel portal. Noise Sensitive Receivers (NSRs) which are situated in close proximity of railway tunnel portal are adversely affected by the portal noise radiation in additional to the ordinary railway noise. Standard railway noise calculation procedures (Calculation of Railway Noise by Dept of Transport in UK, Transit Noise and Vibration Impact Assessment by Federal Transit Administration in USA, etc.), however, do not include a correction for such portal noise effect. This paper presents the experimental results of railway tunnel portal noise collected from Tai Po Kau tunnel on the East Rail Line in Hong Kong and proposes appropriate the tunnel portal noise corrections.
Use of floating slab track to control noise from rail transportation systems
Authors: Wilson George Paul
Published: April 2012

One of the most effective provisions for control and reduction of wayside noise and vibration from rail transportation systems is floating slab track. A floating slab track support is effective in reducing ground-borne noise and vibration from subway and surface track installations and can be very effective in reducing airborne noise radiated from viaduct and bridge structures. This presentation includes an outline of the development of the design parameters and materials used for the small vertical dimension, relatively light weight and low cost floating slab track support configurations as first installed in the early 1970's. This design concept has been further developed and improved as experience was gained with the early installations and there are now a large number of successful installations in service. There have been numerous developments of variations in the design parameters to accommodate the specific conditions unique to each application regarding geology and nearby occupancies. The development of the design parameters and limitations are presented and example designs are described along with measured noise control effectiveness results.
Investigation on shapes of the resonator related to external acoustic field in an open traveling-wave thermoacoustic generator
Authors: Xie Xiujuan , Yang Shaoqi , Zhou Lihua , Li Qing
Published: April 2012

Based on thermoacoustic effect, an open traveling-wave thermoacoustic generator could realize conversion between heat power and acoustic power, and then radiate sound into air space. The generator consisted of a loop tube and an open resonator. The shapes of resonator had tremendous effect on the external acoustic field radiated from the thermoacoustic generator. Uniform structure function was derived for different shapes of resonator. Acoustic wave equation taking the incident and reflected wave into account was established to acquire impedance distribution along the resonator. Based on the assumption of the point source, the external acoustic filed far away from the system was obtained. A model between uniform structure function of resonator and the external acoustic field was obtained due to the impedance matching around the open end. The external acoustic field 0~1m far away from the system was measured experimentally, which verified the applicability of the model. Therefore, the optimal structural coefficient related to the highest SPL 1m far away from the open end was acquired.
Auditory scene analysis: a competition between auditory proto-objects?
Authors: Denham Susan
Published: April 2012

Many sound sources can only be recognised from the pattern of sounds they emit, and not from the individual sound events that make up their emission sequences. We propose a new model of auditory scene analysis, at the core of which is a process that seeks to discover predictable patterns in the ongoing sound sequence. Representations of predictable fragments are created on the fly, and are maintained, strengthened or weakened on the basis of their predictive success. Auditory perceptual organisation emerges from the competition between these representations (auditory proto-objects). Rather than positing a global interaction between all currently active proto-objects, competition is local and occurs between proto-objects that predict the same event at the same time. The model has been evaluated using the auditory streaming paradigm, and provides an intuitive account for many important phenomena including the emergence of, and switching between, alternative organisations, the influence of stimulus parameters on perceptual dominance, switching rate and perceptual phase durations, and the build-up of auditory streaming.