bluuebunny/crossref_metadata_2025 huggingface dataset:
Uncertainty quantification and sensitivity analysis of transmission loss in the sea area northeast of Taiwan
Authors: Chang Yuan-Ying , Chen Chi-Fang , Chiu Yung-Sheng , Wei Ruey-Chang
Published: April 2012

Uncertainty of transmission loss, resulted from the uncertainty of geophysical and physical oceanographic parameters (features), could consequently contribute to the uncertainty of sonar performance prediction. This research adopts coupled ocean-acoustic modeling and compares with data of field observations over the continental shelf and slope close to North Men-Hua Canyon offshore northeastern Taiwan in order to study the uncertainty of transmission loss. This area contains range-varying sediment type, rapid-changing bathymetry, and complex water column activities brought by the Kuroshio intrusion, which jointly induce a highly uncertain environment for sound propagation. Mid- frequency sound propagation in this area is observed and modeled to interpret the propagation effect of the water column and seabed. Finally, the uncertainty of ocean model output and transmission loss in this area is quantified and the sensitivity is analyzed. The spatial and temporal effects on the ocean and acoustic field are also quantified in this study. [This research is sponsored by national science council. Project number: NSC 98-2623-E-002-013-D]
A binaural model for predicting speech intelligibility in rooms using noise and reverberation suppression processes
Authors: Li Vanessa , Xiang Ning , Braasch Jonas
Published: April 2012

Conventional metrics for predicting speech intelligibility are commonly described using the speech intelligibility index (SII) and speech transmission index (STI)--both of which are calculated using a monophonic signal. Under binaural conditions, these predictors often underestimate intelligibility due to the fact that beneficial binaural cues for unmasking detrimental effects are not accounted for. Beutelmann et al. [J. Acoust. Soc. Am. 127, 2479-2497 (2010)] proposed a binaural speech intelligibility model that determines the SII after suppressing spatially-separate noise using the equalization-cancellation (EC) process. This research expands on previous work by extending the model to analyze auditory scenes with more complex room acoustics, namely reverberation. In order to account for speech intelligibility degradation in the presence of room effects, the SII calculation is replaced by the STI. The current work also incorporates binaural release from reverberation by introducing an additional reverberation suppression mechanism into the model based on interaural coherence. The use of speech intelligibility metrics as an objective form of measurement may be used as a means to further understand binaural suppression processes within various room acoustic configurations through subjective listening tests.
Revisions to the EN12354 prediction method of calculating the flanking sound reduction index of lightweight building elements
Authors: Mahn Jeffrey , Pearse John
Published: April 2012

There is great interest worldwide in applying the standard, EN12354 to predict the flanking sound reduction index to lightweight building elements. However, there are several problems which must be overcome before the prediction method can be accurately applied to lightweight building elements. One problem is the prediction of the resonant component of the sound reduction index of the elements under investigation. As part of the work of COST Action FP0702, several methods of calculating the resonant component have been proposed and evaluated. The evaluation was conducted by comparing the predicted flanking sound reduction indices which were calculated using the different methods of calculating the resonant sound reduction index to measured values for a series of elements. The elements included single, homogeneous elements and double leaf elements. This paper presents the details of that evaluation. A correction factor based on the radiation efficiencies of the elements which was proposed by CSTB is recommended.
Effect of floating floor and raised floor on floor impact sound insulation of wooden construction
Authors: Hiramitsu Atsuo
Published: April 2012

The Act on the Promotion Wood for Public building was enforced in October, 2010 in Japan. According to this act, a public building in a low layer assumes a wooden construction as a rule or positively uses wood. Moreover, it is expected that the building such as apartment houses comes to be made from wooden. However, the floor impact sound insulation performance of the wooden constructions is low compared with that of the concrete constructions. This paper presents the effect of floating floor (dry double system floor) and raised floor (free access floor) on floor impact sound insulation performance in wooden construction. A reference floor constructed with the wood-frame construction was installed in the floor opening of the reverberation chamber, and the floating floors or the raised floor were built on it. Then, the reductions of transmitted floor impact sound level of them were measured. The results showed that the density of the surface material influences the floor impact sound interception performance in the case of the floating floor. In addition, the reductions of transmitted floor impact sound level in wooden construction were compared with them in concrete construction in the case of the raised floor.
Noise reduction of a double-skin façade considering opening for natural ventilation
Authors: Migneron Jean-Philippe , Potvin André
Published: April 2012

The growing interest in natural or hybrid ventilation systems brings a challenge for good integration of openings in building façades. With a noisy environment, there is an important limitation for the use of direct openings in common building envelopes. As a part of a research project dedicated to this problem, it is possible to evaluate the impact of several double-skin configurations, modifying openings, space between façades or the choice of construction assemblies. Experimental measurements made in laboratory conditions lead to the estimation of usual noise reduction and sound transmission class. Moreover, the airflow at constant differential pressure was assessed as functions of the aperture and compared to sound insulation. Analyzing those parameters together give useful information for the design of passive ventilation with a significant airflow when acoustical performance is an important issue.
The effect of receiving room sound field on the impact ball sound pressure level
Authors: Jeong Ho Jeong
Published: April 2012

Field measurement method of heavy-weight impact sound pressure level using impact ball have been used in Korea, Japan and Canada. Also this field measurement method is discussing in ISO. Impact force and subjective responses of impact ball are very similar with child's jumping and running. In Korea and Japan is considering that using impact ball as standard impact source instead of bang machine. It is reported that heavy-weight impact sound pressure level using bang machine was varied by the sound field condition of receiving room such as sound absorption power and room volume. In this study, it is checked that impact ball sound pressure level also affected by the receiving sound field condition. Impact ball sound pressure level was measured vertically connected reverberation chamber and sound absorption power was changed by polyester sound absorption blanket with air space and glass wool. The reverberation time at 1 kHz band was changed from 10 s to 0.2 s by sound absorption material. Impact ball sound pressure level measured without sound absorption material was 58 dB in Li, Fmax, AW, but the level was 46 dB with sound absorption treatment. From this result, it is confirmed that sound field correction term may be needed in the heavy-weight impact sound pressure level measurement method using impact ball.
Metamaterials for transformation acoustics applications
Authors: Cummer Steven , Popa Bogdan
Published: April 2012

Transformation acoustics is a paradigm for the creation of sound-manipulating materials and devices that are either difficult or impossible to derive through other theoretical approaches. It is based on the idea of a coordinate transformation of an arbitrary initial sound field. If the device you imagine can be defined in terms of a coordinate transformation, by squeezing, stretching, or displacing the sound field in a finite region, then transformation acoustics provides the mathematics for deriving the properties of a material in that same finite region that will have exactly the same effect on the sound field as the coordinate transformation. Transformation acoustics theory has lead to interest in designing acoustic composites, also known as metamaterials, that can to achieve the large range of material parameters needed for transformation acoustics designs. This presentation will describe recent efforts to design and fabricate composite materials with the acoustic properties needed to realize transformation acoustics devices, and also demonstrate their performance in experimental measurements.
Achieving a broadband plasmonic-type acoustic cloak using multilayered, spherically isotropic elastic shells
Authors: Guild Matthew , Haberman Michael , Alù Andrea
Published: April 2012

Previous work [Guild, Alù and Haberman, Wave Motion 48, 468-482 (2011)] has shown promising results for the cloaking of a sphere using non-resonant scattering cancellation. Originally developed for electromagnetic waves using plasmonic materials, this plasmonic cloaking technique differs from transformation-based cloaking, canceling the scattered field within the surrounding medium while allowing the incident wave to interact with the object. In contrast to a transformation-based cloak, construction of a plasmonic-type acoustic cloak can be achieved using ordinary fluid and isotropic elastic shells. Although such designs have been shown to be extremely effective, the bandwidth is fundamentally limited in this configuration due to the flexural shell resonances occurring within the isotropic elastic layers. To mitigate these effects, spherically isotropic elastic layers can be utilized, which allow for independent control of the transverse (tangential) layer properties. In this paper, full-wave analytic expressions are developed for a multilayered plasmonic-type acoustic cloak, consisting of an arbitrary number of spherically isotropic elastic layers. Using these expressions, examples for materials of practical interest in acoustic applications will be presented and discussed.
The dispersion effects in acoustic cloak with multilayered homogeneous isotropic materials
Authors: Cai Li , Wen Jihong , Han Xiaoyun
Published: April 2012

In the last decade, the coordinate transformation theory that developed to design electromagnetic (EM) cloaks has been further extended to design acoustic cloaks, which promise potential applications such as sound transparency and insulation. The realization of acoustic cloaks depends on the metamaterials with anisotropic density and bulk modulus. It has been shown that alternating layers of homogeneous isotropic materials can be used to approximate the anisotropic metamaterials that acoustic cloak required. As a kind of complex material, the dispersion with frequency is important to the cloaking effect of it. In this work, we specifically examine the frequency response of the multilayer structured acoustic cloaks by the acoustic scattering theory. The acoustic scattering cross sections of the cloak constructed by multilayered metamaterials with different dispersion are presented and discussed. The relation between the cloaking effect and the dispersion are analyzed. And the results are confirmed by numerical simulations of the finite element method.
Environmental noise management in Korea
Authors: Park Sang Kyu , Park Jae Sik , yun Hyo Seok , Yoon Soung Cheol
Published: April 2012

More than 40% of Koreans are exposed to excessive noise levels which can lead to serious health effects, community annoyance and sleep disturbance. Government policy and management of the noise are necessary to solve these problems. In this paper, some projects carried out to mitigate the excessive noise levels under the support of the Ministry of Environment in Korea have been introduced. They include the projects such as making a long-term plan in the field of noise management, amendment of the existing legislation and noise measurement methods, establishment of noise map directive, construction of traffic noise monitoring system, and management of low frequency noise.
Computational analysis of Maqam music: from audio transcription to structural and stylistic analyses, everything is tightly intertwined
Authors: Lartillot Olivier
Published: April 2012

Automated transcription of audio recordings into musical scores is a very challenging problem. Robust technological solutions are so far limited to simple cases and specific conditions, such as the focus on specific tractable musical instruments. The traditional conception of transcription as the inference of a single layer of notes ignores one core characterization of music as a multi-layer encapsulation of events of various scales (notes, gestures, motifs, phrases, etc.), where higher-level structures contextually guide the progressive discovery of lower-level elements. Modeling the emergence of these multiple structural layers, although complicating the problem, is in our view the only way to obtain a robust automation of music transcription, which is modeled here in the form of a multi-layer and recursive auditory scene analysis. Additionally, culture, as the experience of previous similar types of music, plays another essential role in guiding the more ambiguous aspects of music understanding. A previously proposed modeling of the impact of culture in structural understanding, applied in particular to Arabic Maqam music, is generalized here to the study of the influence of such cultural knowledge on music analysis, and in particular on the lowest layers of note transcription.
Finite-difference time-domain simulation of sound propagation through turbulent atmosphere
Authors: Ehrhardt Loïc , Cheinet Sylvain , Juvé Daniel
Published: April 2012

Sound propagating outdoors is influenced by turbulent fluctuations of the atmosphere. Unfortunately, theories only exist in limited configurations and outdoor experimentation is difficult. Numerical simulation is a good alternative for fully understanding the physics in place. The Finite-Difference Time-Domain (FDTD) model has already proven to reproduce many aspects of linear acoustics. It remains to demonstrate that it catches the physics of turbulence-induced effects. This is the aim of this contribution. FDTD simulations of sound propagation through turbulent atmosphere are performed. The general behavior and the statistical characteristics of the sound field are evaluated and compared to available theories. In the limiting configurations of weak or strong (saturated) sound perturbations, the simulations are in excellent agreement with the tested theories. In the intermediate configurations, some theoretical results agree with the simulations, while others show notable discrepancies. For example, the FDTD results suggest that there is a significant correlation between phase and amplitude fluctuations. These findings generally suggest that FDTD is an appropriate modeling tool to investigate sound propagation through complex configurations of the atmospheric fluctuations.
Validation of 3D numerical simulation for acoustic pulse propagation in an urban environment
Authors: Mehra Ravish , Raghuvanshi Nikunj , Chandak Anish , Albert Don , Wilson Keith , Manocha Dinesh
Published: April 2012

Acoustic pulse propagation in an urban environment is a complicated phenomenon with various acoustic effects like scattering, diffraction and reverberation, produced due to the presence of buildings. This work models acoustic propagation in an urban environment using adaptive rectangular decomposition (ARD), a time domain numerical simulation technique for solving the acoustic wave equation. It subdivides a space into rectangular partitions and utilizes analytical solution of the wave equation inside each partition along with sixth order Perfectly Matched Layer boundary conditions. The theoretical predications of the simulation are validated with experimental measurements performed in an artificial village. The simulation captures the near-periodic reflections and reverberation effects produced at the line-of-sight positions. For non-line-of-sight positions, high-order scattering and diffraction effects are also accurately modeled. We perform a comparison with the 2D FDTD method proposed by Liu and Albert[2006]. Since ARD is a 3D simulation technique, it captures all possible wave propagation paths, including the rooftop paths that not handled by the previous method. The predicted acoustic responses produced by the simulation match well with the measured responses for most sensor locations. Disagreements between simulation and measurements are discussed as well. The ideal session for this work is “Computational Acoustics”.
Computation of wall pressure fluctuations and flow induced noise by large eddy simulation
Authors: Nan Zhang , Hong-cui Shen , Yu-kui Tian
Published: April 2012

In industrial practice, the cavity-type oscillation is undesirable from the perspective of inducement of structure vibration and fatigue, generation of noise and drastic increase in drag on the body. A numerical work for the prediction of wall pressure fluctuations and flow-induced noise of cavity is performed in the paper. Firstly, the wall pressure fluctuations of a plate are computed and compared with experimental results of Small Anechoic Flow Facility in CSSRC. The robustness of large eddy simulation (LES) in unsteady flow calculation is analyzed. Secondly, the calculations of wall pressure fluctuations of shuttle holes are accomplished. The power spectra of wall pressure fluctuations are analyzed. The numerical predictions are compared with measured data. Finally, the flow induced noises of three cavities are predicted through LES and FW-H acoustic analogy. The computed results including flow pattern in cavity, vorticity distribution and radiated sound spectrum are analyzed. The computed results are compared with experimental data of Large Circulation Channel in CSSRC, and the numerical prediction method is validated. It shows that the numerical prediction method in the paper is credible. Key words: wall pressure fluctuations; flow induced noise; Large eddy simulation; FW-H acoustic analogy; cavity
Evaluation of barrier performance by direct environmental noise simulation
Authors: Seid K. H. , Leung R. C. K. , Lam G. C. Y.
Published: April 2012

After a city has experienced rapid urbanization, it is usually left with many pollution problems (e.g. air, noise, etc.) that hinder its further sustainable growth. Worsen by the rapid increase in the demands of land transportation for high population mobility; the traffic noise inevitably becomes a serious environmental problem. In countermeasure to the traffic noise problem and to compromise between limited space and costing, noise barriers are commonly implemented to protect sensitive land uses from noise pollution by mean of stopping, deflecting or reducing the noise propagation. Although recent studies have shown that the use of two or more screens in the barrier profile can enhance the diffraction efficiency of plane barriers in noise reduction without increasing its height. However, ground reflections are seldom included in the analysis, which could be a critical factor in the practical point of view. In this paper, a numerical technique derived from the high-fidelity time-domain computational aeroacoustics is adapted to direct simulation of environmental noise with an illustration of noise propagation over barriers. The robustness and accuracy of the method for predicting noise propagation will be discussed.
Geographic information in noise and vibration management solutions
Authors: Manvell Douglas
Published: April 2012

Environmental noise and vibration management is important in enabling businesses such as construction sites, mines, airports, etc. to operate within legal limits. Increasingly, businesses understand the value of communicating impact with communities and other stakeholders. Management includes planning and control of noise and vibration levels around the site and informing stakeholders of actions to be taken. Planning is normally based around calculation software while control often must rely on monitoring. Now, real-time measured data can link with calculation models to provide automatically updated noise maps giving businesses quick feedback to help optimise their actions whilst ensuring compliance with limits. Geographic information is used in many aspects of environmental noise and vibration management solutions. Geographical data such as from AutoCAD, Geographical Information Systems (GIS) and aerial photographs are becoming more widespread and cheaper and new solutions are appearing on the market. Geo-referencing is also central for the interaction between measurements, noise calculations and sensitive receptors. This paper presents the use of geographic information in environmental noise and vibration management solutions including the use of web-based GIS services to help businesses manage their noise and vibration impact. Examples of the use of GIS solutions to directly engage with communities will be presented.
A comparison of surface interpolation methods for development of noise map using Geographic Information System
Authors: Park In Sun , Park Sang Kyu , Ham Jeong Hoon , Han Jae Min
Published: April 2012

Noise map has become an important tool for the assessment and reduction of noise in cities, and can be manufactured by using ArcView GIS which is a PC-based Geographic Information System (GIS) software by Environmental Systems Research Institute, Inc (ESRI). The interpolate surface function of the ArcView GIS creates an output grid wherein each cell contains an interpolated noise value based on known noise values. In this study, several algorithms for surface interpolation, such as spline, inverse distance weighted, Kriging methods, are employed to compared the accuracy of noise levels in the downtown of a city.
Cavitation in confined spaces
Authors: Ohl Claus-Dieter , Xiong Sha , Gonzales Avila S. Roberto , Klaseboer Evert , Liu Ai Qun , Tandiono Tandiono , Ando Keita
Published: April 2012

Cavitation phenomena in real world are typically confined by one or more boundaries. Confining cavitation in small channels allows to study their interaction with cells, the formation of emulsions, and even sonochemical reactions in far greater detail as it would be possible in the bulk. However, it was expected that boundary layers will hinder bubble collapse more and more as the structure sizes are reduced. In this presentation the channel size is reduced even further, thus from microfluidic to nanofluidic channels. In microfluidic channels cavitation bubbles are generated with focused laser pulses and with acoustic waves. Acoustic cavitation in micrometer sized allows the formation of homogeneous emulsions, rapid rupture of cells (yeats and bacterias), and the dispersion of nanoparticles. While laser induced cavitation bubbles allow the study of bubble dynamics and bubble interaction in nanofluidic channels. In particular we will present experimental results on the dynamics of single bubbles and bubble-bubble interaction in nanochannels.
Possible implications of interaural mismatch in the place-of-stimulation on spatial release from masking in cochlear implant listeners
Authors: Kan Alan , Stoelb Corey , Goupell Matthew , Litovsky Ruth
Published: April 2012

Recent research suggests that bilateral cochlear implant (CI) users have improved speech intelligibility in noisy environments compared to unilateral CI users. This may not be surprising given that in normal hearing (NH) listeners, binaural hearing allows them to localize sounds and this ability allows them to benefit from a spatial release from masking (SRM). However, SRM benefits are much less in CI users and vary amongst users. This may be due to the interaural mismatch in the place-of-stimulation across the ears in CI users and occurs due to differences in neural survival and electrode implantation depth across the ears, leading to different parts of the cochlea being excited by electrodes of the same number. Data will be presented that shows that with increasing interaural mismatch, CI users typically heard lateralized or multiple sounds. In some CI users, interaural mismatches greater than 3 mm leads to an inability to use binaural cues. These effects may impact a CI user's ability to obtain SRM. Preliminary results from a CI simulation study conducted to investigate the effect of interaural mismatch on SRM will also be presented. Work supported by NIH-NIDCD R01 DC003083
Experimental analysis on barrel zoom module of digital camera for noise source identification and noise reduction
Authors: Jeong Un-Chang , Yoon Ji-Hyun , Jeong Jae-Eun , Lee Jung-Youn , Oh Jae-Eung
Published: April 2012

Noise of digital camera has been noticeable to its users. Particularly, noise of a barrel assembly module in zoom in/zoom out operation is recorded while taking a video. Reduction of barrel noise becomes crucial but there are not many studies on noise of digital camera due to its short history of use. In this study, experiment-based analyses are implemented to identify sources of noise and vibration because of complexity and compactness of the barrel system. Output noise is acquired in various operation conditions using synchronization for spectral analysis. Noise sources of a barrel assembly in zoom operating are first identified by the comparison with gear frequency analysis and then correlation analysis between noise and vibration is applied to confirm the generation path of noise. Analysis on noise transfer characteristic of zoom module is also carried out in order to identify the most contributing components. One of possible countermeasures of noise in zoom operating is investigated by an experimental approach
Influential parameters in system damping performance of viscoelastically damped plates
Authors: Verstappen André , Pearse John
Published: April 2012

Vibration in metal panels is often undesirable as it can lead to high noise levels, reduced equipment lifetime and physical discomfort. For this reason, vibration and acoustic performance is an important aspect to consider during the design stage. Unconstrained viscoelastic coatings can provide a simple solution for damping vibrations of metal panels. It is well known that the damping performance of viscoelastic materials is dependant on the ambient temperature and frequency of excitation. It is also known that system damping performance is affected by plate boundary conditions, substrate material and the thickness ratio between the substrate and damping material. A fractional factorial experimental design was employed to determine the interactions of these variables and their relative influence on the system damping performance. Fully clamped and simply supported aluminium and steel plates of two sizes were examined. Temperatures and damping layer thickness ratios typical of normal use were used. Performance was measured by the system loss factor which was obtained using a sound intensity method [1]. 1. Lim, M. K., A sound intensity technique for determining structural damping of a panel exposed to noise. Applied Acoustics, 1991. 32(Copyright 1991, IEE): p. 311-19.
Dialectal alarm words recognition based on a hybrid model of Hidden Markov Models and the BP Neural Network
Authors: Lu Ling , Zeng Xiangyang , Cheng Xiaobin , Yan Zhaoli
Published: April 2012

This paper explores the small-vocabulary speaker-independent isolated-word speech recognition technology. A recognition system based on a hybrid model of Hidden Markov Model and BP Neural Network is constructed. The HMM is used for computing the Viterbi output score which is inputted into the BP network to acquire the classification information. A corpus with more than 2500 speech samples is created, which includes three dialects (mandarin, shannxi dialect, English), and each kind of dialect contains four alarm word (“help”, “hijack”, “murder”, fire”). Recognition experiments are carried out using the corpus. The results show that the hybrid model has higher performance than the hidden Markov model.
The North Pacific Acoustic Laboratory (NPAL) deep-water acoustic propagation experiments in the Philippine Sea
Authors: Worcester Peter F. , Andrew Rex K. , Baggeroer Arthur B. , Colosi John A. , D'Spain Gerald L. , Dzieciuch Matthew A. , Heaney Kevin D. , Howe Bruce M. , Kemp John N. , Mercer James A. , Stephen Ralph A. , Van Uffelen Lora J.
Published: April 2012

The North Pacific Acoustic Laboratory (NPAL) Group has performed a series of experiments to study deep-water acoustic propagation and ambient noise in the northern Philippine Sea: (i) 2009 NPAL Pilot Study/Engineering Test (PhilSea09), (ii) 2010–2011 NPAL Philippine Sea Experiment (PhilSea10), and (iii) Ocean Bottom Seismometer Augmentation of the 2010–2011 NPAL Philippine Sea Experiment (OBSAPS). The goals are to (i) understand the impacts of fronts, eddies, and internal tides on acoustic propagation in this oceanographically complex and dynamic region, (ii) determine whether acoustic methods, together with other measurements and ocean modeling, can yield estimates of the time-evolving ocean state useful for making improved acoustic predictions and for understanding the local ocean dynamics, (iii) improve our understanding of the physics of scattering by small-scale oceanographic variability, and (iv) characterize the depth dependence and temporal variability of the ambient noise field. In these experiments, moored and ship-suspended low-frequency acoustic sources transmitted to a newly developed Distributed Vertical Line Array (DVLA) receiver capable of spanning the water column in deep water. The acoustic transmissions and ambient noise were also recorded by the towed Five Octave Research Array (FORA), by acoustic Seagliders, and by ocean bottom seismometers during OBSAPS. [Work supported by ONR.]
Measured low frequency intensity fluctuations over a 107 km path in the 2009-2010 Philippine Sea experiment
Authors: White Andrew W. , Andrew Rex K. , Mercer James A. , Worcester Peter F. , Dzieciuch Matthew A.
Published: April 2012

A broadband low-frequency acoustics pilot study was conducted in the Philippine Sea in April/May of 2009. 19,071 M-sequences were transmitted over a period of 60 hours at a range of 107 km to a vertical array of hydrophones. Timeseries of acoustic intensity for arrivals corresponding to known paths are formed. Results from a simulation of acoustic propagation through a time-dependent internal wave perturbed sound speed field agree qualitatively with arrivals for two of the acoustic paths but not with the arrivals for the path which had a shallow upper turning point of ~60 m. Intensity fades of 5 to 10 dB which last for approximately 18 or 20 hours are observed in this shallow-turning path. Estimates from data of spectra and correlation times for acoustic intensity will be compared to Monte Carlo Parabolic Equation based predictions. [Funding provided by ONR]
The effects of roughness on transmission loss in regions with elastic bottoms
Authors: Isakson Marcia , Chotiros Nicholas
Published: April 2012

On rough elastic interfaces, incident acoustic waves couple more readily into the shear mode due to the steeper local angle relative to the nominal incident angle. This effect has a profound influence on transmission loss in shallow water areas with elastic bottoms. Although rock interfaces are often covered with sand or other sediment, the effect is still significant even for overlying sediment layers several acoustic wavelengths thick. In this study, the effects of roughness on transmission loss in an area with a hard elastic bottom with and without an overlying sediment layer are studied using a finite element transmission loss model. Results are compared with transmission loss data measured in an area with sediment layers over hard rock off the Western coast of Australia. [Work supported by ONR, Ocean Acoustics]
The acoustical design of Xiamen University Concert Hall
Authors: Zhao Yuezhe , Wu Shuoxian
Published: April 2012

Xiamen University is located in the Fujian Province, South East of China. Xiamen University Concert Hall is the essential musical education site for the college students, as well as for holding important meetings. The concert hall has 560 seats. It has a comparatively long reverberation time to offer a fullness and reverberant sound field for music performance. At the same time, rich early reflections from the ceiling and the side walls together with the enough signal to noise ratio guarantee speech intelligibility when using a loudspeaker system. With this conception in the acoustical design of the concert hall, the use of changeable absorptive components was avoided which may influence the brightness and liveness of the chamber music hall. After the completion of the building, acoustical measurements were taken and the measurement results are also given in this paper. Since autumn 2010 when the concert hall was finished, music performance and meeting events have been successfully held in the hall. It has become the main hall for the musical education and performance, as well as the meeting center for the college.
Investigation of improved metrics for the characterization of musicians' room acoustical conditions in concert halls
Authors: Ranjbari Behzad
Published: April 2012

A number of metrics for assessing the acoustical conditions for performers on concert hall stages have been proposed, notably by Anders Gade but also others. However, the subjective relevance of existing stage acoustic metrics for musicians, appears mainly to be associated with the communication with the audience rather than with the communication between musicians. No acoustic metrics have been identified to assess the balance between the hearing of others vs. the hearing of one's own instrument, which appears paramount to orchestral musicians. Problems regarding presence of orchestra, directional characteristics of instruments, distances from instruments to ears of musicians, etc., also have been an issue for researchers, making the work difficult, expensive and imprecise. However, in this paper, due to the comparative approach used, some of these problems were removed, since they are basically the result of properties of orchestral arrangement rather than stage conditions and can be assumed similar from one stage to another. In this paper, a number of laboratory experiments as well as measurements on real stages have been studied and a pair of metrics, namely GSelf and GOthers are suggested to assess the balance between the hearing of self and that of hearing others.
FM bats use transform-based biosonar imaging
Authors: Simmons James , Warnecke Michaela
Published: April 2012

Big brown bats (Eptesicus fuscus) perceive target range from echo delay using neuronal-delay lines that extract and display the time that elapses between successive occurrences of individual frequencies in each FM broadcast and its subsequent echoes. The bat's delay accuracy is very sharp for echoes containing all broadcast frequencies. Decreasing the bandwidth of echoes reduces the number of frequencies available for estimating delay, which degrades acuity. However, removal of frequencies triggers the operation of a second, parallel estimation process, loosely related to the cepstrum, whereby delay differences between two or three closely-spaced reflections are estimated from the pattern of modulations (peaks and notches) in the echo spectrum. When a wide span of frequencies is removed, as in lowpass filtering, multiple spectral-modulation solutions coexist, which the bat perceives as many different glints distributed across several hundred microseconds. This defocuses the bat's images for the echoes and renders them not capable of clutter masking. The effect of spectral blurring on delay images is opposite to that expected from time-domain blurring, as demonstrated in 3 different delay-discrimination experiments. [Work supported by ONR and NSF]
Overcompensation of echo attenuation and dual-component biosonar control in echolocation of an Atlantic bottlenose dolphin (Tursiops truncatus)
Authors: Li Songhai , Nachtigall Paul E. , Breese Marlee
Published: April 2012

Transmitting biosonar clicks and auditory evoked potential (AEP) responses triggered by the clicks were synchronously recorded during echolocation in an Atlantic bottlenose dolphin (Tursiops truncatus) trained to wear suction-cup EEG electrodes and to detect targets by echolocation. Three targets with target strengths of −34, −28 and −22 dB were used at a target distance of 2 to 6.5 m for each target. The results demonstrated that the AEP appeared to both transmitting echolocation clicks and echoes during echolocation, with AEP complexes consisting of alternative positive and negative waves. The echo-related AEP amplitudes were obviously lower than the transmitting click-related AEP amplitudes for all the targets at the investigated target distances. However, for targets with target strengths of −22 and −28 dB, the echo-related AEP response amplitudes increased at further target distances, demonstrating an overcompensation of echo attenuation with target distance in the echo-perception system of the dolphin biosonar. Measurement and analysis of transmitting click intensities showed that the click levels increased with target distance (R). The results demonstrated that a dual-component biosonar control system formed by intensity compensation behavior in both the transmission and receiving phases of a biosonar cycle exists synchronously in the dolphin biosonar system.
Adaptive echolocation behavior in a complex sonar scene
Authors: Moss Cynthia
Published: April 2012

Adaptive sonar behavior in bats provides a window to echo information processing and perception of complex scenes. Echolocating bats produce ultrasonic vocalizations and receive a cascade of echoes from a single sonar call when the environment contains multiple reflecting sources. Some echoes may return from food and others from obstacles, and the bat must rapidly sort and identify the sources of echo returns to analyze the sonar scene and accurately control its flight. Big brown bats produce frequency modulated sonar signals that change in direction, duration, bandwidth and repetition rate as they inspect objects at different directions and distances. The work presented here will focus on adaptive sonar behavior in bats as they track a selected prey item in the presence of other objects, both obstacles and other prey. Data suggest that echo stream segregation of targets in clutter is supported by finely tuned adaptive sonar signal control.
Detection on the presence and frequency use pattern of cetacean tonal sound
Authors: Lin Tzu-Hao , Chan Hsiang-Chih , Chen Chi-Fang , Akamatsu Tomonari , Chou Lien-Siang
Published: April 2012

Passive acoustic monitoring (PAM) had already been proved to assess the presence of many cetacean species successfully. However, the continuous recording makes the manual data analysis difficult. In the present study, an automatic detection algorithm was developed for tonal sounds produced by Indo-Pacific humpback dolphins. The algorithm included a tonal sound detector which found the local spectral peaks and sampled the dominant frequencies every 5.3 ms. A noise exclusion process was used to exclude the spectral peaks with wide -3 dB bandwidth. After filtering the isolated frequency points within specific duration and frequency range, the adopted frequencies of tonal sounds could be obtained. The result showed the algorithm had 70% correct detection and 2.8% false positive based on each 1 sec time bin in 10 field recordings. The first to third quartile of adopted frequencies showed significant difference with those extracted manually, but the differences were only 245-489 Hz in average. The current algorithm performed considerably faster than real time. In the future, it can be applied as a first step in a real-time monitoring.
A numerical study of the role of the noseleaf in the Egyptian slit-faced bat
Authors: Zhuang Qiao , Wang Xiaomin , Li Mingxuan
Published: April 2012

Around 300 bat species are known to emit their ultrasonic biosonar pulses through the nostrils. This nasal emission coincides with the presence of intricately shaped baffle structures surrounding the nostrils. Some prior experimental evidence indicates that these “noseleaves” have an effect on the shape of the animals' radiation patterns. Here, a numerical acoustical analysis of the noseleaf of a slit-faced bat species is presented to show that all three distinctive parts of its noseleaf (“pit”, “upper leaf”, “lower leaf”) have an effect on the acoustic near field as well as on the directivity pattern. In their effects on the near field, the noseleaf parts showed a tendency toward spatial partitioning with the effects due to each part dominating a certain region. However, interactions between the acoustic effects of the parts were also evident, most notably, a synergism between the frequency-dependent effects of two parts of the noseleaf (“pit”, “lower leaf”) to produce an even stronger frequency selectivity. supported by the Natural Science Foundation of China (Project No. 10974222), and the China Postdoctoral Science Foundation funded project (No. 20090450599). Bat specimen provided by the School of Physics, Shandong University, China.
Measurement of brain tissue motion using extended autocorrelation strain estimator
Authors: Ternifi Redouane , Elkateb Hachemi Amar Melouka , Remenieras Jean-pierre
Published: April 2012

Pulsatile motion of brain parenchyma results from cardiac and breathing cycles. In this study, transient motion of brain tissue was estimated using an Aixplorer\textregistered imaging system allowing an ultrafast 2D acquisition mode. The strain was computed directly from the ultrafast IQ complex data using the extended autocorrelation strain estimator (EASE), which provides great SNRs regardless of depth. The EASE first evaluates the autocorrelation function at each depth over a set of successive IQ pairs. This estimates the mean change in phase over time, which is proportional to the velocity. A second autocorrelation is evaluated on the results of the first autocorrelation. This estimates the mean change in phase over depth, which is proportional to the strain rate. The developed algorithm was first validated on “in vivo” data acquired at 7.5MHz from the carotid. Tissue velocity and strain rate were estimated on artery wall and adjacent regions. The estimated displacement velocity and displacement of the wall artery were 2.5 cm/s, and 150 μm respectively. The displacement velocity and displacement of the region near the surface were 1 cm/s and 30 μm respectively.
Influence of temperature field produced by phase aberration in HIFU
Authors: Liu Zhenbo , Fan Tingbo , Guo Xiasheng , Zhang Dong
Published: April 2012

High Intensity Focused Ultrasound (HIFU) is a noninvasive treatment in the field of cancer therapy. The principle of this technique is to raise the tissue temperature to relatively high values and cause thermal coagulation and ablation of cells by using tissue penetrable, strong directional and easily focused ultrasound. The phase aberration introduced by tissue inhomogeneity affects the tissue temperature evidently on the focus. This article studies the influence of temperature field debased by phase aberration theoretically using the 3D KZK (Khokhlov-Zabolotaskaya- Kuznetsov) combined phase aberration screen models and simulates the temperature field by solving Pennes equation. The peak and the size of the temperature with various phase aberration will be compare to homogeneity. In order to prove the theoretical results a series of in vitro experiments will be execute.
Paclitaxel-liposome loaded microbubbles for ultrasound-triggered drug delivery in vitro and in vivo
Authors: Yan Fei , Li Lu , Deng Zhiting , Jin Qiaofeng , Zheng Hairong
Published: April 2012

The aim of this work was to develop paclitaxel-liposome loaded microbubbles (PTX-loaded MBs) and to investigate the efficacy of chemotherapy through ultrasound-triggered drug delivery in vitro and in vivo. PTX-loaded liposomes were prepared by a minor modification of thin film hydration method and further conjugated to the surface of microbubbles through biotin-avidin linkage. The resulting payload-loaded MBs were characterized and applied to ultrasound assisted chemotherapy in breast cancer. Our results showed the MBs were able to achieve satisfactory drug encapsulation efficiency. Under ultrasound exposure, about 9.54-fold higher drug release and a significant improvement of cell uptake than that of loaded liposomes were observed. In addition, PTX-loaded MBs showed significantly greater tumor growth inhibition both in vitro and in vivo xenograft growth of breast tumor cells, compared with PTX-loaded liposomes and unloaded MBs. Drug distributions assay in various organs (heart, liver, spleen, lung, kidney and tumor) indicated about 3-fold higher PTX enriched in tumor. Histological examinations further demonstrated the tumor growth inhibition might contribute to increased apoptosis and reduced angiogenesis in tumor xenografts. In conclusion, the study indicated the PTX-loaded MBs significantly increased the anti-tumor efficacy and can be used as a potential chemotherapy approach for ultrasound assisted breast cancer treatment.
Application of dual frequency ultrasound method in through transmission measurements
Authors: Karjalainen Janne Petri , Pakula Michal , Grimal Quentin , Töyräs Juha , Jurvelin Jukka Sakari , Laugier Pascal
Published: April 2012

Soft tissue layers overlying bones, with unknown thickness, can produce significant errors to bone quantitative ultrasound measurements. In this study dual frequency ultrasound (DFUS) technique, developed originally for pulse-echo measurements, is applied and evaluated in a configuration typical to clinical through-transmission measurement. A mathematical algorithm is presented for determination of soft tissue composition, i.e. amount of lean and fat tissue, and correction of typical clinical parameters such as broadband ultrasound attenuation (BUA) and speed of sound (SOS). Ultrasound soft tissue phantoms mimicking lean and fat tissues, were tested in five different configurations by varying the composition (0-100% of fat). Different configurations were built using 10mm of fat or lean and 30mm of fat or lean, and total thickness of soft tissue constructs varied from 20mm to 40mm. Using through-transmission measurements at 0.5 MHz center frequency the thickness of soft tissue layers could be determined using DFUS technique (low and high frequency band 0.4-0.45 and 0.55-0.6 MHz, respectively). The average absolute error of fat/muscle layer thickness was 2.2mm (SD=1.3mm). The results suggest that DFUS technique may be used in through-transmission to assess the soft tissue content over/underlying the bone, and subsequently to reduce soft tissue induced errors in quantitative ultrasound measurements.