bluuebunny/crossref_metadata_2025 huggingface dataset:
Heuristics Structure and Pervade Formal Risk Assessment
Authors: MacGillivray Brian H.
Published: October 2013

Lay perceptions of risk appear rooted more in heuristics than in reason. A major concern of the risk regulation literature is that such “error‐strewn” perceptions may be replicated in policy, as governments respond to the (mis)fears of the citizenry. This has led many to advocate a relatively technocratic approach to regulating risk, characterized by high reliance on formal risk and cost‐benefit analysis. However, through two studies of chemicals regulation, we show that the formal assessment of risk is pervaded by its own set of heuristics. These include rules to categorize potential threats, define what constitutes valid data, guide causal inference, and to select and apply formal models. Some of these heuristics lay claim to theoretical or empirical justifications, others are more back‐of‐the‐envelope calculations, while still more purport not to reflect some truth but simply to constrain discretion or perform a desk‐clearing function. These heuristics can be understood as a way of authenticating or formalizing risk assessment as a scientific practice, representing a series of rules for bounding problems, collecting data, and interpreting evidence (amethodology). Heuristics are indispensable elements of induction. And so they are not problematicper se, but they can become so when treated as laws rather than as contingent and provisional rules. Pitfalls include the potential for systematic error, masking uncertainties, strategic manipulation, and entrenchment. Our central claim is that by studying the rules of risk assessmentquarules, we develop a novelrepresentationof the methods, conventions, and biases of the prior art.
Caseload, management and treatment outcomes of patients with hypertension and/or diabetes mellitus in a primary health care programme in an informal setting
Authors: Sobry Agnes , Kizito Walter , Van den Bergh Rafael , Tayler‐Smith Katie , Isaakidis Petros , Cheti Erastus , Kosgei Rose J. , Vandenbulcke Alexandra , Ndegwa Zacharia , Reid Tony
Published: October 2013

Objective

In three primary health care clinics run by Médecins Sans Frontières in the informal settlement of Kibera, Nairobi, Kenya, we describe the caseload, management and treatment outcomes of patients with hypertension (HT) and/or diabetes mellitus (DM) receiving care from January 2010 to June 2012.

Method

Descriptive study using prospectively collected routine programme data.

Results

Overall, 1465 patients were registered in three clinics during the study period, of whom 87% were hypertensive only and 13% had DM with or without HT. Patients were predominantly female (71%) and the median age was 48 years. On admission, 24% of the patients were obese, with a body mass index (BMI) > 30 kg/m2. Overall, 55% of non‐diabetic hypertensive patients reached their blood pressure (BP) target at 24 months. Only 28% of diabetic patients reached their BP target at 24 months. For non‐diabetic patients, there was a significant decrease in BP between first consultation and 3 months of treatment, maintained over the 18‐month period. Only 20% of diabetic patients with or without hypertension achieved glycaemic control. By the end of the study period, 1003 (68%) patients were alive and in care, one (<1%) had died, eight (0.5%) had transferred out and 453 (31%) were lost to follow‐up.

Conclusion

Good management of HT and DM can be achieved in a primary care setting within an informal settlement. This model of intervention appears feasible to address the growing burden of non‐communicable diseases in developing countries.
Experimental and Numerical Investigation of Heated Band Width for Local Post Weld Heat Treatment of ASME P92 Steel Pipe
Authors: Xu Lianyong , Miao Yi , Jing Hongyang , Han Yongdian , Jiang Yunjian , Tian Xuhai , Gao Jie'an
Published: October 2013

Local post weld heat treatment (local PWHT) is usually carried out when it is impractical to place the entire component in a furnace or oven, which is an effective way to relax residual stress due to welding. However, there are various international codes or standards that define different criteria for local PWHT and it may bring confusion in engineering applications. In the present study, welding and local PWHT experiments on ASME SA-335 Grade P92 large-diameter pipes were conducted under field conditions. In order to simulate the temperature field distribution of welded joints during the process of local PWHT, a thermal tracking program has been successfully developed using the ansys parametric design language (APDL) and the numerical results agree well with experimental data. Furthermore, a series of pipe models were developed using the finite element method (FEM) and through repeated calculations, optimized numerical values for each pipe's heated band (HB) width and gradient control band (GCB) width were calculated. Through numerical analysis, recommended estimation of heated band width for local PWHT of P92 large-diameter pipes is obtained, which ensures the minimum temperature throughout the soak band.
Numerical Study of the Flow Past a Turbine Blade Tip: Effect of Relative Motion Between Blade and Shroud
Authors: Acharya Sumanta , Moreaux Louis
Published: October 2013

Turbine blade tips are often the most susceptible to material failure due to the high-speed leakage flow and associated large thermal loadings. In this paper, the effect of the blade rotation and relative motion between the blade tip and shroud is studied numerically. Three different simulations have been undertaken: (1) a static case where the blade and the shroud are stationary (used as the reference case) (2) a linearly moving blade (or shroud) and (3) a rotating blade. Comparisons between cases 1 and 2 identify the effects of relative motion, while comparison between cases 2 and 3 delineate the effects of rotational Coriolis and centrifugal forces. Geometric effects were also studied through different combinations of tip gaps and squealer depths with the relative motion and rotational effects included. The calculations were done using a commercial flow solver, Fluent, using a block body-fitted mesh, Reynolds-averaged transport equations and a turbulence model. Results confirm the significant effects of the relative motion between the blade tip and shroud, and indicate that the assumption of pressure-driven leakage flows for blade tips is inappropriate. While rotational forces also play a role, the magnitude of their effects are relatively small compared to the relative motion effects. Geometric effects are also important with the lower tip clearance reducing leakage flow and allowing the tip coolant to migrate towards the SS with relative motion.
Large-Eddy Simulation and Conjugate Heat Transfer Around a Low-Mach Turbine Blade
Authors: Duchaine Florent , Maheu Nicolas , Moureau Vincent , Balarac Guillaume , Moreau Stéphane
Published: October 2013

Determination of heat loads is a key issue in the design of gas turbines. In order to optimize the cooling, an exact knowledge of the heat flux and temperature distributions on the airfoils surface is necessary. Heat transfer is influenced by various factors, like pressure distribution, wakes, surface curvature, secondary flow effects, surface roughness, free stream turbulence, and separation. Each of these phenomenons is a challenge for numerical simulations. Among numerical methods, large eddy simulations (LES) offers new design paths to diminish development costs of turbines through important reductions of the number of experimental tests. In this study, LES is coupled with a thermal solver in order to investigate the flow field and heat transfer around a highly loaded low pressure water-cooled turbine vane at moderate Reynolds number (150,000). The meshing strategy (hybrid grid with layers of prisms at the wall and tetrahedra elsewhere) combined with a high fidelity LES solver gives accurate predictions of the wall heat transfer coefficient for isothermal computations. Mesh convergence underlines the known result that wall-resolved LES requires discretizations for which y+ is of the order of one. The analysis of the flow field gives a comprehensive view of the main flow features responsible for heat transfer, mainly the separation bubble on the suction side that triggers transition to a turbulent boundary layer and the massive separation region on the pressure side. Conjugate heat transfer computation gives access to the temperature distribution in the blade, which is in good agreement with experimental measurements. Finally, given the uncertainty on the coolant water temperature provided by experimentalists, uncertainty quantification allows apprehension of the effect of this parameter on the temperature distribution.
Comprehensive Brachytherapy: Physical and Clinical Aspects.
Authors: Thomadsen Bruce
Published: October 2013

Comprehensive Brachytherapy: Physical and Clinical Aspects. Venselaar J., Baltas D., Meigooni A., Hoskin P., Imaging in Medical Diagnosis and Therapy, William R. Hendee, Series Editor. CRC/Taylor & Francis Group, Boca Raton, FL, 2013. Hardback 535 pp. Price: $199.95. ISBN: 9781439844984.
Mutual inductance between piecewise-linear loops
Authors: Cristina Barroso Ana , Silva J. P.
Published: October 2013

We consider a current-carrying wire loop made out of linear segments of arbitrary sizes and directions in three-dimensional space. We develop expressions to calculate its vector potential and magnetic field at all points in space. We then calculate the mutual inductance between two such (non-intersecting) piecewise-linear loops. As simple applications, we consider in detail the mutual inductance between two square wires of equal length that either lie in the same plane or lie in parallel horizontal planes with their centers on the same vertical axis. Our expressions can also be used to obtain approximations to the mutual inductance between wires of arbitrary three-dimensional shapes.
An integrated acoustic modeling infrastructure for underwater noise impact assessment
Authors: Hannay David E. , Racca Roberto G.
Published: October 2013

When industrial activities such as underwater dredging or seismo-acoustic surveying are planned near ecologically sensitive areas, effective forecasting of the associated sound levels is often necessary to allow effective noise management planning and to satisfy permitting requirements. To this end a comprehensive software application, the Marine Operations Noise Model, was developed to enable the estimation of aggregate noise levels from complex operations involving numerous activities over extended regions. The softwares architecture includes a specially adapted Parabolic Equation propagation model, a database of field measured spectral source levels from a wide range of industrial vessels, a run module that coordinates modelling and summing of sound from multiple sources, and a GIS interface for the definition of operational layouts and the display of noise level contours on area maps. This application has been used in the planning and regulatory approval process for future pipeline and offshore platform installation activities to take place in the proximity of marine mammal habitats. Its accuracy in this context was validated through an extensive program of acoustic monitoring of similar activities taking place in a nearby location over the course of a prior construction season.
Acoustic design for Teatro Sesc Pinheiros
Authors: Nepomuceno Jose Augusto , McCreery Anthony
Published: October 2013

Sesc is a non-governmental social organization to promote culture, sport and education in Brasil. Among its facilities there is the new Sesc-Pinheiros center with a multipurpose theater seating 1000. Due to changes in the planned use of the theater during construction, Acustica & Sonica was hired by the contractor Mendes Junior to adjust and improve the room acoustics and noise control design of the theater. The original design was modified by adding adjustable acoustical systems, changing in the ceiling and balcony shaping, and revising the specification of all finish materials. The room acoustics modifications followed the recommendations of Akustiks, acoustical consultants from South Norwalk, Connecticut, USA. A concert shell was designed and fabricated to allow the use of orchestral music. An open shell concept was used. The new hall has received excellent critics from pianists, conductors and players, and is rated among the best in the country. Acoustical measurements were performed. The measured values have been compared with the results of a computer model carried out by Acustica & Sonica for this project and they are consistent. [The authors would like to thank Mendes Junior, Sesc, Bengt-Inge Dalenbck and Christopher Blair of Akustiks for their support.]
Evaluation and optimization of acoustical environments in eating establishments
Authors: Razavi Zohreh , Hodgson Murray
Published: October 2013

Complaints from hard-of-hearing faculty members at UBC about communicating verbally in one of the upscale restaurants on the campus led to a study of acoustical environments in eating establishments and how to optimize them. Speech intelligibility and speech privacy are important considerations in the design of eating establishments; however, they are commonly overlooked. In this preliminary research, three bistros were considered. Physical measurements were done and associated acceptability criteria applied to evaluate the environments. The noise exposures of employees and customers were measured and compared to maximum permitted occupational limits. Worker noise exposures were in the range 80–84 dBA. Customers were often exposed to levels over 75 dBA; especially at lunchtime it exceeded 80 dBA. The CATT room-acoustical prediction model was used to study the physical and acoustical factors that affect the acoustical environments in eating establishments and how optimize them. The effect of facility modifications, including the use of sound-absorbing wall panels, lowered and improved acoustical ceilings, and partial barriers between tables were predicted.
Finite-sized sources in the presence of boundaries
Authors: MacGillivray John R. , Sparrow Victor W.
Published: October 2013

Many methods of auralization convolve a source signal (e.g., cello recorded in an anechoic room) with a room’s impulse response (which has been computed using method of images, ray tracing, etc.). Many instruments are finite-sized sources because they produce music having frequencies where the product of the wavenumber and the instrument’s characteristic length is not small. Sound produced by a finite-sized source in the presence of boundaries can include scattering and diffraction, resulting from the presence of the source in its own field. These effects are not accounted for by the auralization types mentioned above. A geometrically simple example of a finite-sized pulsating sphere in the presence of a rigid infinite boundary is solved using the translational addition theorem for spherical wave functions (TATSWF). Using TATSWF, the original problem is solved by replacing the rigid infinite wall with an image of the finite-sized sphere. This is a surprisingly complicated problem to solve, given the simple geometry, and serves to illustrate how a source can perturb its field when near a boundary. Examples are presented for which significant changes in the pressure magnitude occur. [Work supported by the Applied Research Laboratory, Penn State.]
Image guided acoustic hemostasis
Authors: Burgess Sean , Zderic Vesna , Vaezy Shahram
Published: October 2013

Previous studies have shown that high intensity focused ultrasound (HIFU) can successfully control visible bleeding from solid organ injuries. This study investigates the ability of ultrasound image-guided HIFU to arrest occult hemorrhaging in the posterior liver parenchyma using a pig model. The image-guided HIFU device consisted of an intraoperative imaging probe and a spherically-curved HIFU transducer with focal length of 3.5 cm, frequency of 3.23 MHz, and focal acoustic intensity of 2350 W/cm2. A total of 19 incisions (14 HIFU-treated and 5 control incisions) were made in five pig livers. The incisions were 30 mm long and 7 mm deep with HIFU application occurring within 20 s of making an incision. Hemostasis was achieved in all treated incisions after a mean ± SD of 65±15 s of HIFU application. The mean blood loss rate of the control incisions initially and after seven minutes was 0.268 and 0.231 mL/s, respectively. Subsequent histological analysis showed coagulative necrosis of liver tissue around the incision which appeared to be responsible for hemostasis. Ultrasound image-guided HIFU offers a promising method for achieving hemostasis in surgical settings in which the hemorrhage site is not accessible.
Shear wave interferometry, an application of sonoelastography
Authors: Wu Clark Z. , Parker Kevin J.
Published: October 2013

Sonoelastography is an ultrasound imaging technique where low-amplitude, low-frequency (LF) vibration is detected and displayed via real-time Doppler techniques. When multiple coherent shear wave sources exist, shear wave interference patterns appear. Two shear wave sources at the same frequency create hyperbolic shaped interference patterns in homogeneous, isotropic elastic media. Shear wave speed can be estimated from the fringe separation and the source frequency. If the two sources are driven at slightly different sinusoidal frequencies, the interference patterns no longer remain stationary. It is proven that the apparent velocity of the fringes is approximately proportional to the local shear wave velocity. With this approach, local shear wave speed in elastic media can be estimated. In addition, with a single shear wave source at frequency f and the ultrasound probe externally vibrated at frequency f−Δf, a novel type of moving interference between the shear waves and the frame of reference motion is created. The moving interference fringes represent the shape of shear wave wavefronts while traveling at a much slower speed. This approach provides a real-time visualization of shear wave propagation and local wave speed estimation from which local stiffness is inferred. [Work supported by NIH.]
Magnetic resonance elastography
Authors: Ehman Richard , Manduca Armando
Published: October 2013

The goal of our research is to develop MRI-based methods for assessing the mechanical properties of tissues in vivo. We have focused on a novel MRI technique for visualizing propagating acoustic shear waves [Science 269, 1854–1857 (1995)]. Suitable dynamic shear stress for Magnetic Resonance Elastography (MRE) can be generated by surface drivers, inertial effects, acoustic radiation pressure, or endogenous physiologic mechanisms. The MRE acquisition sequence is capable of visualizing cyclic tissue motion of less than 1 micron in displacement amplitude, with imaging times ranging from 100 ms to several minutes. Inversion algorithms based on continuum mechanics are used to process the acquired data to generate maps of mechanical properties such as depict stiffness, viscosity, attenuation, and anisotropic behavior. We have applied MRE to assess specimens of a variety of tissues, ranging in stiffness from lung to cartilage. Human studies have demonstrated that it is feasible to apply MRE to quantitatively image the mechanical properties of skeletal muscles, gray and white matter in the brain, thyroid, kidney, liver, and skin. Our preliminary clinical studies have to date applied MRE to observe changes in tissue mechanical properties in patients with breast, brain, and thyroid tumors, liver fibrosis, and diffuse diseases of skeletal muscle.
A multimode sonic and ultrasonic diagnostic imaging system with application to peripheral vascular characterization
Authors: Spohnholtz Todd , Royston Thomas J. , Yazicioglu Yigit , Martin Bryn , Loth Francis , Bassiouny Hisham
Published: October 2013

Ultrasound (US) medical imaging technology is enhanced by integrating a simultaneous noninvasive audible frequency measurement of biological sounds that could be indicative of pathology. Measurement of naturally-occurring biological acoustic phenomena can augment conventional imaging technology by providing unique information about material structure and system function. Sonic phenomena of diagnostic value are associated with a wide range of biological functions, such as breath sounds, bowel sounds, and vascular bruits. The initial focus of this multimode technology was to provide an improved diagnostic tool for common peripheral vascular complications that result in transitional or turbulent blood flow, such as associated with arteriovenous (AV) grafts and stenoses in common carotid and other arteries due to plaque buildup. We review: (1) the development the multimode system by combining a commercial US system with a novel sonic sensor array and associated instrumentation, and (2) the evaluation of its capability via controlled phantom models of basic subsurface sound sources/structures, as well as simulations of constricted peripheral blood vessels. [Work supported by NIH EB002511 and HL55296, and Whitaker Foundation BME RG 01-0198.]
Assessing multi-source noise environments with an ‘‘equally annoying’’ exposure summation model
Authors: Schomer Paul
Published: October 2013

Miedema [J. Acoust. Soc. Am. 116, 949–957 (2004)] posits an ‘‘equally annoying’’ energy summation model for assessing annoyance in areas exposed to multiple differing noise sources. His ‘‘proof’’ is a theorem. Since his model fits the requirements of the theorem, he states that this ‘‘proves’’ that his model is correct. While it may be true that meeting the conditions of the theorem is a necessary condition, it is not a sufficient condition. From a psycho-acoustical standpoint, the Meidema model is very complex and not really believable. Moreover, it fails to address differences between types of aircraft, types of operation, types of motor vehicle, etc. An ‘‘equally annoying’’ exposure summation model, presented here, is psycho-acoustically much simpler and better satisfies the same theorem conditions because it better satisfies the independence requirement.
Influence of buried objects on the dynamic nonlinearity of inhomogeneous materials
Authors: Attenborough Keith , Qin Qin , Jefferis Jonathan , Heald Gary
Published: October 2013

Donskoy et al. [J. Acoust. Soc. Am. 111, 2705–2714 (2002)] and Korman et al. [J. Acoust. Soc. Am. 116, 3354–3369 (2004)] have shown that the nearby presence of compliant buried objects results in a significant nonlinear response in the spectrum of surface vibration induced by acoustic excitation. The latter have suggested that there is a strong connection with the inherent Nonlinear Mesoscopic Elasticity (NME) of inhomogeneous materials. Laboratory experiments are reported that investigate the comparative NME of granular and fibrous materials and the variation observed between several states of a single material (sand) subject to high sound pressure levels in the frequency range 100 Hz to 2 kHz. Fiberglass and gravel are shown to have strong inherent nonlinearity whereas wet compacted sand has relatively little. In both two-tone and single tone experiments, it is shown that, the presence of buried objects may enhance or reduce the inherent NME of the embedding medium. In cases where the NME is enhanced, compliant buried objects have a greater effect than relatively stiff objects. [Work supported by DSTL, UK.]
Application of time-reversal focusing in elastic wave propagation to buried object detection
Authors: Norville Pelham D. , Scott Waymond R.
Published: October 2013

Time-reversal focusing is a technique for focusing energy both spatially and temporally to a single desired point. First studied in fluid media, additional studies have demonstrated the applicability of time-reversal focusing to solid media and elastic wave propagation. A significant difference between time-reversal and other focusing methods is time-reversal focusings immunity to the variation of wave speeds and the effects of scattering objects within the medium. In the detection of buried objects, this feature is paramount where wave speed variations and clutter are common in the region to be searched. The effectiveness of time-reversal focusing is investigated for a variety of configurations of scattering objects. Fields of uniform objects are examined as well as distributions of randomly shaped clutter, and changes in the propagation medium. Both experimental and three-dimensional numerical results are presented. In previous studies, a phenomenon of super-resolution caused by high-order scattering has been observed where focusing exceeds the diffraction limits of the excitation array. The extent of super-resolution is evaluated for the various configurations of scattering objects in an elastic medium. [Work supported by ARO.]
About the neglected auditory abilities within psychological tests of intelligence
Authors: Papenbrock Jenny , Seidel Kristin , Weis Susanne , Suess Heinz-Martin
Published: October 2013

Auditory abilities play an important role in human intellectual abilities. In his model of human cognitive abilities Carroll (1993) identified a separate domain of auditory ability. Despite their theoretical and practical relevance, these abilities were mainly excluded in psychological tests. In order to compensate for this lack we developed a test which is intended to complement existing intelligence tests. To measure general auditory abilities already existing materials (Stankov and Horn, 1980) were used along with newly developed auditory tasks. Our test includes nonverbal tasks containing only tones as well as auditory textual tasks using spoken words. We expect that the auditory tasks measure a separate ability and therefore can make an important contribution to complement already existing intelligence tests. To demonstrate that the test is able to measure different aspects of auditory abilites pure tone tasks should be distinguishable from auditory textual tasks. 120 subjects worked on the auditory test as well as on a well-established test of intelligence (Test for the Berlin Intelligence Structure Model, BIS-4; Jger, S & Beauducel, 1997) which operates with written, numerical and figural material. Main results of our study are reported and implications for future research concerning psychological ability tests are discussed.
Speech understanding in noise: Contributions of compressive nonlinearities in the basilar-membrane response
Authors: Horwitz Amy R. , Ahlstrom Jayne B. , Dubno Judy R.
Published: October 2013

The contribution of compressive nonlinearities in the basilar-membrane response was assessed by measuring speech recognition in noise as a function of noise level and growth of masking for tones. Consonant recognition was measured in interrupted noise at overall masker levels of 47–77 dB SPL. Additionally, thresholds for a 10-ms, 2.0-kHz tone were measured in a masker ranging in level from 40 to 85 dB SPL and centered at 1 kHz. Subjects were younger and older adults with normal hearing. With speech at a constant level and the masker level varying, it was hypothesized that the response of the basilar membrane to the masker would be linear at lower levels and compressed at medium to higher levels, resulting in less effective masking at higher masker levels. Consistent with the hypothesis, differences between observed and predicted consonant-recognition scores, determined using AI calculations, varied as a function of masker level, especially for younger subjects. At lower masker levels, observed scores declined as predicted as masker level increased; with further increases in masker level, scores declined less than predicted. For tonal growth-of-masking functions, breakpoints were correlated with quiet thresholds: both were significantly higher for older than younger subjects. [Work supported by NIH/NIDCD.]
Utilizing different channels for multiple inputs in cochlear implant processing
Authors: Kwon Bom Jun
Published: October 2013

While cochlear implants successfully provide auditory sensation for deaf people, speech understanding through the device is compromised when there is a background noise or competing sounds, partly due to implant users’ reduced ability in auditory grouping. The present study investigates whether providing multiple streams of input on different channels would facilitate auditory grouping, thereby assisting speech understanding in competing sounds. In acoustic hearing, presenting two streams of input (such as speech and noise) in spectrally separate channels gener- ally facilitates grouping; however, in electric hearing it is difficult to predict and separating them could lead to a negative result, because channel interactions inferred from the excitation patterns are severe and the actual amount of electric current for the noise delivered to the cochlea would be much higher for a given SNR, therefore contaminating the target more effectively. Results from consonant identification measured in a variety of speech/noise conditions (same/different channels) indicate that speech understanding generally improves with separate channels, implying that implant users appear to extract speech information on the basis of spatial (channel) separation, easily overcoming the distracter from the adjacent channels with higher intensity. This also proposes a new measure of channel interactions based on auditory grouping.
Comparison between control strategies for active constrained layer damping treatment to control the sound radiation from a vibrating structure
Authors: Zheng Hui , Lu Chun , Lee Heow Pueh
Published: October 2013

A comparative study is presented of three control strategies for active constrained layer damping (ACLD) treatments to control the sound radiation from a vibrating planar structure. The first control strategy is one commonly used in most existing studies of ACLD for structural vibration control; i.e., the error signal to be minimized for the controller is the vibration response sensed by point transducers, and a proportional derivative controller is employed where the sensor signal and the voltage output is related by real-valued feedback gains. The second control strategy is similar to the first, except that the real-valued control gains are substituted by complex-valued ones. In the third control strategy, the discrete structural acoustic sensing approach is introduced for observing the sound radiation from the structure, and the estimated sound power constitutes the controller input. The control gains aiming to reduce the sound radiation from a simply-supported beam are optimized respectively for the three control strategies, and the control performances are compared. Numerical results show that using the complex-valued control gain in the controller design is always better than using real-valued gain. Furthermore, the ACLD treatments adopting the third control strategy require lowest control efforts.
Whole body vibration measurements on forklift trucks
Authors: Behar Alberto , Libich Steven
Published: October 2013

Data on acceleration values on forklift trucks related to Whole Body Vibration are notably missing in the literature. Although there are several standards that provide guidance on how measurements have to be performed, they are somehow conflicting and difficult to implement since they require simultaneous measurement and processing of data in the three axes, x, y and z. Standards also provide limit values for safety of the personnel exposed to the vibrations. The development of new instruments has made these kind of measurements much easier to perform and to interpret the results, since they include filters following the standards and allow for the use of tri-axial accelerometers. This paper describes measurements done on 11 forklift trucks in a real-life situation, while performing tasks normal for their use. The trucks are of the standing-operator type. The accelerometers were mounted on the body of the truck, so that vibrations were representative for what the operators were exposed to. The three-axes orientation of the accelerometer were taken into account. The paper will present results of the measurements and their assessment following the existing ISO and BS Standards.
Comparison of hearing loss compensation algorithms using speech intelligibility measures
Authors: Ramani Meena , Harris John G. , Holmes Alice E. , Skowronski Mark , Powell Sharon E.
Published: October 2013

Sensorineural hearing loss includes loss of high-frequency sensitivity which results in decreased speech intelligibility. The loss cannot be compensated by inverting the audiogram because of the non-linear effects of sensorineural hearing loss (frequency smearing, decreased dynamic range, decreased time-frequency resolution). Several non-linear compensation schemes exist (Half-gain, POGO, NAL-R, Fig. 6, DSL and LGOB) and this paper provides a comparison of those using the objective Perceptual Evaluation of Subjective Quality (PESQ) score and the subjective Hearing In Noise Test (HINT). The listening tests were run on 15 unaided hearing impaired listeners as well as 15 normal hearing listeners using a simulated hearing loss algorithm. These results show marked improvement in intelligibility for the compensated speech over the normal speech for both normal and hearing impaired adults.
A comparative study of perceived, predicted, and measured speech intelligibility
Authors: Hermes Michael E. , Carney Melinda J. , Cheenne Dominique J.
Published: October 2013

Intelligibility metrics were obtained using a variety of methods in a gymnasium that serves as a place of worship. A word list trial, a computer model, and a computer-based %Alcons test provided the data. The results were compared in order to gauge their relative accuracy. The data from the %Alcons testing were found to be unreliable, but a direct relationship was established between the mean word list test scores and the results gathered from the computer model. This relationship allowed for a translation of the scores to %Alcons.
A statistical model for prediction of functional hearing abilities in real-world noise environments
Authors: Soli Sigfrid , Laroche Chantal , Giguère Christian , Vaillancourt Véronique
Published: October 2013

Many tasks require functional hearing abilities such as speech communication, sound localization, and sound detection, and are performed in challenging noisy environments. Individuals who must perform these tasks and whose functional hearing abilities are impaired by hearing loss may constitute safety risks to themselves and others. We have developed and validated in two languages (American English and Canadian French) statistical techniques based on Plomps (1986) speech reception threshold model of speech communication handicap. These techniques predict functional hearing ability using the statistical characteristics of the real-world noise environments where the tasks are performed together with the communication task parameters. The techniques will be used by the Department of Fisheries and Oceans Canada to screen individuals who are required to perform hearing-critical public safety tasks. This presentation will summarize the three years of field and laboratory work culminating in the implementation of the model. Emphases will be placed on the methods for statistical characterization of noise environments, since these methods may allow generalization of the model to a wider range of real-world noise environments. [Work sponsored by Department of Fisheries and Oceans Canada.]
Effects of high intensity on recognition of low- and high-frequency speech in noise
Authors: Summers Van , Cord Mary
Published: October 2013

For listeners with normal hearing (NH), speech recognition scores often decrease when intensities exceed moderate levels (rollover is observed). It is currently unclear whether the factors leading to rollover in NH listeners also limit performance for hearing-impaired (HI) listeners at high sound levels. This study aimed at clarifying the stimulus conditions most clearly associated with rollover and whether rollover effects are similar for NH listeners and listeners with mild hearing impairment. In Stage 1, NH and HI listeners heard digitally-filtered sentences and adaptive procedures were used to determine high- and low-frequency bandwidths yielding 70%-correct word recognition in quiet at moderate levels. In Stage 2, broadband and band-limited stimuli (based on the high-, and low-frequency passbands measured in quiet in Stage 1) were tested at moderate levels in background noise. Noise levels were varied adaptively to determine signal-to-noise levels supporting 30%-correct recognition. Stimulus conditions leading to criterion performance at moderate presentation levels in Stage 2 were then retested at higher levels in Stage 3. NH listeners showed larger and more consistent rollover effects for high-frequency than for low-frequency or broadband stimuli. The results for HI listeners showed greater variability but also indicated clear rollover effects for high-frequency stimuli at high levels.
Articulatory and acoustic measurements of vowels in hearing impaired speakers following treatment
Authors: Bacsfalvi Penelope , Bernhardt Barbara
Published: October 2013

The purpose of this study was to examine the relationships between ultrasound tongue shapes, electropalatography (EPG) contacts, formant data, and the perceptual data in the vowels of three hard of hearing adolescents. This pilot study examines the pre- and post-therapy speech of the participants in a 6 week group therapy programme with ultrasound and EPG technologies. Before treatment, participants showed particular difficulty with high vowels and the tense-lax distinction. Recordings were made of 2 males and 1 female with ultrasound and EPG. Three types of measurements were made; formant measurements, EPG tongue palate contacts, and perceptual judgements by experienced speech-language pathology researchers. Initial analysis values showed a change in the direction of EPG contact patterns, and perceptual categories. F1 values decreased and F2 values increased, moving in the direction of typical formant frequencies found in hearing people. Preliminary results of this study support a lingual-articulatory approach to treatment.
The role of fundamental frequency (F0) contours in the perception of speech against interfering speech
Authors: Binns Christine , Culling John F
Published: October 2013

A set of experiments investigated the effect of the F0 contour on speech intelligibility against interfering sounds. Speech Reception Thresholds (SRTs) were measured in dB for sentences with different manipulations of their F0 contours. These manipulations involved either a scaled reduction in F0 variation, or the complete inversion of the F0 contour. Against speech-shaped noise, a flattened F0 contour did not have a significant impact on the intelligibility of speech compared to a normal F0 contour: the SRT for the flattened F0 contour being only 0.7 dB higher. The SRT for the inverted contour, however, was 1.6 dB higher than for the normal F0 contour. When the sentences were played against a single-talker interferer, the overall effect was greater, with a 2.1 dB difference between the normal and flattened conditions, and 3.3 dB between the normal and inverted F0 contours. There was found to be no effect of altering the F0 contour of the interferer, indicating that any abnormality of the F0 contour serves to mask the intelligibility of the target speech, but does not alter the effect of the interfering speech. Future research will investigate the impact on speech intelligibility of similar manipulations of a low-pass-filtered F0 contour.
Effect of two-band dichotic listening for hearing impaired listeners
Authors: Sakamoto Shuichi , Murase Atsunobu , Suzuki Yôiti , Kawase Tetsuaki , Kobayashi Toshimitsu
Published: October 2013

The increase of the upward spread of masking is a phenomenon that is typically observed among sensorineural hearing-impaired listeners. To resolve this problem, dichotic listening, by which an input speech spectrum is split into two complementary parts and is presented dichotically, seems effective to reduce masking between contiguous frequency bands. This study examines effects of simple two-band dichotic listening with a cut-off frequency around and between the typical first and second formant frequencies of the preceding vowel. We measured speech intelligibilities in both quiet and noisy environments (S/N 4 and 0 dB). Three types of vowel-consonant-vowel nonsense monosyllables, of which preceding vowels were /a/, /i/, and /u/, were used as speech stimuli. Results showed that this dichotic processing was effective, especially in relatively high S/N conditions. Moreover, the best dividing frequency was dependent on the preceding vowel. When /a/-consonant-vowel was used, the best dividing frequency was 1.0 kHz (around F1 of Japanese vowel /a/), whereas the best dividing frequency was 0.8 kHz (between F1 and F2 of Japanese vowel /u/) when the /u/-consonant-vowel was used.
A detailed study on the effects of noise on speech reception
Authors: Houtgast Tammo , Dubbelboer Finn
Published: October 2013

The effect of adding continuous noise to a speech signal was studied by comparing, for a series of quarter octave bands, the band output for the original speech and for the speech-plus-noise. Three separate effects were identified. (a) Average envelope-modulation reduction: the original intensity-envelope is, on average, raised by the mean noise intensity, resulting in a reduction of the original modulation index. (b) Random instantaneous envelope fluctuations: on an instantaneous basis, the speech-plus-noise envelope shows random variations, caused by the stochastic nature of the noise, and by the instantaneous changes in the phase relation between the speech and the noise. (c) Perturbations of the carrier phase: in the band output carrier signal the addition of the noise causes random phase changes. By applying signal processing techniques, we were able to either include or exclude each of these three effects separately. The results of intelligibility measurements indicated the following order of importance of the three different effects: (1) the average envelope-modulation reduction, (2) the perturbation of the carrier phase, and (3) the random envelope fluctuations. The results will be discussed in the light of modeling and enhancing (noise suppression schemes) speech reception in noise.
Particle filters for tracking a vehicle through a field of acoustic directional frequency and recording (DIFAR) sensors
Authors: Haug Anton J.
Published: October 2013

For nonlinear/non-Gaussian processes, Bayesian approaches to tracking require integration over probability density functions, which cannot be accomplished in a closed form. Recently, numerical Monte Carlo ‘‘particle filter’’ integration techniques have been developed and applied to tracking problems. However, multidimensional application examples of these techniques have been limited because they require an analytic expression for the likelihood function, which is usually not easy to obtain when the noise is non-Gaussian and not additive. Tracking a vehicle through a field of acoustic DIFAR sensors is such an application. Although the vehicle dynamic model can be linear with additive Gaussian noise, the observation model is inherently nonlinear with observations that contain embedded non-Gaussian noise. For the DIFAR vehicle tracking problem, we will consider large time-bandwidth signals, develop both the dynamic and observation models, and show how the Gaussian additive noise on each DIFAR channel results in non-Gaussian noise embedded in the bearing observations. The likelihood function will then be presented and the performance of several particle filter trackers will be compared with that of an Extended Kalman Filter.
Mode extraction from acoustic backscatter in a waveguide
Authors: Walker Shane , Roux Philippe , Kuperman William A.
Published: October 2013

Recently we introduced a technique for extracting the acoustic modes in a range-independent waveguide from measured data alone without a priori knowledge of the environment. This method requires a Vertical Line Array (VLA) to collect data from a moving broadband point source at a single depth in order to reconstruct the frequency-wavenumber (f-k) structure of the waveguide. Our goal is to apply this technique to the more complicated case of bottom reverberation using the VLA as both a source and receiver. As a broadband signal propagates away from the VLA, inhomogeneities along the water/bottom interface scatter some of the field back toward the VLA, mimicking a moving source. However, ambiguities inherent in assigning ranges to the received signal lead to ambiguities in the f-k structure. As a preliminary step, we remove these ambiguities by applying the technique to individual point scatterers at various known ranges along the bottom. These results lay a foundation from which to approach the problem of modeling the bottom as a distribution of point scatterers at unknown locations. Theory, simulation, and laboratory measurements are presented.
Dependence of detection threshold estimates in rabbit on method of constant stimulus parameters
Authors: Carney Laurel H. , Gai Yan , Abrams Kristina S. , Idrobo Fabio , Harrison John Michael
Published: October 2013

The goal of this study was to estimate behavioral detection thresholds in quiet and noise for subsequent physiological studies of responses to near-threshold stimuli. The difficulty in measuring detection thresholds is maintaining stimulus control of behavior over schedule control. Tracking paradigms are efficient, but the large proportion of trials below threshold weakens stimulus control. The Method of Constant Stimuli controls the proportion of trials below, near, and above the SPL for a given percent correct. Here, percentages of trials at different SPLs and zero intensity catch trials were varied to determine proportions that yielded satisfactory stimulus control by a 500-Hz tone in quiet. Trials were initiated by nose-poke observing responses; a nose-poke reporting response within a 3-s window after tone onset resulted in food reinforcement. Reporting responses in the absence of tones resulted in timeouts. A metric for stimulus control was the ratio of the number of correct detections to the number of responses in the absence of the tone. This ratio was highest when approximately 20% of trials were near the 50%-correct SPL and 80% of trials were 20 dB higher. The ratio was lowest when significant proportions of catch and/or below-threshold trials were included. [Work supported by NIDCD DC-001641.]
Manatees masked thresholds for complex sounds
Authors: Gerstein Edmund , Gerstein Laura , Blue Joseph , Forsythe Steve
Published: October 2013

Acoustical masked thresholds of complex real world sounds were measured with West Indian manatees. Motor boat and species-specific calls were recorded, filtered and played back in a forced-choice two-alternative test. A method of constant stimuli was used to estimate the 50% detection thresholds of peak spectral components. Both white noise and recorded wild ambient spectra were used as continuous background noise for two sets of threshold estimates. Manatee calls were detected at and within both white noise and wild ambient levels. Thresholds for broadband boat noise ranged from 9 to 29 dB above ambient conditions. Thresholds for idling boat noise were the highest. The levels were consistent with the subjects’ auditory limits for the lower frequencies with the spectra. The manatee is well adapted to hear the species specific vocalizations under noisy conditions. The integration of multiple critical bands may result in loudness summation benefits which manatees can exploit at higher frequencies, however, at lower frequencies, near the manatees’ limits of sensitivity, benefits of loudness summation were not apparent.