bluuebunny/crossref_metadata_2025 huggingface dataset:
Noise levels in computer data centers: Potential occupational noise hazard.
Authors: Nobile Matthew
Published: October 2013

The noise levels in modern high-density data centers are encroaching on occupational noise limits, such as those set by OSHA laws in the United States or EC Directives in Europe. This is surprising to many because the high-tech computer data center is not usually thought of as a workplace that can cause hearing damage. Over the past decade two trends have contributed to this. First, high-end servers are being packaged more and more densely into a single rack, where the cooling fans or blowers now have to operate at higher speeds and airflow volumes to properly cool them. Secondly, more and more of these systems are being installed on data center floors, with racks often butted one against the other “as far as the eye can see.” An associated problem is as follows: How to predict ahead of time what the sound pressure levels might be in a data center? This involves solving the following emission-to-immission problem: How to translate the emission sound power levels of individual racks into resulting immission sound pressure levels in the room? This paper will present an initial assessment of the noise exposures that exist in today’s data centers and present some initial modeling results.
Patterns of cross subject correlation in second language learning: Skill structure and feature-level grouping in production and perceptual learning.
Authors: de Jong Kenneth , Hao Yen-Chen , Park Hanyong
Published: October 2013

This study examines the degree to which achievement of accuracy in distinguishing contrasts in one set of segments tends to correlate with achievement of accuracy in a related set of segments across listeners. Forty Korean listeners identified anterior obstruents as produced by four American English speakers before, after, and between instances of the vowel /a/. Accuracy rates for fricatives and stops, differing in voicing and in point of articulation, correlated across the listeners, indicating that some listeners were better at manner distinctions as a class. Similarly, accuracy in different voicing contrasts also correlated across listeners, though only when consonants were in the same prosodic location. Voicing accuracy did not correlate with manner accuracy, indicating that particular listeners were specifically good at particular featural contrasts. The productions of 20 Korean listeners of the same consonants in the same prosodic locations were identified by 10 American listeners. Even though the same range of accuracies was found for production as perception, accuracy for various segments typically did not correlate across talkers. These results suggest that, while perceptual learning tends to generalize across segments along featural lines, production learning is more specific to particular segments.
Acquiring novel perceptual categories in a third language: Bengali-English bilinguals’ perception and learning of Malayalam consonants.
Authors: Gogoi Divya V.
Published: October 2013

The present study examines the acquisition of novel non-native speech contrasts by adult bilingual speakers of Bengali and English. One of the underlying issues in this study is the role that phonetic features may play in the development of new phonetic categories. For instance, features utilized in native contrasts may generalize in the learning of novel non-native contrasts, even if they play a limited or no role in the initial perception of these non-native contrasts [Polka (1992); Harnsberger (1998)]. To explore this feature generalization hypothesis, a high variability consonant identification training paradigm was used with ten Bengali-English bilinguals who learned to identify 4 Malayalam place of articulation contrasts (dental versus retroflex nasals, dental versus retroflex lateral approximants, palatoalveolar versus retroflex voiceless fricatives, and alveolar tap versus retroflex approximant). The bilingual Bengali-English listeners were selected for their extensive experience with the relevant place features (e.g., dental, retroflex, palatoalveolar, and alveolar), though Bengali and English lack any direct correspondents to the Malayalam contrasts. Bilingual performance was analyzed in terms of both patterns of perceptual assimilation as well as rate of acquisition of the novel non-native contrasts.
Adapting second language phonemic perception training to common instructional situations: Initial results.
Authors: Sawallis Thomas R. , Townley Michael W.
Published: October 2013

Although current L2 pedagogy de-emphasizes phoneme-level pronunciation training, laboratory experiments demonstrate benefits from training non-natives in perception of difficult target-language phonemic contrasts. Specifically, evidence shows that learners’ perceptual performance improves (Jamieson Morosan, 1986; Flege, 1995), improvements generalize to new talkers and words (Lively, Logan, Pisoni, 1993), perceptual training triggers production improvements (i.e., without production training, Bradlow et al., 1997), and both perceptual (Lively et al., 1994) and production improvements (Bradlow et al., 1999) are maintained over several months. These laboratory studies typically used intensive protocols, with long sessions, several days per week, for 2–3 weeks. We have adapted such protocols for use in common L2 instructional situations, using short sessions spread over a longer study period, and have begun training Japanese and other Asian students on the English /l-r/ contrast using this new regimen. This paper reports on initial results and some comparisons with studies using the earlier more intense protocols.
A nonsense syllable confusion matrix task in Korean-English bilingual children.
Authors: Yoon Seok-Youn , Johnson Cynthia J. , Allen Jont B.
Published: October 2013

Compared to extensive studies in bilinguals in adults and very young children, very few studies have investigated speech perception in school-aged Korean-English bilingual (KEB) children. Given that English (L2) and Korean (L1) have different contrast systems among consonants and vowels and children have different speech perception processing than adults, school-aged KEB children are expected to have more complicated patterns of L2 perception. The main goal of the present study was to discern which set of L2 sounds are salient enough not to experience interference from L1. Ten KEB children at age 8–13 years were asked to identify 30 nonsense syllables of L2 sounds. The results showed that dissimilar consonants to Korean (i.e., /f,θ/) are most confusing to perceive than similar consonants with familiar contrasts (/p,k,b,g/) next to similar consonants with unfamiliar contrasts (/,,s,z/). More interestingly, perception performance in vowels showed the opposite pattern: a similar vowel (/ε/) was less correctly identified than unfamiliar vowels (/I,æ/). The present study suggests that L2 consonants, which cannot be mapped to any of the L1 sounds, are the most challenging to perceive. Nonetheless, groups of sounds that are patterned together cannot simply be explained with the L1 influence. For example, /f,θ/ are most confusing to KEB as well as English-monolingual listeners (Phatak & Allen, 2007); yet confusion of /b/ with /θ/ is unique only to KEBs.
Model based target depth estimation using received signal statistics.
Authors: Jemmott Colin , Culver R. Lee , Bissinger Brett , Bose Nirmal
Published: October 2013

The overall goal of our research is to develop model based sonar signal processing techniques that utilize predictions of the acoustic field while being robust to environmental variability and uncertainty. Specifically, we are estimating the depth of a target broadcasting a tonal signal in shallow water using a single passive hydrophone. Three different techniques, naïve Bayes, histogram filter, and estimator correlator, are examined. Each is applied to event S5 of the SWellEX-96 measurement that took place in shallow water off the coast of California. The data consist of sinusoidal signals transmitted simultaneously from moving sources at two different depths and received at a bottomed horizontal array. Received signal amplitudes are modeled using random access memory for the two sources at different depths, and these modeling results are used in the design of the target depth estimation algorithms. Thus, the ability of each of the techniques to estimate target depth depends on an accurate representation of the uncertainty in the acoustic field due to propagation effects. Despite each technique requiring different assumptions, general conclusions about their effectiveness to solving this problem can be drawn. [Work supported by ONR Undersea Signal Processing, Code 321US.]
The source characterization study 2007: A detailed three dimensional acoustic field measurement of a seismic airgun array.
Authors: Tashmukhambetov Arslan M. , Ioup George E. , Ioup Juliette W. , Sidorovskaia Natalia A. , Newcomb Joal J. , Stephens James M. , Rayborn Grayson H.
Published: October 2013

In September 2007 the Littoral Acoustic Demonstration Center (LADC) collected acoustic and related data from three moored arrays and ship-deployed hydrophones spanning the full water column to measure the three-dimensional acoustic field of a seismic airgun array. The seismic source vessel shot a series of lines to give a detailed angle and range information concerning the field. The data were collected in the western Gulf of Mexico between the East Break and Alamos Canyon regions. Peak pressures, sound exposure levels, total shot energy spectra, and one-third octave band analyses are measures used to characterize the field. Three dimensional maps of these quantities are generated to show dependence on emission and azimuthal angles and range. Both the direct and indirect fields are characterized. Moveout analysis is done to delineate arrivals and to detect ducted and interface waves. [Research supported by the International Association of Oil and Gas Producers.]
Measurements and verification of two mosques in Saudi Arabia
Authors: Orfali Wasim A. , Ahnert Wolfgang
Published: October 2013

Two prestigious mosques, Holy Haram in Makkah and Prophets Mosque in Medinah, have been selected to investigate their acoustical properties. With portable measurement setup basic parameters like reverberation time, intelligibility numbers, sound level distribution, and others have been measured. This was done with and without a sound system installed at the site. In postprocessing the results have been compared with recommendations developed by us for different mosque sizes. Also, proposals are given for further improvements in the existing sound quality. Finally, suggestions for future newly constructed mosques are derived.
Temporal organization of bullfrog choruses
Authors: Simmons Andrea M. , Simmons James A. , Deligeorges S. D.
Published: October 2013

Choruses of advertisement calls of male bullfrogs (Rana catesbeiana) were recorded at two different ponds with an array consisting of two 4-microphone sensors to locate and identify calling individuals. The array determined the bearing of frogs from two positions located 10 m apart along the edge of the pond. Frogs were segregated and classified as individuals from the cluster of bearing intersections provided by the two sensor units for each note making up the advertisement calls. At one pond, 6 frogs were identified by bearing intersections, and 2 additional frogs, picked up by only one sensor unit, were separately identified from the pitch of their calls. At the other pond, 9 frogs were localized and 3 additional frogs were identified. Some frogs called independently, with coincident calling between pairs occurring at or near chance levels. These frogs usually were located remote from one another in the pond. At both ponds, a group of 2–3 frogs located in relative proximity called in partially overlapping temporal sequences that recurred throughout recording sessions. Members of the group may have to recognize each other acoustically in order to maintain the integrity of the timing sequence across multiple repetitions. [Work supported by NIH and DARPA.]
Geometric methods for real-world imaging problems
Authors: Miller Eric , Boverman Gregory , Guven Emre , Khamed ben hadj Miled Mohamed , Cleveland Robin , Ulker Karbeyaz Basak
Published: October 2013

The extraction of information concerning the internal structure of a medium given sparsely sampled, externally collected data is a ubiquitous problem arising in application areas ranging from the large-scale (geophysical prospecting and environmental remediation) to the small (biomedical imaging and nondestructive evaluation). The sensors used to collect data are equally diverse, encompassing the full spectrum of electromagnetic and mechanical modalities. In spite of the broad variety seen in this class of problems, many share underlying common challenges making the application of core processing methods of potential utility across a range of specific problems. In this talk, we discuss the application of geometric parametrizations to problems we have encountered in geophysical and biomedical imaging problems using optical, ultrasonic, and electromagnetic sensors. Estimating the geometry of a tumor, plume of toxic waste, or lesion created in the process of hyperthermia cancer treatment often reduces the ill-posed nature of the imaging problem and allows for the extraction of parameters directly linked to the application-specific information we seek to recover from the data. We shall discuss three approaches we have used to parametrize shape as well as our experience in applying these methods to real-world data.
Applications of acoustic-wave-field downward continuation to geophysical and medical imaging
Authors: Huang Lian-jie , Fehler Michael , Duric Nebojsa , Littrup Peter
Published: October 2013

We introduce acoustic imaging methods using wave-field downward continuation and describe their application to geophysical imaging and ultrasonic breast imaging. We have developed a number of novel migration imaging methods based on the acoustic-wave equation in heterogeneous media. They have been successfully applied for imaging complex structures beneath buried salt bodies in which the velocity is often more than twice that of the surrounding sediment within the Earth. The length scale in seismic imaging problems is on the order of 100 times of the seismic wavelength. Even though the frequency used in ultrasonic breast imaging is at a few megahertz, which is a million times higher than seismic frequency, its length scale is also on the order of 100 times of the ultrasonic wavelength in the breast. On the other hand, there are many differences between seismic imaging and ultrasonic breast imaging. For example, the sizes of imaging objects are 10–100 wavelengths for seismic imaging but on the order of the wavelength or less for ultrasonic breast imaging. We have successfully applied the wave-equation-based migration methods to ultrasonic breast imaging. We will present imaging examples both in seismic imaging and ultrasonic breast imaging.
Applying geophysical imaging algorithms to nondestructive evaluation problems
Authors: Lehman Sean K. , Fisher Karl A. , Clapp Robert A. , Artman Brad
Published: October 2013

The Center for Subsurface Sensing & Imaging Systems (CenSSIS, www.censsis.neu.edu) has been advancing the concept of ‘‘Diverse Problems-Similar Solutions,’’ whereby imaging, inversion, and tomography (IIT) algorithms developed for one field or physical regime are applied to another. Following this philosophy, algorithms developed for geophysical imaging have been successfully applied to a nondestructive evaluation (NDE) problem in a planar multilayer. The depths and acoustic frequencies of geophysical problems are on the orders of kilometers and sub-hertz, while those of NDE are millimeters and megahertz. Just the same, the propagation phenomenon is entirely wave-based in both cases and thus, algorithms developed for one can be applied to the other. [This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48. UCRL-ABS-216281.]
Gradient-based shape optimization of an acoustic horn
Authors: Noreland Daniel , Bangtsson Erik , Berggren Martin
Published: October 2013

Numerical shape optimization is employed in order to improve the transmission properties of an acoustic horn. Wave propagation in the horn is modeled by the Helmholtz equation, which is solved using a finite element method. The shape is modified by changing the position of the mesh points along the contour of the horn. The optimization uses a quasi-Newton algorithm, with the gradient of the cost function computed by solving the adjoint equation for the discretized forward problem. Key points are the mesh movement scheme and different procedures in order to enforce smooth design updates for a large number of degrees of freedom. Convergence is fast, and the resulting horns have good transmission properties over a wide frequency band.
An efficient reconstruction algorithm for inverse scattering based on sensitivity analysis and adjoint equations
Authors: Feijoo Gonzalo R.
Published: October 2013

A common approach when developing imaging algorithms is to construct a linear model that relates the measured data to the properties of interest in the medium. But often a linear model cannot be constructed due to the relevant physics of the problem under study. In these cases, approaches based on optimal control theory offer several advantages: (1) a unified theory can be constructed to deal with different underlying physics and (2) a generic set of algorithms can be developed to solve the resulting system of nonlinear equations. Nonetheless, these methods tend to be too costly for solving problems but those involving few parameters. In this talk a new efficient algorithm for the inverse obstacle problem is presented without making the usual assumptions of a weak scatterer. The algorithm is based on optimal control theory but, different from other methods, it does not rely on iterative techniques to obtain a solution. Rather, it computes a scalar field which is a first approximation to the location and shape of the objects. This scalar field is easily computed in terms of the incident radiation used to probe the medium and an adjoint field constructed from the measured scattering pattern.
Inferring marine animal characteristics using multi-angle scatter
Authors: Jaffe Jules S. , Roberts Paul L. D.
Published: October 2013

An important goal in using active sonar systems to assess underwater animals in situ is the inference of animal dimension. Although 180-deg backscatter provides an estimate of target reflectivity, in many situations the reflected energy is not easily related to animal size. An additional degree of freedom, rarely exploited, is to measure animal scatter at a multiplicity of angles. Although this is more challenging from a technical point of view, the benefit of this additional information can make it worthwhile. The interpretation of multi-angle scatter from marine organisms can be most easily understood in the context of diffraction tomography. Depending upon the details of the scattering process, in fortuitous circumstances a complete set of angular data can be inverted to compute the three-dimensional scattering potential which can ultimately lead to a complete inversion for animal morphology. In cases where it is impractical to collect a complete set of angular data it is often possible to infer characteristic dimensions of the animal from an analysis of the obtainable multi-angle data. The interpretation of multi-angle scatter data in the context of diffraction tomgraphy therefore presents opportunities to infer ecologically significant information about animal populations.
Ambient noise directivity in the East China Sea: Model/data comparison
Authors: Rouseff Daniel , Tang Dajun
Published: October 2013

In general, the vertical directivity pattern of high-frequency ambient noise is anisotropic. For measurements made beneath a shallow-water mixed layer, the observed noise directivity often displays a trough in the horizontal called the ambient noise notch. This notch develops because noise sources near the sea surface generate sound that propagates at relatively steep grazing angles. The directivity pattern is also generally asymmetric about the horizontal notch. This asymmetry develops because the seabed is an imperfect reflector of sound relative to the sea surface. In the present work, ambient noise data taken in the 1- to 5-kHz band during the 2001 East China Sea Experiment are analyzed and compared to models. The noise notch model integrates three components: an internal wave model, a noise model, and an acoustic propagation model that uses transport theory. It is shown how the depth and width of the observed noise notch are consistent with model predictions when internal waves of moderate strength are included in the calculation. The observed asymmetry in the directivity pattern is consistent with predictions when the correct bottom reflectivity is used. Future ambient noise measurements and tests for the models are described. [Work supported by ONR.]
Comparison of acoustical measurements of demising walls in luxury condominiums and townhomes to illustrate the importance of decoupling the mass layers
Authors: Lilkendey Robert M. , Siebein Gary W.
Published: October 2013

Field Sound Transmission Class (FSTC) tests and acoustical measurements of impact noise from cabinet door and drawer impacts were made of demising walls in a number of multifamily luxury townhomes and luxury condominium tower units due to complaints from residents about noise intrusion from adjacent living units. The demising wall constructions included concrete or cmu with gypsum board attached, gypsum board on wood studs, and gypsum board on metal studs. The results of these measurements will be presented to illustrate the need to decouple the mass layers to maximize the acoustical performance. A case study of one project will be presented showing the effects of incremental changes made to a base wood stud wall with gypsum board on each side (STC 36) in which added mass (STC 44), added mass plus decoupling (STC 62), and decoupling with reduced additional mass (STC 58) were tested in an effort by the developer to strike a balance between acoustic performance and cost.
Acoustic cues for improved speech recognition in combined acoustic and electric hearing
Authors: Kong Ying-Yee , Carlyon Robert P.
Published: October 2013

Speech recognition in noise improves with combined acoustic and electric hearing compared to electric hearing alone. Here, we investigate the contribution of four low-frequency hearing cues (fundamental frequency (F0), first formant (F1), voicing, and glimpsing) to speech recognition in combined hearing. Normal-hearing listeners heard vocoded speech in one ear and low-pass (LP) filtered speech in the other. Three conditions (vocode alone, LP alone, and combined) were tested. Target speech with an average F0 of 120 Hz was mixed with a time-reversed masker sentence (average F0=172 Hz) at three SNRs (5,10,15 dB). The LP speech aided performance at all three SNRs. F1 cues were then removed by replacing the LP speech with an LP equal-amplitude harmonic complex with the same F0 contour as the target speech, and an amplitude that was modulated by that of the target’s voiced portions. The benefits of combined hearing disappeared at 10- and 15-dB SNR, but persisted at SNR=5 dB. The same happened when, additionally, F0 cues were removed by fixing the F0 of the harmonic complex at 150 Hz. The results are consistent with a role for the F1 cue and of voicing and/or glimpsing cues, but not with a combination of F0 information between the two ears.
Source areas of midocean microseismic noise
Authors: Bromirski Peter D.
Published: October 2013

Comparison of microseismic noise data collected at the ocean-bottom Hawaii-2 Observatory (H2O), located midway between Hawaii and California, with wind and wave data shows three frequency bands having different source locations. At frequencies from about 0.3 to 0.5 Hz, the noise spectrum shows a strong correlation with overhead wind speed and direction, implying that this energy is generated locally. Correlation of swell height above H2O with microseism energy at frequencies below 0.3 Hz is generally poor, implying that these signals originate at distant locations. The highest noise levels observed occur in the 0.2- to 0.3-Hz band, apparently resulting from the interaction of waves forced by pre- and postfrontal winds from relatively large coincident storms in the same vicinity. Correlation of the H2O microseism levels with NOAA buoy data, with hindcast wave height data over the North Pacific, and with seismic data from mainland and island stations, defines likely source areas of the 0.1- to 0.2-Hz signals. Most of the microseism energy at H2O between 0.08 and 0.2 Hz appears to be generated by high-amplitude storm waves impacting long stretches of coastline nearly simultaneously. [Work supported by the California Department of Boating and Waterways.]
Enhanced drug delivery with ultrasound and engineered delivery vehicles
Authors: Ferrara Katherine W. , Borden Mark A. , Dayton Paul A. , Kheirolomoom Azi , Kruse Dustin E. , Tartis Michaelann , Lum Aaron F.
Published: October 2013

We demonstrate that local drug delivery can be achieved by ultrasound, combined with engineered delivery vehicles, where the vehicles have a diameter on the order of nanometers to microns. Delivery vehicles can be created from microbubbles with a thickened shell or a lipid shell decorated with drugs, genes, or nanoparticles. Alternatively, liquid-filled nanoparticles can be employed to carry the desired compound. Ultrasound can deflect these vehicles from the center of the flowstream, can fragment the vehicle releasing its contents, and may enhance the uptake of the particle or its contents by cells in the desired region. The ultrasonic mechanisms behind these changes are summarized. The addition of targeting ligands to the shell to improve target specificity is also explored. Methods to measure the effectiveness of local drug delivery, including correlative imaging modalities, binding assays, and cytotoxicity assays, will be described. [The support of NIH CA 103828 is gratefully acknowledged.]
Scattering of high-frequency ultrasound by cells and cell ensembles: In search of the dominant scattering source
Authors: Kolios Michael
Published: October 2013

High-frequency ultrasound (HFU) imaging (in the range of 20–60 MHz) has been recently enabled by advances in transducer technology and electronics. These high frequencies afford greater image resolution, on the order of 40 microns, at the expense of penetration depth, limited to a few centimeters. The associated ultrasound wavelengths of HFU are 25–75 microns, on the order of the size of cells. Therefore, it is hypothesized that at these frequencies ultrasound tissue characterization will provide more meaningful information about the physical characteristics of cells and any changes that occur in their structure during cancer treatment. The late Dr. Frederic Lizzi pioneered ultrasound tissue characterization and the seminal papers he published provided the impetus for this work. Here, backscatter from individual cells and tightly packed cell aggregates of the same cells (emulating tumors) are examined and compared to theoretical models of ultrasound backscatter. Recent work with a series of cells lines with different sizes and physical characteristics will be presented. It will be shown that for in vitro and in vivo experiments, the backscatter signal characteristics best correlate with nuclear size.
Automated coronary plaque characterization with intravascular ultrasound backscatter: In vivo and ex vivo validation
Authors: Vince D. Geoffrey , Nair Anuja , Margolis M. Pauliina , Kirby Stacy L. , Kuznicki Jennifer J. E. , Wang Xiaofeng , Kuban Barry D. , Margolis James R.
Published: October 2013

Atherosclerosis is considered both a systemic and local disease. Current diagnostic tools do not allow adequate in vivo characterization of lesions. Intravascular ultrasound (IVUS) backscatter analysis has displayed the potential for real-time plaque characterization by advanced spectral analysis. One hundred-fifteen plaques from 51 coronary arteries were imaged ex vivo at physiologic pressure, using 20-MHz IVUS transducers. After imaging, the arteries were pressure fixed and matching histology was collected. Regions were selected from histology and corresponding IVUS data were used to build the ‘‘VH’’ plaque classification system using spectral analysis and classification trees. VH images were validated ex vivo by comparison with histology via 407 selected regions that comprised 162 fibrous, 84 fibro-fatty, 69 necrotic-core, and 92 dense-calcium regions. The overall predictive accuracies were 92.9%, 93.4%, 94.3%, and 99.3% respectively, with sensitivities and specificities ranging from 84% to 99%. Reproducibility was assessed ex-vivo and in vivo with two pullbacks of IVUS catheters in each. A semiparametric regression model and the t-test were used to quantify reproducibility, which was high in each case. VH is a robust technique that provides accurate and reproducible information on plaque composition, with considerable potential for assessment of plaque vulnerability in real time.
Ultrasonic and magnetic-resonance spectra in tissue-type imaging for planning and monitoring prostate cancer treatment
Authors: Dasgupta Shreedevi , Feleppa Ernest , Ketterling Jeffrey , Ramachandran Sarayu , Porter Christopher , Arias-Mendoza Fernando
Published: October 2013

No reliable method of imaging prostate cancer currently exists. These prostate tissue-typing studies aim to improve the effectiveness of biopsy guidance and treatment monitoring by developing better imaging methods for identifying cancerous prostate tissue. Success will reduce the false-negative rate of biopsies and treatment side-effects. Ultrasonic (US) radio-frequency (rf) echo-signal data acquired during biopsy examinations were used to compute spectral parameters. These spectral parameters along with clinical parameters, e.g., PSA, were used to train a neural network classifier using biopsy results as the gold standard. Cancer-likelihood scores from a look-up table were used to generate tissue-type images (TTIs). The ROC-curve area for US neural-network-based classification was 0.844±0.018 vs 0.638±0.031 for B-mode-based classification, and the sensitivity of neural-network based classification was superior to that of B-mode-guided biopsies. These classification methods are being extended to include magnetic-resonance spectral (MRS) techniques that use the choline to citrate ratio-to-distinguish cancerous from noncancerous prostate tissue. 3D renderings of prostatectomy histology, US, and MR images show encouraging correlations, and combining MRS parameters with US spectral parameters appears to have potential to further improve prostate-cancer imaging. [Work supported in part by NIH Grant CA053561.]
Documenting visual context for soundscapes
Authors: Lavallee Tim , Catania Vincent , Kull Robert
Published: October 2013

There are several considerations to make when documenting a given soundscape. Not only is the technical sound information important, but the space, receptor, and visual context are important as well. This is primarily important in furthering the ability of sound and soundscape professionals to communicate with architects, planners, and other engineers—and vice versa. A portable digital recording system was assembled and used along a high-end digital camera to document a range of soundscapes. These tests were preformed in urban, suburban, and rural areas at different times and in different contextual settings. Both visual and audio information of a locale were documented. Although this method can be simple or complex, the combination of these two components highlights the human factors that are present for a given soundscape. This will be a discussion of the portable equipment and a presentation of sound recordings, spectra, and photographs of a range of soundscapes. The variety and complexity of soundscapes and the benefits of visual clues to add depth to a given documentation effort will be highlighted.
Correlation functions of temperature and velocity fluctuations in a turbulent atmosphere
Authors: Ostashev Vladimir E. , Vecherin Sergey N. , Wilson D. Keith , Collier Sandra L.
Published: October 2013

von Kármán spectra of temperature and velocity fluctuations are widely used in theories of turbulence and wave propagation in random media, including sound propagation through a turbulent atmosphere. They are probably the simplest generalization of the Kolmogorov spectrum of homogeneous and isotropic turbulence which accounts for the outer scale of turbulence. However, the correlation functions of temperature and velocity fluctuations corresponding to the von Kármán spectra are proportional to the modified Bessel functions and are rather involved. In this paper, we propose to use much simpler correlation functions of temperature and longitudinal velocity fluctuations whose dependence on the distance R between observation points is given by exp(−R2/3/L2/3), where L is the outer length scale. It is shown that the spectra of the proposed correlation functions coincide with the Kolmogorov spectrum in the inertial subrange and are bounded in the energy subrange. For some problems, the proposed correlation functions can simplify analysis of sound propagation through a turbulent atmosphere. Examples of the use of these correlation functions in acoustic tomography of the atmosphere and calculations of the coherence function of a sound field are presented. [Work supported by ARO, Grant DAAD19-03-1-0104.]
Hearing levels in US adults aged 20–69 Years—National Health and Nutrition Examination Survey (NHANES) 1999–2004
Authors: Murphy William J. , Themann Christa L. , Stephenson Mark 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, noninstitutionalized U.S. 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 to 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. In 2004, the sampling from this age group was completed. 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 by ethnicity and gender.
Defining and enhancing attributes for features
Authors: Stevens Kenneth N.
Published: October 2013

We take the view that words are represented in memory as sequences of bundles of binary distinctive features. It is further assumed that each feature is defined by a quantal relation between an articulatory attribute and a corresponding acoustic property that provides acoustic cues to the feature. In the speaking process, other acoustic properties are introduced in addition to the defining acoustic attributes, and these contribute additional cues that enhance the perceptual saliency of the feature. For example, the defining attributes for the voicing feature is the presence or absence of glottal vibration during an obstruent consonant, but there are several possible enhancing properties, such as the presence of aspiration noise and a modified fundamental frequency in the following vowel. In running speech, the saliency of a feature may be in jeopardy, especially when there is interfering noise or when gestural overlap weakens some of the cues, particularly those derived from the defining gesture for the feature. An example is the casual production of batman where the closure for /t/ may be eliminated by gestural overlap, but two enhancing gestures (F2 transition for the alveolar and the glottalization for /t/) are preserved. [Work supported in part by NIH Grant DC00075.]
Possible mechanisms of enhancement and multiplicity of cues
Authors: Xu Yi
Published: October 2013

It has been proposed that phonological contrasts are phonetically realized not only by their primary articulations, but often also by enhancing gestures [Kingston & Diehl ‘‘Phonetic knowledge,’’ Language, 70, 419–454 (1994); Stevens & Keyser, ‘‘Primary features and their enhancement in consonants,’’ Language, 65, 81–106 (1989)]. Meanwhile, enhancement appears to parallel the well-known phenomenon of multiplicity of cues in speech perception [Lisker ‘‘Voicing in English: Acatologue of acoustic features signaling /b/ versus /p/ in trochees.’’ Lang. Speech, 29, 3–11 (1986)]. An interesting question is therefore whether the two are one and the same. By a narrow definition, only articulatory maneuvers not obligated by the articulatory gestures of the phonetic units in question play an enhancing role. Thus not all cues that benefit perception are generated for the sake of enhancement. On the other hand, there may indeed be cases where genuine enhancement occurs, for which a further question is why is it needed in the first place? One possibility is that enhancement is not only for resisting noise in the speech environment, but also for handling the competition among communicative functions that are transmitted in parallel. That is, multiple communicative functions often share the same acoustic/articulatory dimension and such functional crowding may create the need to exploit additional means of encoding. If so, both enhancement and multiplicity of cues could be part of a live process that maintains the effectiveness of speech communication.
Learning to ignore a perceptual cue: Nonnative listeners outperform native listeners
Authors: Broersma Mirjam
Published: October 2013

Native and nonnative listeners categorized /v/ and /f/ at the end of English nonwords. For each participant, the duration of the previous vowel was kept constant, so that it was not informative and sometimes mismatched other information in the signal. Vowel duration was varied between participants. Previously presented results [M. Broersma, J. Acoust. Soc. Am. 117, 3809–3901 (2005)] showed that native English listeners relied strongly on the misleading vowel duration cue. For Dutch listeners, no effect of vowel duration was found. Due to the redundancy of information in the signal, Dutch listeners categorized the contrast more categorically than English listeners. New analyses investigated whether Dutch listeners did not attempt to use vowel duration at all, or whether they learned to ignore the misleading cue more easily than the English listeners did. The results showed that Dutch listeners did use vowel duration initially, but stopped using this cue after very few trials. By the end of the practice part (33 trials) the effect of vowel duration had fully disappeared. The English listeners used vowel duration as a voicing cue throughout the experiment. This suggests that it may be easier to learn to ignore uninformative perceptual cues in a nonnative language than in one’s native language.
A biomimetic robotic system for localizing gunfire
Authors: Deligeorges Socrates , Zosuls Aleksandrs , Mountain David , Hubbard Allyn
Published: October 2013

Using a biomimetic approach, a new method of acoustic signal processing was created which has tremendous advantages in complex acoustic environments. The biomimetic approach was used as the basis for a system to localize and identify sound sources in noisy and reverberant conditions. The algorithms are based on mammalian hearing and mimic the acoustic processing of the auditory periphery and midbrain. The system uses spectro-temporal cues exploited by the auditory system including such features as interaural time difference (ITD), interaural level difference (ILD), spectral profile, and periodicity content. The initial system of algorithms were designed and tested using the EARLAB [earlab.bu.edu] software modeling environment. The system of algorithms was then adapted to a mixed-signal real-time hardware solution and mounted on an iRobot PackBot robotic platform to perform simple behavioral tasks. The integrated system can detect and localize gunfire in a complex, reverberant acoustic environment and orient a camera towards the shooter. Accuracy in field tests with live fire was 1.5 deg in azimuth. The performance of the prototype platform demonstrates the potential of the biomimetic approach and its applications to practical problems for commercial, civilian, and military acoustic processing. [Work funded by ARL:DAAD19-00-2-0004.]
Loudspeaker defect analysis using ultrasonic harmonic characterization
Authors: Galway W. Scott , LaBruzzo Matthew A. , Celmer Robert D. , Foley Daniel
Published: October 2013

This study presents the results of an ongoing investigation of defect detection in transducers. Loudspeaker assembly faults, such as a rubbing voice coil, bent frame, loose spider, etc., have traditionally been detected using experienced human listeners at the end of a production line, or through the use of low-order harmonics for total harmonic distortion measurement. The findings of Thompson et al. [‘‘Higher-order harmonic signature analysis for loudspeaker defect detection,’’ J. Acoust. Soc. Am. 114, 2400 (2003)] described a new method wherein the total energy of high-order harmonics groups (10th through the 20th, or 31st through the 40th), were measured and analyzed. This approach demonstrated the ability to delineate distinct signatures that correlated to the root cause of audible rub and buzz distortions. This paper presents the results of a follow-up study using equipment that collected harmonic data up to 100 kHz. Results are presented for ten 5-in. midrange loudspeakers, in which trends for specific acoustic signatures were correlated to known defects. The use of a computer-based electroacoustic measurement and analysis system using frequencies that are inaudible but beneficial for analysis of defects are discussed. [Work supported by Listen Inc., Boston, MA.]
A phenomenological model for sonic crystals based on artificial neural networks
Authors: Fuster-Garcia Elies , Romero-Garcia Vicent , Sanchez-Perez Juan V. , Garcia-Raffi Luis M. , Sanchez-Perez Enrique A.
Published: October 2013

In this paper we develop a phenomenological model that simulates the acoustic attenuation behavior of sonic crystals. The input of the model is a set of parameters that characterizes each experimental setup and the output is the associated simulated attenuation spectrum. The model consists of a combination of multiresolution analysis based on wavelet functions and a set of artificial neural networks. An optimized coupling of this tool allows us to reduce drastically the experimental data needed and also to have a fast computational model that can be used for technological purposes. [This research has been partially supported by the Generalitat Valenciana (Spain), under Grant GV04B-371, by Comision Interministerial de Ciencia y Tecnologia of Spain, under Grant BFM2003-02302, and by Comision Interministerial de Ciencia y Tecnologia of Spain, Contract Ns. MAT 2003-04993-03.]
Nonlinear behavior of interacting harmonics in audio spectra
Authors: Vijayakumar V. , Eswaran C.
Published: October 2013

In this paper we will show how individual harmonics of a frequency-modulated dynamic audio spectrum undergo interactions. This results in nonlinear behavior of the spectrum. We have illustrated the nonlinear behavior with respect to the number of harmonics and the modulation parameter. It is shown that an audio spectrum containing higher-order harmonics is more susceptible to interation among itself. Musical instrument spectra are used to illustrate this effect and audio samples are provided.
From mono to surround: A review of critical listening room design and a new immersive surround design proposal
Authors: D’Antonio Peter
Published: October 2013

As our critical listening rooms have evolved from mono to stereo to an ill-fated attempt at quad to full surround, many approaches have been taken in the design of these spaces. This presentation will review significant milestones in this evolution including the early compression ceilings, reflective front-absorptive rear, absorptive front-absorptive rear nonenvironment, absorptive front-diffusive rear, spatio-temporal reflection-free zone front-diffusive rear, and reflection-rich zone in front-diffusive rear. Recently there has been a renaissance in the evaluation of the importance of specular and diffuse reflections in auditory perception. The presentation will conclude with a proposal for a new immersive surround environment, which can be described as an ambient anechoic or ambechoic environment. Fully enveloping diffuse room reflections are 30 dB below the direct sound, as in an anechoic environment, yet the room feels ambient, provides precise localization, and offers a creative work environment for recording and monitoring. An example of a proof-of-concept room will be illustrated and described.
An innovative professional music recording/monitoring space
Authors: Massenburg George
Published: October 2013

A new kind of professional recording/monitoring space has been designed and constructed as part of the Blackbird Studio complex in Nashville, Tennessee. The room will be introduced and the early subjective impressions will be discussed. The objective of this new room was threefold: first, to provide a surround mixing space with much-improved virtual source localization over a broader footprint in the space, second, to provide a highly diffuse space for the recording of live music performances by one or more vocalists and/or musicians, and third, to investigate a largely diffuse monitoring environment as it might benefit the quality and/or efficiency of professional music mixing in different formats. This presentation will discuss some of the results and some of the surprise outcomes, including practitioner-reported improvements in quickly attaining comprehensive, surgical equalization of sources, possibly attributable to an environment with somewhat more equal reverb times across the frequency spectrum.
Nanoacoustics: Towards imaging nanostructures using picosecond ultrasonics
Authors: Norris T. B.
Published: October 2013

Coherent acoustic phonon pulses with a peak frequency and bandwidth of the order of 100 GHz can be generated by ultrafast optical excitation of a thin metal film on a crystalline substrate. We demonstrate submicron resolution imaging of surface-grown nanostructures using these picosecond ultrasonic pulses. Ultrafast optical pulses from a Ti:sapphire oscillator are used to thermoelastically excite a patterned 15-nm-thick Al film on a Si substrate. The spatio-temporal diffracted acoustic strain field is measured by time-delayed optical probe pulses on the opposite side of the substrate, and this strain field is used in a time-reversal algorithm to reconstruct the Al pattern. The image resolution is characterized using lithographically defined 1-micron-period Al structures on Si. Straightforward technical improvements should lead to a resolution of at least 45 nm, which will significantly extend the resolution of acoustic microscopy and provide a novel contrast mechanism for nanoscale imaging. To assist the development of this imaging method, we have also made experimental and theoretical studies of the behavior of these coherent acoustic phonon pulses after propagation through millimeter-scale distances in crystalline Si.