bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustical scattering from N spheres using a multilevel fast multipole method
Authors: Gumerov Nail A. , Duraiswami Ramani
Published: October 2013

We develop an efficient computational method for wave scattering from a large number of spherical objects that are characterized by their radii, locations, and complex acoustical impedances of the surfaces. The direct T-matrix method for solution of the problem that was developed and tested in [Gumerov and Duraiswami, J. Acoust. Soc. Am. 112, 2688–2701 (2002)] is inefficient for computations involving a large number of scatterers. Here, we implement and test a multilevel fast multipole method for speeding up the solution and achieving better memory complexity. The method is based on hierarchical space subdivision with oct-trees using optimal space-partitioning, on a theory for fast translation and re-expansion of multipole solutions of the Helmholtz equation, and employs an iterative technique for the solution of large dense systems of linear equations with reflection-based iterations. For N scatterers the method provides O(NlogN) asymptotic complexity opposed to O(N3) complexity of the direct T-matrix approach. The results of computations were tested against solutions obtained by other methods, such as the boundary element method and the direct T-matrix method tested in our early study, and show the computational efficiency and accuracy of the solution technique. [Work supported by NSF Awards 0086075 and 0219681 is gratefully acknowledged.]
The probability of young children understanding their teacher in everyday teaching situations
Authors: Bradley John S. , Sato Hiroshi
Published: October 2013

This paper examines the probability of grades 1, 3, and 6 students understanding their teacher in a normal teaching activity. The results of speech intelligibility tests in 34 enclosed classrooms were analyzed to relate childrens’ ability to understand speech to measured signal-to-noise ratios (as well as Speech Transmission Index and useful-to-detrimental sound ratios) for each age group. Measurements of speech and noise levels during a normal teaching activity were used to determine the distribution of signal-to-noise ratios in normal teaching situations. Combining these two sets of data shows that while 51% of the grade 6 students experienced near-to-ideal acoustical conditions only 9% of the grade 1 students had close-to-ideal conditions in these apparently good classrooms. Estimates of ideal goals for classroom signal-to-noise ratios for each age group will be presented. [Work supported by CLLRnet.]
Acoustic measurement of the behavioral response of Arctic riverine fish to seismic sound
Authors: Gyselman Eric , Jorgenson John
Published: October 2013

Renewed interest in oil and gas development in the Canadian Arctic has lead to proposals to conduct seismic surveys along the entire length of the Mackenzie River. However, little is known about the effects of seismic sound (air guns) on fish in riverine environments. In 2004, Fisheries and Oceans Canada carried out a study to look at the effects of seismic sound on the physiology and behavior of fish in the Mackenzie River. The behavioral component used a split-beam acoustic system to measure the response of fish to varying levels of seismic sound. Targets were tracked with SonarDatas Echoview Tracking Module. Two experiments were carried out. In the first, the acoustic launch was anchored over a concentration of fish while the seismic barge approached. This experiment simulated the conditions proposed for the actual seismic survey. During the second, the acoustic launch was allowed to drift over concentrations of fish. The seismic barge was stationary. When individual fish were seen in the acoustic beam, the air guns were fired. This experiment measured the overt fright response of fish to the seismic sound. Initial results from both studies indicate that fish show no direct behavioral response to the seismic sound.
Adverse effects of shock waves and strategies for improved treatment in shock wave lithotripsy
Authors: McAteer James A. , Evan Andrew P. , Connors Bret A. , Williams James C. , Willis Lynn R.
Published: October 2013

Lithotripter SWs rupture blood vessels in the kidney. This acute trauma, accompanied by a fall in renal function, can lead to significant long-term effects such as profound scarring of the kidney cortex and renal papillaea permanent loss of functional renal mass. SWL has been linked to new-onset hypertension in some patients, and recent studies suggest that multiple lithotripsies can actually alter a patient’s stone disease leading to formation of stones (brushite) that are harder to break. Cavitation and shear appear to play a role in stone breakage and tissue damage. Progress in understanding these mechanisms, and the renal response to SWs, has led to practical strategies to improve treatment. Slowing the SW-rate, or initiating treatment at low kV/power both improve stone breakage and reduce the number of potentially tissue-damaging SWs needed to achieve comminution. The observation that SWs cause transient vasoconstriction in the kidney has led to studies in pigs showing that a pre-conditioning dose of low-energy SWs significantly reduces trauma from subsequent high-energy SWs. Thus, SWs can induce adverse effects in the kidney, but what we have learned about the mechanisms of SW action suggests strategies that could make lithotripsy safer and more effective. [Work supported by NIH-DK43881, DK55674.]
Shock wave lithotripsy at 60 or 120 shocks per minute: A randomized, double-blinded trial
Authors: Pace Kenneth , Ghiculete Daniela , Harju Melanie , Honey R. John
Published: October 2013

Rate of shock wave administration is a factor in the per-shock efficiency of SWL. Decreasing shock wave frequency from 120 shocks per minute (s/m) may improve stone fragmentation. This study is the first to test this hypothesis in vivo. Patients with previously untreated radio-opaque kidney stones were randomized to SWL at 60 or 120 s/m and followed at 2 weeks and 3 months. Primary outcome was success rate, defined as stone-free or asymptomatic fragments 5 mm in size 3 months post-treatment. 111 patients were randomized to 60 s/m and 109 to 120 s/m. The groups were comparable on age, gender, BMI, stent status, and initial stone area. Success rate was higher for 60 s/m (75% versus 61%, p=0.027). Patients with stone area 100 mm2 experienced the greatest benefit: success rates were 71% for 60 s/m versus 32% (p=0.002), and stone-free rates were 60% versus 28% (p=0.015). Repeat SWL treatment was required in 32% treated at 120 s/m versus 18% (p=0.018). Fewer shocks were required (2423 versus 2906, p=0.001), but treatment time was longer (40.6 versus 24.2 minutes, p=0.001). SWL treatment at 60 s/m yields better outcomes than 120 s/m, particularly for stones 100 mm2.
Formant frequencies as indicators of body size in red deer roars
Authors: Reby David , McComb Karen , Darwin Chris , Fitch W. Tecumseh
Published: October 2013

Recent studies of animal vocal communication have emphasized the potential for vocal tract resonances to encode information on the size of callers and the need for receivers to attend to this information, in particular in the context of intra-sexual competition and inter-sexual mate choice. Our recent work on red deer roaring, a classical example of a sexual communication signal, is reviewed here. A combination of anatomical analyses of the vocal apparatus, acoustical analyses, and playback experiments using re-synthesized calls has enabled us to show that: (i) red deer and fallow deer males have a descended and mobile larynx, an anatomical innovation that was previously believed to be uniquely human and that enables callers to modulate their formants during vocalizing; (ii) minimum formant frequencies provide an honest indication of body size in red deer roars and (iii) stags use rivals’ minimum formant frequencies in assessment during male-male contests, and adjust the formants of their own replies in relation to what they hear.
The stabilized, wavelet-Mellin transform for analyzing the size and shape information of vocalized sounds
Authors: Irino Toshio , Patterson Roy
Published: October 2013

We hear vowels produced by men, women, and children as approximately the same although there is considerable variability in glottal pulse rate and vocal tract length. At the same time, we can identify the speaker group. Recent experiments show that it is possible to identify vowels even when the glottal pulse rate and vocal tract length are condensed or expanded beyond the range of natural vocalization. This suggests that the auditory system has an automatic process to segregate information about shape and size of the vocal tract. Recently we proposed that the auditory system uses some form of Stabilized, Wavelet-Mellin Transform (SWMT) to analyze scale information in bio-acoustic sounds as a general framework for auditory processing from cochlea to cortex. This talk explains the theoretical background of the model and how the vocal information is normalized in the representation. [Work supported by GASR(B)(2) No. 15300061, JSPS.]
Identification of ‘‘size-modulated’’ vowels sequences: Effects of modulation periods and speaking rates
Authors: Tsuzaki Minoru , Irino Toshio , Patterson Roy
Published: October 2013

We investigated the temporal dynamics of auditory normalization and size perception by measuring vowel recognition performance using sequences of vowels in which vocal tract length was modulated during the sequence. The modulation of speaker size was achieved by scaling the frequency axis of the transfer function of vocal tract. The temporal modulation pattern was sinusoidal with a period of 16, 32, 64, 128, 256, 512, 1024, 2048, or 4096 ms. Listeners identified sequences of six vowels from four response alternatives. Although the listeners had no experience with size-modulated speech, the percentage of correct responses was never less than 90% for any modulation period. This suggests that the auditory system has an automatic size-normalizing mechanism which does not require training. The listeners had most difficulty with the 256-ms modulation period, independent of the speaking rate of the sequence. This might indicate a limitation of the processing speed for size-normalization. A simulation using Mellin Images did not reveal any obvious reason for the dip in performance with the 250 ms period, which suggests that the limitation is not in the image construction stage. [Work supported by GASR(A)(2) No. 16200016, JSPS.]
A comparative study of varying fan noise mitigation techniques in relation to sustainable design goals
Authors: Overweg Cornelis , Fullerton Jeff L.
Published: October 2013

Green building design promotes effective use of materials and energy, improved indoor environmental quality (IEQ), and enhanced occupant comfort. These ‘‘green’’ goals can occasionally conflict with common acoustical approaches used for fan noise control. A design striving for low noise levels from the ventilation system to benefit occupant comfort can inadvertently introduce elements that are contradictory to other green building objectives. For example, typical fan noise control devices introduce higher energy consumption or less beneficial indoor environmental quality. This paper discusses the acoustical, mechanical, environmental, and relative cost impacts of various fan noise control techniques.
Could animals detect the approaching tsunami?
Authors: Jagannathan Srinivasan , Makris Nicholas , Ratilal Purnima
Published: October 2013

A number of sources report the phenomenon of animals running to safety well before the recent southeast Asian tsunami struck. The phenomenon was apparently observed on both sides of the Bay of Bengal, from Thailand to Sri Lanka. The latter is far from the epicenter of the earthquake. Did the earthquake supply the only warning or is it possible that the tsunami radiated seismo-acoustic signals of sufficient amplitude and frequency for animals to detect and interpret it long before it struck shore? This possibility is quantitatively investigated by solving the coupled hydrodynamic-acoustic equations with a tsunami driving term in a range-dependent ocean acoustic waveguide. Cases where the tsunami is in deep water and on the continental shelf are considered. [The general topic of this research follows from a suggestion made by Herman Medwin.]
Developing a procedure for transmission loss testing of noise control blankets
Authors: Buma Corjan
Published: October 2013

The ASTM E90 test method allows variations of the basic procedure to accommodate diverse products (e.g., build a filler wall to test windows or doors). This paper describes the procedure developed to obtain a sound transmission loss rating for a line of noise-control blankets. The subject blankets are normally attached to an engine housing or used as a pipe lagging. It was originally intended to use the E90 procedure to see the increase in STC rating for a metal substrate without and with the blanket(s). However, this did not provide meaningful data. The sheet-metal substrate and the filler-wall test-opening were modified. Useful 1/3-octave band TL-data were then generated. Review of information publicly available for competitive products disclosed a distinct lack of useful acoustical data. The experience obtained in the study described could serve to further augment the E90 (or other) test procedure.
A selected history of duct mode synthesis
Authors: Posey Joe
Published: October 2013

Attempts to attenuate noise propagating down a duct, with or without flow, must recognize that wall boundary conditions permit only certain spatial wave patterns (modes) to exist. The aircraft noise research community began building mode synthesizers at least thirty years ago in order to study duct propagation and radiation phenomena in a laboratory environment. Lockheed Georgia built a spinning mode synthesizer (SMS) for NASA in the 1970s. NASA used its SMS in a circular flow-duct to validate predictions of mode propagation through constrictions, lined sections, and inlets of various shapes. In the mid-1970s, Penn State created a mode synthesizer as part of a demonstration of active noise control in a circular, no-flow duct. NASA sponsored a series of studies in the 1990s aimed at maturing active control technology for ducted fan noise. Each of these active control systems was essentially a mode synthesizer coupled with a control system to cancel fan-generated noise. NASA is currently building a new mode synthesizer in a rectangular duct to study the effects of high-speed flow and curvature of the duct axis on advanced noise suppression technology. The evolution of mode-generation schemes will be discussed.
Acoustics in mechanical engineering undergraduate core courses: Challenges and opportunities
Authors: Prasad M. G.
Published: October 2013

Generally in an undergraduate curriculum of mechanical engineering, acoustics is not included as a core course. The major core courses deal with mechanics, design, dynamics of machinery, etc. However, engineering aspects of acoustics or noise can be included through elective courses. Given the limited slots for elective courses in a curriculum, it is difficult to run elective courses in acoustics regularly with a required number of students. The challenge is to find innovative ways to include acoustics into core courses so that all students are exposed to the field and its applications. The design and analysis of machine elements such as cams, gears, etc. are always part of core courses. It is in these contexts that the acoustics through noise aspects including multimedia can be introduced. Acoustics as an effect due to vibration as cause can be included in vibration analysis. A core course on system modeling can include acoustics. The integration of acoustical topics not only strengthens the core courses but also prepares the graduating engineer to deal with real problems better. Thus, it is important for academic acousticians to bring acoustics into the core courses. This paper presents some efforts to include the acoustics material in some core courses.
The elements of a comprehensive education for future architectural acousticians
Authors: Wang Lily M.
Published: October 2013

Curricula for students who seek to become consultants of architectural acoustics or researchers in the field are few in the United States and in the world. This paper will present the author’s opinions on the principal skills a student should obtain from a focused course of study in architectural acoustics. These include: (a) a solid command of math and wave theory, (b) fluency with digital signal processing techniques and sound measurement equipment, (c) expertise in using architectural acoustic software with an understanding of its limitations, (d) knowledge of building mechanical systems, (e) an understanding of human psychoacoustics, and (f) an appreciation for the artistic aspects of the discipline. Additionally, writing and presentation skills should be emphasized and participation in professional societies encouraged. Armed with such abilities, future architectural acousticians will advance the field significantly.
Teaching sonar methods and technologies using a practical, real-life research environment
Authors: Fedenczuk Tom , Fryer Patricia
Published: October 2013

The results and current developments of an educational outreach website and CD-ROM which allows students and instructors to follow the day-by-day progress of an ocean research expedition aboard the R/V Thomas G. Thompson are presented. Sonar concepts, techniques, and technologies are explained through daily updates, science objectives, data results, and lesson outlines. As the greatest source of data collected on the expedition, sonar technologies play a large role in the outreach effort. Students are exposed to hullmounted bathymetry data collection instrumentation that includes the EM300 and Hydrosweep, multibeam sonar systems. The concept of deep towed, side scan-sonar is introduced through the DSL-120 system (WHOI). Students are also introduced to sonar technologies incorporated into remotely operated vehicles like Jason II/ Madea. These include the Imagenex 855 scanning sonar, the RDI bottom-tracking Doppler velocity logger, as well as navigational transponders. Each instrument and educational concept is detailed using video, Quick Time Virtual Reality, html text, and/or images. Using a Marisat satellite link, students are able to ask the researchers questions about their work and findings. [Work supported by a supplement to NSF/OCE-0002584 project: Collaborative Research: Studies of Deep-sourced Mud Volcanism in the Mariana Forearc: A DSL120, Jason ROV, and Coring Program.]
Integration discipline acoustical engineering for training specialists in acoustics and close areas
Authors: Zagrai Nickolay , Zakharevitch Vladislav
Published: October 2013

The author’s discipline acoustical engineering was developed. It is suggested to students before studying the core disciplines of professional programs. The contents of discipline are general ideas, requirements and possible realization of engineering decisions using acoustical fields in different areas of design. The principles of achieving goals in the area of acoustical engineering were methodically systematized and common concepts of their realization were formulated.
The impact of variation in low-frequency interaural cross correlation on auditory spatial imagery in stereophonic loudspeaker reproduction
Authors: Martens William
Published: October 2013

Several attributes of auditory spatial imagery associated with stereophonic sound reproduction are strongly modulated by variation in interaural cross correlation (IACC) within low frequency bands. Nonetheless, a standard practice in bass management for two-channel and multichannel loudspeaker reproduction is to mix low-frequency musical content to a single channel for reproduction via a single driver (e.g., a subwoofer). This paper reviews the results of psychoacoustic studies which support the conclusion that reproduction via multiple drivers of decorrelated low-frequency signals significantly affects such important spatial attributes as auditory source width (ASW), auditory source distance (ASD), and listener envelopment (LEV). A variety of methods have been employed in these tests, including forced choice discrimination and identification, and direct ratings of both global dissimilarity and distinct attributes. Contrary to assumptions that underlie industrial standards established in 1994 by ITU-R. Recommendation BS.775-1, these findings imply that substantial stereophonic spatial information exists within audio signals at frequencies below the 80 to 120 Hz range of prescribed subwoofer cutoff frequencies, and that loudspeaker reproduction of decorrelated signals at frequencies as low as 50 Hz can have an impact upon auditory spatial imagery. [Work supported by VRQ.]
The effects of acoustical treatment on lateralization of low-frequency sources
Authors: Ryan Timothy J. , Martens William L. , Woszczyk Wieslaw
Published: October 2013

Recently, the standard of using a single low-frequency driver in stereophonic sound reproduction systems has come into question. Though it is accepted that lateral discrimination and localization of signals is possible well into the subwoofer frequency range, the use of multiple subwoofers in small reverberant rooms remains of questionable value. While inter-aural level differences (ILDs) are negligible at low frequencies, source lateralization is possible at low frequencies by virtue of inter-aural time differences (ITDs). But when such reproduction is attempted in small rooms, strong early reflections and resonances associated with room modes can cause erroneous ITD information to be detected by a listener, thereby compromising a listener’s ability to accurately locate the source of a low-frequency sound. Acoustical treatment can be employed to reduce the level of early reflections and low-frequency ringing associated with sharp resonant modes in small rooms. Such acoustical treatment often results in more accurate reproduction of ITDs, which enables more accurate localization of sound sources in the horizontal plane. This study investigated changes in measured interaural phase differences after a treatment scheme using both diaphragmatic and Helmholtz-style absorbers. The results show the viability of using multiple low-frequency drivers given adequate acoustical treatment of the reproduction space.
Low-frequency interaural cross correlation discrimination in stereophonic reproduction of musical tones
Authors: Kim Sungyoung , Martens William L.
Published: October 2013

By industry standard (ITU-R. Recommendation BS.775-1), multichannel stereophonic signals within the frequency range of up to 80 or 120 Hz may be mixed and delivered via a single driver (e.g., a subwoofer) without significant impairment of stereophonic sound quality. The assumption that stereophonic information within such low-frequency content is not significant was tested by measuring discrimination thresholds for changes in interaural cross-correlation (IACC) within spectral bands containing the lowest frequency components of low-pitch musical tones. Performances were recorded for three different musical instruments playing single notes ranging in fundamental frequency from 41 Hz to 110 Hz. The recordings, made using a multichannel microphone array composed of five DPA 4006 pressure microphones, were processed to produce a set of stimuli that varied in interaural cross-correlation (IACC) within a low-frequency band, but were otherwise identical in a higher-frequency band. This correlation processing was designed to have minimal effect upon other psychoacoustic variables such as loudness and timbre. The results show that changes in interaural cross correlation (IACC) within low-frequency bands of low-pitch musical tones are most easily discriminated when decorrelated signals are presented via subwoofers positioned at extreme lateral angles (far from the median plane). [Work supported by VRQ.]
Hearing levels in US adults aged 20–69 Years: National Health and Nutrition Examination Survey 1999–2002
Authors: Murphy William J. , Themann Christa L. , Franks John R.
Published: October 2013

The National Health and Nutrition Examination Survey (NHANES) is a nationally representative, population-based survey designed to assess the health and nutritional status of the civilian, non-institutionalized US population. Data were collected through a personal interview regarding health history and through physical examination. Earlier NHANES surveys were conducted on a periodic basis; however, in 1999, NHANES began collecting data on a continuing, annual basis. During NHANES I, which ran from 1971–1975, audiometric testing was conducted on adults aged 25–74 years. No subsequent testing of adults was conducted in the NHANES program until 1999, when NHANES began audiometric testing of adults aged 20–69 years. This report examines the hearing levels for adults in the United States and compares them with the hearing data from NHANES I. Hearing levels are grouped by age and are grouped by ethnicity and gender.
Speech intelligibility metrics in small unoccupied classrooms
Authors: Cruikshank Matthew E. , Carney Melinda J. , Cheenne Dominique J.
Published: October 2013

Nine small volume classrooms in schools located in the Chicago suburbs were tested to quantify speech intelligibility at various seat locations. Several popular intelligibility metrics were investigated, including Speech Transmission Index (STI), %Alcons, Signal to Noise Ratios (SNR), and 80 ms Useful/Detrimental Ratios (U80). Incorrect STI values were experienced in high noise environments, while the U80s and the SNRs were found to be the most accurate methodologies. Test results are evaluated against the guidelines of ANSI S12.60-2002, and match the data from previous research.
Auditory evoked potential measurement methodology for odontocetes and a comparison of measured thresholds with those obtained using psychophysical techniques
Authors: Nachtigall Paul E. , Yuen Michelle , Mooney T. Aran , Taylor Kristen
Published: October 2013

Most measurements of the hearing capabilities of toothed whales and dolphins have been taken using traditional psychophysical procedures in which the animals have been maintained in laboratory environments and trained to behaviorally report the sensation or difference of acoustic stimuli. Because of the advantage of rapid data collection, increased opportunities, and new methods, Auditory Evoked Potentials (AEPs) have become increasingly used to measure audition. The use of this new procedure calls to question the comparability of the established literature and the new results collected with AEPs. The results of behavioral and AEP methods have been directly compared with basic audiogram measurements and have been shown to produce similar (but not exactly the same) values when the envelope following response procedure has been used and the length of the stimulus is taken into account. The AEP methods allow possible audiometric opportunities beyond those available with conventional psychophysics including: (1) the measurement of stranded dolphins and whales that may never be kept in laboratories, (2) the testing of stranded animals for hearing deficits perhaps caused by overexposure to noise, and (3) passive testing of hearing mechanisms while animals actively echolocate. [Work supported by the Office of Naval Research and NOAA-NMFS.]
Auditory evoked potential measurements with cetaceans
Authors: Mann David , Cook Mandy , Bauer Gordon , Fellner Wendi , Wells Randy
Published: October 2013

Auditory evoked potentials (AEPs) allow researchers to measure the hearing abilities of animals that would be difficult or impossible to train for behavioral measurements of hearing. The hearing abilities of live-stranded cetaceans and wild dolphins can only be made with AEP techniques. In these situations, time with the animal is often restricted to an hour or less, and there is often little control over the acoustic environment in which the tests are performed. AEP measurements may be made while the animals are in air or in shallow pools. For cetaceans in air, sounds are typically presented with a suction cup jawphone. For cetaceans in water, sounds may be presented in a direct field (with the transducer located at some distance from the test subject) or with a jawphone. In each of these situations it is important to understand how thresholds derived from AEP measurements compare with behavioral hearing measurements. Examples of AEP measurements from wild and live-stranded cetaceans are presented to illustrate their usefulness and the constraints under which these measurements must be made. AEP measurements from bottlenose dolphins in air and in water are also compared with their behavioral audiograms.
Transcranial power M-mode Doppler ultrasound for diagnosis of patent foramen ovale
Authors: Moehring Mark , Spencer Merrill
Published: October 2013

Patent foramen ovale (PFO) is a right-to-left shunt (RLS) which communicates blood from the right to left atrium of the heart. PFO has been associated with stroke and, more recently, with migraine headache. Diagnosis of RLS can be accomplished effectively with transcranial power M-mode Doppler ultrasound (PMD). PMD is a modality which can be performed without the sedation required by the more invasive diagnostic technique using transesophageal echocardiography. PMD for this application consists of 2 MHz pulse Doppler ultrasound with placement of sample gates at 2 mm intervals along the single-transducer beam axis, and 8 kHz pulse repetition rate (PMD100M, Spencer Technologies). Doppler power versus depth is constructed every 4ms, using 33 sample gates. Bubble microemboli injected in the venous system and moving across a PFO present as high intensity tracks on a PMD image, as emboli transit from the heart to the brain and through the observed cerebral vasculature. Use of PMD in this context has been reported in the clinical literature [M. P. Spencer, M. A. Moehring, J. Jesurum et al, J. Neuroimaging 14, 342–349 (2004)]. This talk surveys the basic technical features of PMD for sensing PFO-related showers of bubble microemboli, and how these features provide clues to the severity of PFO.
Frequency-dependent ultrasound transmission through the human skull
Authors: White P. Jason , Clement G. T. , Hynynen Kullervo
Published: October 2013

The development of large-aperture multiple-source transducer arrays for ultrasound transmission through the human skull has demonstrated the possibility of controlled acoustic energy delivery into the brain parenchyma. The individual control of acoustic parameters from each ultrasound source allows for the correction of distortions arising from transmission through the skull bone and also opens up the possibility for electronic steering of the acoustic focus within the brain. To determine the efficacy of frequency modulation with such a device, this study examines the frequency dependence of ultrasound transmission in the range of 0.6–1.4 MHz through a series of seven points on each of three ex vivo human calvaria. Using broadband pulses, it is shown that the reflected spectra from the skull reveal information regarding the transmission energies at specific frequencies. In fact, there exists an inverse correlation between the reflected pressure amplitude and the transmitted pressure amplitude such that, for the frequency range under examination, approximately three local minima in the reflection spectra with the corresponding three peaks in transmission are observed. A noninvasive determination of the most efficient transmission frequency for a localized spatial region on a skull can yield an improvement of up to 3.5-dB in ultrasound intensity transmission.
Measurements of the effect of haemolysis on speed of sound and attenuation through suspensions of red blood cells at 15 MHz
Authors: Hobbs Nicola Z. , Coussios Constantin-C.
Published: October 2013

When blood flows through an artificial environment for prolonged periods of time, the red blood cells are gradually destroyed due to the high shear stresses to which they are exposed. The ability to measure the degree of haemolysis accurately and in real time is becoming increasingly important, especially in the context of organ preservation and of the implantation of heart-assist devices as a long-term method for treating heart failure. A recent study indicated that the backscattering coefficient (BSC) of red cell suspensions containing damaged red blood cells is significantly higher than the BSC of suspensions containing exclusively healthy cells. Using a specially designed acoustic chamber, suspensions containing different proportions of healthy and damaged cells were exposed to 15-MHz ultrasound. A thin tungsten wire immersed in each suspension was used to quantify the speed of sound and attenuation through increasingly haemolysed suspensions. It is intended to utilize a combination of measurements of speed of sound, attenuation and backscattering in order to solve the inverse problem and to develop an on-line, non-invasive device for quantifying the degree of haemolysis in artificial circuits.
Music and science meet at the micro level: Time-frequency methods and granular synthesis
Authors: Truax Barry
Published: October 2013

Musical research over the last century has become increasingly entwined with the areas of acoustics, psychoacoustics, and electroacoustics. One of the most striking results has been to push the frontiers of models of sound and music to the micro level, what is generally termed microsound. At this level, concepts of frequency and time are conjoined by a quantum relationship, with an uncertainty principle relating them that is precisely analogous to the more famous uncertainty principle of quantum physics. A class of methods of sound synthesis and signal processing known as time-frequency models have their basis at this quantum level such that changes in a signal’s time domain result in spectral alterations and vice versa. One such method, granular synthesis and the granulation of sampled sound, produces results by the generation of high densities of acoustical quanta called grains. Such a radical shift has profound implications for not only our models of sound design, but also for the compositional methods that emerge as well as the role of the composer in guiding complex processes. The paper will argue that these models are examples of a class of complex systems exhibiting emergent form that create a new form of virtual music instrument.
Acoustics of the Intonarumori
Authors: Serafin Stefania
Published: October 2013

The Intonarumori were a family of musical instruments invented by the Italian futurist composer and painter Luigi Russolo. Each Intonarumori was made of a wooden parallelepiped sound box, inside which a wheel of different sizes and materials was setting into vibration a catgut or metal string. The pitch of the string was varied by using a lever, while the speed of the wheel was controlled by the performer using a crank. At one end of the string there was a drumhead that transmitted vibrations to the speaker. Unfortunately, all the original Intonarumori were destroyed after a fire during World War II. Since then, researchers have tried to understand the sound production mechanism of such instruments, especially by consulting the patents compiled by Russolo or by reading his book ‘‘The art of noise.’’ In this paper we describe the acoustics of the Intonarumori. Based on such description, we propose physical models that simulate such instruments. The intonarumori’s string is modeled using a one dimensional waveguide, which is excited either by an impact or a friction model. The body of the instrument is modeled using a 3-D rectangular mesh, while the horn is considered as an omnidirectional radiator.
Listening to shower meteors with infrasound
Authors: Edwards Wayne N. , Brown Peter G. , Spurny Pavel , ReVelle Douglas O.
Published: October 2013

Observations of the Leonid and Perseid meteor showers over the last few years in Europe using multiple camera systems, including the European Fireball Camera Network, have shown several bright meteors (abs. magnitudes −8 to −16) passing nearby to the IMS infrasound array in Freyung, Germany (I26DE). Subsequent checks of I26DE data show that these meteors were also detected infrasonically. This combination of optical location of the meteor in flight and microbarometer array beamforming has provided an excellent opportunity to delimit the altitudes at which these infrasound signals are being generated. UKMO temperature and wind data from the UARS satellite has been combined with MSIS and HWM models to reconstruct the acoustic velocity conditions present during observations. Using the reconstructed conditions, geometric ray tracing indicates that the source altitudes lie between approximately 80 to 105 kilometers; array back-azimuths appear to confirm this conclusion. This is extraordinary since meteoroids of this size, at these altitudes in the atmosphere, are in the transitional region from free-molecular flow to continuum flow. With these observations there is now confirmed infrasound from three separate meteor showers; the Leonids, Geminids and Perseids, meaning that meteor shower infrasound is much more common than previously thought.
Modeling volcanic infrasound propagation using the parabolic equation
Authors: Edelmann Geoffrey F. , Drob Douglas P. , Lingevitch Joseph F. , Collins Michael D. , Le Pichon Alexis
Published: October 2013

Infrasound originating from volcanic sources in the 1–4 Hz range is detectable at long ranges by remote monitoring stations. The effects of wind, in addition to the atmospheric sound speed, is non-negligible for the propagation of these signals. Recent developments in parabolic equation (PE) methods are applicable to infrasonic propagation where both wide-angles and high-Mach number atmospheric flows are important. We apply this model to infrasonic data measured from volcanoes in the Archipelago of Vanuatu in Oceania (e.g., LePichon et al., 2005), as well as other potentially active volcanoes. The diurnal variations and seasonal variations in measured pressure amplitudes are modeled in the context of recent multi-year observations of volcanic infrasound. The significance of upper atmospheric tidal amplitudes, range dependence, and prevailing gravity waves structure in these calculations are also considered. [Work supported by ONR.]
Frequency band-importance functions for auditory and auditory-visual speech recognition
Authors: Grant Ken W.
Published: October 2013

In many everyday listening environments, speech communication involves the integration of both acoustic and visual speech cues. This is especially true in noisy and reverberant environments where the speech signal is highly degraded, or when the listener has a hearing impairment. Understanding the mechanisms involved in auditory-visual integration is a primary interest of this work. Of particular interest is whether listeners are able to allocate their attention to various frequency regions of the speech signal differently under auditory-visual conditions and auditory-alone conditions. For auditory speech recognition, the most important frequency regions tend to be around 1500–3000 Hz, corresponding roughly to important acoustic cues for place of articulation. The purpose of this study is to determine the most important frequency region under auditory-visual speech conditions. Frequency band-importance functions for auditory and auditory-visual conditions were obtained by having subjects identify speech tokens under conditions where the speech-to-noise ratio of different parts of the speech spectrum is independently and randomly varied on every trial. Point biserial correlations were computed for each separate spectral region and the normalized correlations are interpreted as weights indicating the importance of each region. Relations among frequency-importance functions for auditory and auditory-visual conditions will be discussed.
Innovative /ye/ and /we/ sequences in recent loans in Japanese
Authors: Vance Timothy , Matsugu Yuka
Published: October 2013

The GV sequences /ye/ and /we/ do not occur in Japanese except perhaps in recent loans. Katakana spellings of the relevant loans in authoritative dictionaries are inconsistent, and it is not clear whether native speakers treat them as containing the GV sequences /ye/ and /we/ or as containing the VV sequences /ie/ and /ue/. Native speakers of Japanese with minimal exposure to spoken English were recorded producing some relevant loans in response to picture prompts. The same speakers were also recorded producing some native words containing uncontroversial /ie/ and /ue/ sequences. All the productions are being analyzed acoustically to determine whether they show the expected contrast between GV and VV sequences. A VV sequence is disyllabic (and bimoraic) and should therefore have greater duration and more gradual formant movements than a monosyllabic (and monomoraic) GV sequence. Utterance-initially, a VV sequence should have a LH pitch pattern and should be preceded by a nondistinctive glottal stop, whereas a GV sequence should have a H pitch pattern and should have smooth onset.
Bilinguals reaction times and category goodness judgments in two language-sets: Spanish and English
Authors: Garcia-Sierra Adrian
Published: October 2013

Two monolingual groups (Spanish and English speakers) and one bilingual group (Mexican-American) were compared in reaction times (RTs) and category goodness (CG) ratings during the identification of a synthetic continuum ranging from /ga/ to /ka/. The task consisted of two sessions for the bilingual listeners and one session for the monolingual listeners. Each session was performed in either a Spanish or English language-set. Language-sets were defined by the language used by the researcher and by filler sentences in the language of interest during the identification task (e.g., what do you hear? or Qu fue lo que escuch?). The results show that voicing boundaries were different across all groups including bilinguals in both language-sets (voicing boundary shift). RTs were larger near the voicing boundaries in all groups. Interestingly, bilinguals showed two RT peaks, whereas monolinguals showed only one RT peak. In regard to CG, participants were asked to rate how good exemplar each token was (1=worst; 5=best). Bilinguals rated the synthetic continuum in both language-sets. The scores given by the bilinguals differed in each language-set at VOT values close to the voicing boundary.
Perceptual and production variables in explicating interlanguage speech intelligibility benefit
Authors: Shah Amee P. , Vavva Zoi
Published: October 2013

This study attempts to investigate the importance of the degree of similarity or difference in the language backgrounds of the speakers and listeners, as it interacts differentially in intelligibility judgment of foreign-accented speech (Bent and Bradlow, 2003). The present study attempts to clarify the distinction in the matched and mismatched listening conditions, in context of addressing the overarching question whether auditory exposure to a language alone, without corresponding proficiency in production of that language, can provide a listening advantage. Particularly, do listeners understand accented-English speech spoken by native individuals of the language to which they are exposed to, as compared to listeners without that exposure? Greek-accented English speakers (and native monolingual English speakers) were judged for their speech intelligibility by four groups of listeners (n=10, each): native Greek speakers (matched), Greek-Americans (matched only through auditory exposure to Greek without any corresponding spoken proficiency), native monolingual American-English speakers (unmatched), and a mixed group (mismatched). Pilot data have shown that the intelligibility judgments by Greek-American listeners are intermediate to the native Greeks, and both the American-English and the mixed group. Further data-collection is underway, and will be presented as they bear important theoretical and clinical implications.
Learning to talk: A non-imitative account of the replication of phonetics by child learners
Authors: Messum Piers
Published: October 2013

How is it that an English-speaking 5-year-old comes to: pronounce the vowel of seat to be longer than that of sit, but shorter than that of seed; say a multi-word phrase with stress-timed rhythm; aspirate the /p/s of pin, polite, and spin to different degrees? These are systematic features of English, and most people believe that a child replicates them by imitation. If so, he is paying attention to phonetic detail in adult speech that is not very significant linguistically, and then making the effort to reproduce it. With all the other communicative challenges he faces, how plausible is this? An alternative, non-imitative account of the replication of these features relies on two mechanisms: (1) emulation, and (2) the conditioning of articulatory activity by the developing characteristics of speech breathing. The phenomena above then become no more than expressions of how a child finds ways to warp his phonetic output in order to reconcile conflicting production demands. The criteria he uses to do this make the challenges both of learning to talk and then of managing the interaction of complex phonetic patterns considerably more straightforward than has been imagined.
Quantifying heterogeneity: Attributes, modeling, and inversion
Authors: Imhof Matthias Georg
Published: October 2013

Characterization of reservoir heterogeneity is a necessary step in reservoir delineation, characterization, and modeling. Reservoir heterogeneity can be described deterministically, statistically, or with reservoir-forming geologic processes. Deterministic heterogeneity models are easy to build, but may have insufficient resolution and may not provide enough insights into the reservoir and its properties. The parameterization of stochastic heterogeneity models is nontrivial. Seismic data can be used to determine geostatistical parameters or to refine the geometry parameters used for Boolean modeling. The geostatistical parameters (ranges and orientations) are obtained from seismic heterogeneity attributes measuring the second-order statistics contained in small seismic datacubes. Seismic heterogeneity relates to acquisition and processing artifacts, structure, or stratigraphy and lithology. Seismic data could also be used as additional constraints in Boolean reservoir models which allows both construction of conforming reservoir models and optimization of the geometry parameters to reduce the misfit between model and observations. Reservoirs could also be built by reconstructing their formation and evolution based on mathematical descriptions of processes such as sediment erosion, transport and deposition, compaction, deformation, subsidence and uplift, etc. The process parameters, e.g., rates of sediment input and transport, compaction, or subsidence, could be estimated by inversion of seismic and geologic data.
On the relationship between sea state and the coherent-to-incoherent intensity ratio for high frequency, shallow water propagation
Authors: Roux Philippe , Kuperman William A. , Culver R. Lee , Lutz Steven D. , Bradley David L. , Stevenson Mark
Published: October 2013

A 29-element source array and 32-element receiver array have been deployed in shallow water to investigate various aspects of the acoustic channel. Both arrays spanned much of the water column. Source-receiver range was 800 m, and 3.5 kHz pulses were transmitted using one source at a time and recorded on all elements. In this analysis, we compare the ratio of coherently to incoherently averaged intensities for each source-receiver pair, and averaged over all such pairs, to measure surface roughness. We find that the coherent-to-incoherent intensity ratio decreases with time after the direct path arrival, and that the slope becomes more negative as wind speed and thus surface roughness increases. A simple model for signal phase variation induced by surface scatter shows a direct relationship between the degree of phase variation and wind speed. The relationship between the slope of the coherent-to-incoherent intensity ratio and a physics-based model of incoherent sea surface forward scatter is also considered. [Work supported by ONR Code 321US.]