bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer model studies to predict qualitative and quantitative measures of speech intelligibility in class rooms
Authors: Kim Hyeong-seok , Siebein Gary , Kreisman Brian , Crandell Carl
Published: October 2013

Computer model studies were used to predict qualitative and quantitative measures of speech intelligibility in classrooms under realistic conditions of background noise and reverberation. Fifteen different acoustical measurements related to speech intelligibility were made at multiple locations in three actual classrooms and in computer models of the classrooms. Speech intelligibility (MRT) tests were given to human subjects in each of the actual classrooms at five signal-to-noise ratios. Speech intelligibility tests were also prepared from aural simulations obtained by convolving anechoic speech tracts with impulse responses obtained in the computer models. Correlations (R2) between acoustical measures made in the full size classrooms and the computer models of the classrooms of 0.92 to 0.99 with standard errors of 0.033 to 7.311 were found. The scores on the speech intelligibility tests given in the actual rooms in the five noise conditions were closely duplicated in the equivalent tests conducted in a sound booth using the simulated speech signals obtained in the computer models. Both quantitative and qualitative measures of speech intelligibility in the actual rooms were accurately predicted in the computer models.
A comparison of computational models for predicting speech intelligibility and speech privacy
Authors: Muehleisen Ralph T. , Beamer C. Walter
Published: October 2013

Speech intelligibility (SI) and speech privacy (SP) are very important considerations in the design of classrooms, auditoria, conference rooms, and offices. Predictions of SI and SP are usually done with simple analytic models using Sabine/Eyring theory or CAD programs such as CATT, EASE or ODEON. In this paper we will compare the predictions of speech intelligibility index (SII), speech transmission index (STI), and privacy index (PI) using analytic theories of Sabine/Eyring and a simplified acoustic radiosity theory, a simple computational model using acoustic radiosity and CAD prediction using CATT acoustics. Predictions will be compared with the results of a similar study by Bistafa and Bradley [J. Acoust. Soc. Am. 109(4), 1474–1482 (2001)].
Sound quality in environment: ‘‘Psychoacoustic mapping.’’
Authors: Genuit Klaus
Published: October 2013

The annoyance due to noise in the environment is often predicted by analysis software which calculates the A-weighted sound pressure level distribution depending on the sound sources and on the sound propagation caused by them. The actual subjective perceived noise annoyance of the environment does not only depend on the A-weighted sound pressure level, but also on the so-called sound quality along with other parameters like the aspects of a soundscape. The question regarding noise annoyance cannot be predicted by the A-weighted sound pressure level alone. The sound quality perceived by the human hearing depends on, among other things, loudness, roughness and sharpness. The previously known methods for the prediction of the spatial A-weighted sound pressure level distribution based on the propagation are not suitable to predict psycho-acoustic parameters in an adequate way. Especially the roughness caused by modulation or the sharpness generated by the contribution of high frequency sound energy at various distances cannot readily be predicted. In the following it will be shown what the requirements are and especially what the challenges are for making such a psychoacoustic mapping.
Community reaction to noise from a replaced bridge span and associated approach
Authors: Donavan Paul R. , Rymer Bruce
Published: October 2013

A newly constructed replacement of the westbound span of the Carquinez Bridge on Interstate I-80 in the San Francisco Bay Area was recently opened for service. Although the traffic volume and mix remained the same as it was before the project, there was a very strong reaction to the noise produced by the new construction from nearby residences. For these residences, the predicted noise levels were only expected to increase by less than 2 dB due to the bridge and its approaches being somewhat closer to the community. The complaints had two aspects: generally higher traffic noise levels and impulsive slaps from the expansion joints in the viaduct connecting the bridge deck to the at-grade roadway. Although clearly audible in the community, the joint slaps did not contribute to any of the common community traffic noise metrics. For noise mitigation, the viaduct surface was ground to reduce overall tire/pavement noise, however, there was concern that by reducing the masking effect of the pavement texture generated noise, the slaps from joints would become even more noticeable and objectionable. The before and after noise measurements and community response are presented and discussed in this presentation.
Ambient noise in Johns Hopkins Hospital
Authors: Busch-Vishniac Ilene J. , West James E. , Barnhill Colin , Hunter Tyrone
Published: October 2013

Although noise in hospitals is widely recognized as a problem, there has been little work to characterize hospital noise reported in the literature. From the literature that does exist, it is clear that noise in hospitals poses problems for patient safety, increases staff stress, and is a leading source of complaints by patients and visitors. It is also clear that few hospitals currently meet the recommended noise limits of the World Health Organization or the US EPA. In this paper we present the first round of results of a noise study at Johns Hopkins Hospital in Baltimore, MD. Some interesting characteristics of the noise include its high level, its unusually flat spectrum through the speech range, and its relative invariability with location.
Pitch/amplitude mismatches in Mandarin
Authors: Davison Deborah S.
Published: October 2013

Pitch and amplitude contours covary in Beijing Mandarin [Sagart (1986)]. Tianjin Mandarin amplitude range of stressed low (L) phonological tones is equal to that of stressed high (H) tones for >50% of L tokens. F0 range for 75–85 dB lexical tonemes T1L and T3LH versus T4HL was 100–158 Hz versus 135–180 Hz, respectively. Dimensions of f0/amplitude range for T1L 75–150 Hz/70–85 dB versus T4’s H 110–180 Hz/70–85 dB were virtually identical: 75 Hz/15 dB versus 70 Hz/15 dB, respectively. Stressed T1L and T3LH low f0’s relatively higher amplitude may compensate for reduced perceptual saliency of low f0. T2‘‘H’’’s [Yip (2002)] pattern resembles T4H assuming T2’s single H tonal target aligns to right rather than left syllable edge (cf. Beijing lexical T2 ‘‘mid-to-high rising tone’’) when fully stressed, hence bimoraic. Tonally unspecified left edge T2 f0 does not correlate with amplitude. Both monomoraic ‘‘toneless-stressless’’ neutral tone T0 syllables preceding stressed T1L and T3LH and lexical T1L and T3LH ‘‘sandhi-changed’’ to LH and H preceding stressed T1L and T3LH, respectively, have high f0 but lower amplitude than the following stressed low tone. Stress-conditioned F0/dB mismatches support the conclusion that high f0/dB attracts pitch accent [Davison (2003)], contrary to the assumption that lexical tone languages such as Chinese do not permit phrasal pitch accents internal to intonational phrases [Ladd (1996)].
Children’s use of prosody to identify ambiguous sets of compound nouns
Authors: Yoshida Michiko , Katz William F.
Published: October 2013

Research has shown that young children can process word duration and fundamental frequency (F0) information in an adultlike manner to disambiguate simple conjoined English phrases [Beach et al., J. Acoust. Soc. Am. 99, 1148–1160 (1996)]. However, the processing of pause duration has not been investigated in this manner. The present study investigates how children use pause duration and F0 to perceive word boundaries, and whether the manner of information processing differs between children and adults. Adults and children (5 and 7 years old) completed a picture-pointing task based on auditory stimuli. Stimuli were computed-edited tokens of the words ‘‘sun,’’ ‘‘flower,’’ and ‘‘pot.’’ From a recording by a male talker, vocoded tokens were created with five steps of pause duration and three steps of fundamental frequency. Both continua ranged between patterns suggesting the interpretations ‘‘sun, flowerpot’’ and ‘‘sunflower, pot.’’ Preliminary results indicate a cue-trading relation between duration and F0 for all listeners, with pause duration playing the dominant role. These data suggest adultlike processing in children as young as 5 years old. Experiments with younger children and a formal evaluation of the pattern recognition processes used by listeners are currently underway in our laboratory.
Noise audit model for acoustic vector sensor arrays on an ocean glider
Authors: Traweek Michael , Polcari John , Trivett David
Published: October 2013

The design of any new sensing array is a complex endeavor, demanding clear understanding of both signal exploitation options and the underlying noise environment (including ambient, structural, flow and electronic components), including cross-channel characteristics. The goal of this effort is to outline an approach for assessing potential advantages of vector sensors to provide ocean gliders with the acoustic sensory input necessary to execute ISR, characterize the environment, and support other mission-enhancing behaviors. At the heart of the approach is development of a noise audit model (NAM) which (coupled with appropriate signal characterizations) enables realistic and comparable evaluation of optimal processing performance for different classes of sensors (e.g., scalar, vector, or tensor). The NAM is a design tool that permits balanced design of the various array components so that the array output is ambient noise limited in the quietest operating environment. Noise components are broken into different source-transmission path chains; correct transfer functions are applied along each path; and sensor/array outputs are then obtained by incoherent sum. Properly structured, rapid evaluation of performance limits can also be supported. The approach will be discussed, and examples of both NAM components and associated performance evaluations will be presented. [Work supported by ONR.]
Multibeam sonar observations of hydrodynamic forcing functions and bubble persistence in a ship wake
Authors: Weber Thomas C. , Lyons Anthony P. , Bradley David L.
Published: October 2013

High frequency (240 kHz) upward-looking multibeam echosounder data were collected from the wake of a twin-screw 50-m research vessel. Volumetric backscatter in each of the 101 1.5×1.5-deg beams was recorded at a repetition rate of approximately 10 s as the ship passed over the moored sonar system. The multibeam sonar’s wide field of view and the low wake drift rate made it possible to image the wake over its entire lifetime of 30 min. The wake quickly separates into distinct port and starboard components. It is suggested that this is caused by vortices shed from the hull that propagate orthogonally to the ship’s direction, entraining bubbles and creating a convergence zone on the outboard side of the vortices as they oppose the buoyant rise of the bubbles. The speed at which the vortices separate is calculated from the data and used in a simple model describing the evolution of the bubbles in the wake. Results show that the hull shedded vortex model is plausible, and that the gas transfer rate from the bubbles must be approximately 25 times less than it would be for surfactant-free bubbles in order to explain the bubble persistence observed in the data.
High-frequency passive sonobuoy designs with PVDF wires and their predicted performance
Authors: Arvelo Juan , Ferat Patrick , Mitnick Ron
Published: October 2013

A novel piezoelectric material technology is used to design high-frequency (>10 kHz) air-deployed sonobuoys that exploit ambient noise anisotropy to enhance their passive performance. High frequencies have the advantages of smaller arrays and reduced clutter from distant shipping noise. PVDF wires are used to design vector sensors in azimuth with vertical directionality. Such hydrophones are used to design vertical and volumetric array configurations. Performance predictions of developed array designs are presented for selected environmental conditions. Results clearly indicate that vertical aperture is necessary to increase array gain against wind-driven noise by exploiting its anisotropy while azimuthal discrimination is required to enhance gain against nearby shipping interference. [This work is sponsored by the Office of Naval Research (ONR).]
Acoustic diffraction by deformed edges of finite length: Theory and experiment
Authors: Stanton Timothy K. , Chu Dezhang
Published: October 2013

The acoustic diffraction by deformed edges of finite length is described analytically and in the frequency domain through use of an approximate line-integral formulation originally applied to deformed finite-length cylinders [T. K. Stanton, J. Acoust. Soc. Am. 86, 691–705 (1989)]. In this case of edges, the factor to the integral specific to the scattering per unit length by the cylinder is replaced by one specific to edge diffraction. The formulation is applied to laboratory data involving elastic disks of finite thickness by incorporating an approximate double-edge diffraction formula for three-sided semi-infinite barriers based on modified solutions of Pierce [A. D. Pierce, J. Acoust. Soc. Am. 55, 941–955 (1974)]. The diffraction in the backscatter direction by individual elastic disks was measured using a variety of disks spanning a range of diameters, thicknesses, and two material properties. A broadband acoustic source was used and the disks rotated over 360° in 1° increments. Given the overlap between some of the different classes of echoes, the analysis was restricted to the leading double-edge echo which was resolved over much of the range of orientation. There was generally good-to-excellent agreement between this approximate formulation and the data over much of the range of frequency and orientation angles. However, the formulation greatly overpredicted the diffraction from the thinnest disks.
Optimization of time-reversal acoustic focusing
Authors: Sutin Alexander , Roides Eric , Sarvazyan Armen
Published: October 2013

Time-reversal acoustic (TRA) focusing systems are typically based on an acoustical resonator (a cavity) in which the multiple reflections of a bouncing acoustic pulse act as a virtual phased array. The efficiency of the TRA focusing system depends on the spectral and temporal parameters of the focused pulse and parameters of the resonator, such as its shape, size, and the relative position of its transducers. The acoustical properties of the resonator material, parameters of the sonicated medium, and the coupling of the TRA resonator and sonicated medium may also affect efficiency. Optimization of such a multiparametric system is a complex problem which is nearly impossible to achieve empirically without an adequate theoretical model. A theoretical model for predicting the efficacy of TRA focusing has been developed and experiments testing theoretical predictions were conducted. The experiments were conducted using a 10-channel TRA system developed in Artann with several broadband resonators in the frequency band of 0.1–2 MHz. The measured dependences of the focused signal on the acoustic pulse spectrum and duration, coupling of the resonator with the sonication medium, and the modes of TRA signal formation (analog or binary) confirmed theoretical predictions. [Work supported by NIH.]
Acoustics of Chinese, Japanese, and Korean bells
Authors: Rossing Thomas D.
Published: October 2013

The earliest known Chinese bells were small clapper bells of clay and copper from the third millennium BC. Beginning with the early Bronze Age (ca. 2000 BC), however, bronze became the material of choice. We discuss early Chinese two-tone bells including nao, yongzhong, niuzhong, and bo and illustrate their vibrational behavior using holographic interferometry. We discuss the effect of various physical parameters on the spacing between the two tones. We compare temple bells from China, Japan, and Korea, including such famous bells as the the Yong-le bell in Beijing and the King Songdok bell in Korea.
Effectiveness of acoustic localization in documenting spatial and temporal patterns in autumn migration of bowhead whales in the Alaskan Beaufort sea
Authors: Blackwell Susanna B. , Norman Robert G. , Greene Charles R. , McLennan Miles W. , McDonald Trent L. , Richardson W. John
Published: October 2013

During September 2001, 2002 and 2003, westbound bowhead whales were localized acoustically using directional autonomous seafloor acoustic recorders (DASARs). Each year, ∼10500–45600 calls were detected over 23–36 days by an array of 11 DASARs deployed 6.5–22 km northeast of the oil-production island Northstar. Locations of origin for the 29% (2001) and 75% (2002) of the calls detected by two or more DASARs were determined by triangulation. Peak call detection rates occurred near 20 September in 2002 and 2003, but early in the month in 2001. In 2003, peak call detection rates exceeded 550 calls/hour. Upsweeps, downsweeps and constant-frequency calls made up 66%–68% of the calls each year. The migration corridor was similar in 2001 and 2002, but closer to shore by ∼10 km in 2003. Comparisons with yearly aerial censuses by the Minerals Management Service showed that the two methods both documented migration timing and the offshore distance of the migration corridor. Aerial surveys covered a larger area and continued after onset of freeze-up. The acoustic method revealed more temporal and spatial details because it operated continuously over long periods independent of weather and darkness, and provided far more detections of whales. [Work supported by BP.]
Prediction of sound transmission loss of honeycomb sandwich panel by higher order approach
Authors: Wang Tongan , Rajaram Shankar , Nutt Steven R.
Published: October 2013

People have studied the sound transmission loss (STL) of sandwich panels since the 1970s. However, most of the existing prediction methods have been based on single-layer dynamical models, neglecting the symmetric (dilatational) movements of the skins. Consequently, the symmetric coincident frequency of the sandwich panel cannot be predicted using those approaches. To account for this dilatational motion of the sandwich structures, different methods were utilized. However, most of them were based on one dimensional sandwich beams theories. The authors have also applied the consistent higher order beam approach to calculate the sound transmission loss of a unidirectional sandwich panel. Although the one dimensional approximation is good in predicting STL, the effects of some factors, such as the anisotropy and orientation of the principle axis of the panel, cannot be estimated. In the current work, the authors extended that one dimensional beam model into two dimensions, which allows us to calculate the STL of sandwich plates with composite laminate face sheets and honeycomb core. Both flexural (antisymmetric) and dilatational (symmetric) motions of the sandwich panel were considered in the study. The predictions were finally compared with our experimental data.
Detection enhancement using multiple time-reversed guide sources in shallow water
Authors: Calvo David C. , Gaumond Charles F. , Fromm David M. , Lingevitch Joseph F. , Menis Richard , Kim Ellis , Edelmann Geoffrey F.
Published: October 2013

Detection in a monostatic, broadband, active sonar system in shallow water is degraded by propagation-induced spreading. Improved detection has previously been achieved in the 3- to 3.5-kHz range by using the information in time-reversed one-way transmissions from multiple spatially separated guide sources. Detection results in the wider 500- to 3500-Hz band from an experiment south of the Hudson Canyon off the coast of New Jersey are presented in this talk. The target as well as the guide source was an echo repeater positioned at various water depths and ranges. Various subapertures of the 64-element NRL source receiver array were used to transmit 0.25-s LFMs and detect their echoes. The guide source data is analyzed to show the amount of information content depending on aperture and bandwidth. The improvement in probability of detection using multiple guide-source signals is compared with a baseline probability using matched filtering. Improvement in detection as a function of the number of guide sources and their range is also discussed. [Work supported by ONR.]
Raytubes in an ocean acoustic environment
Authors: Dzieciuch Matthew , Cornuelle Bruce
Published: October 2013

In ocean acoustic tomography, sound propagation is typically modeled by ray propagation, which allows an easy answer to the question, ‘‘Where does the sound go?’’ Sound obeys the wave equation and ray propagation is only valid in the high frequency limit. It is still possible to answer the question by generating a raytube using the method outlined by Bowlin [J. Acoust. Soc. Am. 89, 2663–2669 (1991)] for environments where full wave modeling is appropriate. It is thus possible to ask how the width of the raytube changes with frequency, bandwidth, and range. Perhaps more importantly, from an acoustical oceanography point of view, how does the environment impact the width? We investigate the effects of the strength of the internal wave field, the depth of the mixed layer, and the presence of ocean spiciness on the raytube width.
Fundamental frequency and the intelligibility of competing sentences with cochlear implant processing
Authors: Stickney Ginger S. , Chang Janice , Assmann Peter F. , Zeng Fan-Gang
Published: October 2013

Speech perception in the presence of another competing voice is one of the most challenging tasks for cochlear implant users. Several studies have shown (1) that the fundamental frequency (F0) is a useful cue for segregating competing speech sounds and (2) the F0 is better represented by the temporal fine structure than the temporal envelope. However, current cochlear implant speech processing algorithms emphasize the temporal envelope information and discard the temporal fine structure. In this study, speech recognition was measured as a function of the F0 separation of the target and competing sentence in normal-hearing and cochlear implant listeners. For the normal-hearing listeners, the combined sentences were processed through either a traditional cochlear implant simulation or a new algorithm which additionally extracts a slowed-down version of the temporal fine structure. The results showed no benefit of increasing F0 separation for the cochlear implant or traditional simulation groups. However, as found with unprocessed sentences presented to normal-hearing listeners, the new algorithm resulted in gradual improvements with increasing F0 separations. These results demonstrate that inadequate coding of the temporal fine structure in current speech processing algorithms may complicate the segregation of competing speech sounds. [Work supported by NIDCD F32DC05900 and R01DC02267.]
Perceptual shift of the /d/-/t/ voice onset time boundary following exposure to French-accented English
Authors: Clarke Constance M. , Luce Paul A.
Published: October 2013

Previous work suggests native English listeners perceptually adapt to foreign-accented English, as indicated by faster reaction times, after only brief exposure [C. M. Clarke, Proc. ICSLP, 253–256 (2002)]. The present study explored whether changes in the perceptual criteria for phonetic categories may contribute to this increased processing speed. Categorization of /d/ and /t/ was tested using a voice onset time (VOT) continuum. French-accented English was used as the exposure accent because it typically contains prevoiced /d/’s and short-lag /t/’s. Native English has short-lag /d/’s and long-lag /t/’s. Categorization was tested prior to exposure and again following 20, 40, and 60 accented sentences. Each set of 20 sentences contained 20 syllable-initial /t/’s and /d/’s. It was predicted that native English listeners categorization boundaries would shift to lower VOTs after exposure to French-accented speech. Native English speech was used in a control condition. To test the contribution of exposure to specific exemplars of /d/ and /t/ versus exposure to more general characteristics of an accent, two other conditions were included: native English speech with /d/’s and /t/’s digitally modified to be French-like, and French-accented speech with /d/’s and /t/’s digitally modified to be English-like. [Work supported by NIH.]
Impedance tube characterization of a novel low frequency acoustic barrier
Authors: Henderson B. Kyle , Franke Scott E.
Published: October 2013

The launch acoustic environment impinging on space payloads during ascent can be damaging to sensitive critical spacecraft components. Conventional foam acoustic mitigation for payload fairings tends to be ineffective at low frequencies due to volume and weight constraints. Acoustic barriers may be employed to increase transmission loss at lower frequencies through the use of a heavy septum layer within the foam, but with the concomitant disadvantage of added weight, which reduces payload capacity. A lightweight barrier is presented employing a thin metal foil bonded to a foam layer with spherical masses embedded in the foil in a periodic array. It is theorized that the particles enable the excitation of bending waves in the plane of the foil, causing inter-particle interactions over a frequency range influenced by the foil material properties, thickness, and particle spacing which increase the reflection coefficient of the layer. The transmission loss and absorption spectra are measured using the ASTM C384 standard. The results should allow for optimization of foil-foam performance with respect to geometric and material variables. It is expected that these foil barriers might provide protection over low frequency bandwidths identified by analysis as harmful to a payload.
Attenuation of blast sound by a mixed stand of pine and hardwood
Authors: White Michael J. , Pater Larry L. , Lee Ryan J. , Swenson George W.
Published: October 2013

We performed an experiment to determine the attenuation of impulsive sound by a forest in northeastern Texas in July 2002. In the measurement, microphones were placed along a line that extended at one end into approximately 300 m of mostly 20-cm-diam pine trees, and at the other end into an open field of roughly the same extent. Explosive charges of 0.57- and 2.27-kg Composition C-4 were detonated at four locations along the line, at either edge of the open field and at either edge of the trees, in order to compare sound attenuation rates within the woods to those in the open field. Additional microphones were placed 2 and 4 km away to compare propagation from sources in either wooded or open positions to microphones in either wooded or open positions, with all paths substantially forested. Charge size, height-of-burst, and microphone height were varied in order to excite and probe a variety of acoustic propagation modes within the tree layer. We discuss preliminary results of 1/3-octave band analysis of this data set, consider ways to separately identify the observed power law and exponential decay rates, and speculate on their controlling mechanisms.
Noise control for a ChamberCore cylindrical structure using long T-shaped acoustic resonators
Authors: Li Deyu , Vipperman Jeffrey S.
Published: October 2013

The Air Force Research Laboratory, Space Vehicles Directorate has developed a new advanced composite launch vehicle fairing (referred to as ‘‘ChamberCore’’). The ChamberCore is sandwich-type structure fabricated from multi-layered composite face sheets separated by channels that form passive acoustic chambers. These acoustic chambers have a potential to create an acoustic resonator network that can be used to attenuate noise inside the closed ChamberCore cylindrical structure. In this study, first, the feasibility of using cylindrical Helmholtz resonators to control noise in a mock-scale ChamberCore composite cylinder is investigated. The targeted frequencies for noise control are the first four acoustic cavity resonances of the ChamberCore cylinder. The optimal position of the Helmholtz resonators for controlling each targeted cavity mode is discussed, and the effects of resonator spacing on noise attenuation are also experimentally evaluated. Next, six long T-shaped acoustic resonators are designed and constructed within the acoustic chambers of the structure and investigated. Several tests are conducted to evaluate the noise control ability of the resonators in the ChamberCore cylinder. Reductions ranging from 3.2 to 6.0 dB were observed in the overall mean-square noise reduction spectrum at the targeted inner cavity resonance frequencies. [Work supported by AFRL/DV.]
Children’s discrimination of vowel sequences
Authors: Coady Jeffry A. , Kluender Keith R. , Evans Julia
Published: October 2013

Children’s ability to discriminate sequences of steady-state vowels was investigated. Vowels (as in ‘‘beet,’’ ‘‘bat,’’ ‘‘bought,’’ and ‘‘boot’’) were synthesized at durations of 40, 80, 160, 320, 640, and 1280 ms. Four different vowel sequences were created by concatenating different orders of vowels for each duration, separated by 10-ms intervening silence. Thus, sequences differed in vowel order and duration (rate). Sequences were 12 s in duration, with amplitude ramped linearly over the first and last 2 s. Sequence pairs included both same (identical sequences) and different trials (sequences with vowels in different orders). Sequences with vowel of equal duration were presented on individual trials. Children aged 7;0 to 10;6 listened to pairs of sequences (with 100 ms between sequences) and responded whether sequences sounded the same or different. Results indicate that children are best able to discriminate sequences of intermediate-duration vowels, typical of conversational speaking rate. Children were less accurate with both shorter and longer vowels. Results are discussed in terms of auditory processing (shortest vowels) and memory (longest vowels). [Research supported by NIDCD DC-05263, DC-04072, and DC-005650.]
Acoustics of automotive catalytic converter assemblies
Authors: Dickey Nolan S. , Selamet Ahmet , Parks Steve J. , Tallio Kevin V. , Miazgowicz Keith D. , Radavich Paul M.
Published: October 2013

In an automotive exhaust system, the purpose of the catalytic converter is to reduce pollutant emissions. However, catalytic converters also affect the engine and exhaust system breathing characteristics; they increase backpressure, affect exhaust system acoustic characteristics, and contribute to exhaust manifold tuning. Thus, radiated sound models should include catalytic converters since they can affect both the source characteristics and the exhaust system acoustic behavior. A typical catalytic converter assembly employs a ceramic substrate to carry the catalytically active noble metals. The substrate has numerous parallel tubes and is mounted in a housing with swelling mat or wire mesh around its periphery. Seals at the ends of the substrate can be used to help force flow through the substrate and/or protect the mat material. Typically, catalytic converter studies only consider sound propagation in the small capillary tubes of the substrate. Investigations of the acoustic characteristics of entire catalytic converter assemblies (housing, substrate, seals, and mat) do not appear to be available. This work experimentally investigates the acoustic behavior of catalytic converter assemblies and the contributions of the separate components to sound attenuation. Experimental findings are interpreted with respect to available techniques for modeling sound propagation in ceramic substrates.
Propagation of uncertainty for acoustic fields using polynomial chaos expansions
Authors: Finette Steven
Published: October 2013

The concept of uncertainty is related to both reducible and irreducible errors that can enter a computer simulation through several channels: modeling errors, discretization of the continuous dynamical system, missing knowledge/information concerning boundary and initial conditions, and selection of parameter values. In ocean waveguide modeling, uncertainty inherent in the lack of knowledge of the sound speed distribution, for example, is mapped into the acoustic field. In a sense, it propagates along with the acoustic field to which it is coupled, though the computed pressure field at a point in the waveguide does not normally include an explicit measure of this uncertainty. This presentation will describe a method for explicitly incorporating uncertainty into the dynamics for acoustic wave propagation in ocean waveguides. In order to quantify uncertainty in numerical simulations for underwater acoustics problems, the application of stochastic basis expansions of random processes that effectively map uncertainty in the parameter input space to uncertainty in the system output space is considered. The relationship to Monte Carlo methods is also discussed. [Work supported by ONR.]
The effects of auditory and visual vowel training on speech reading performance
Authors: Richie Carolyn , Kewley-Port Diane
Published: October 2013

Speech reading, the use of visual cues to understand speech, may provide a substantial benefit for normal-hearing listeners in noisy environments and for hearing-impaired listeners in everyday communication. However, there exists great individual variability in speech reading ability, and studies have shown that only a modest improvement in speech reading ability is achieved with training. The purpose of this investigation was to determine the effects of a novel approach to speech reading training on word and sentence identification tasks. In contrast to previous research, which involved training on consonant recognition, this study focused on vowels. Two groups of normal-hearing adults participated in auditory–visual (AV) conditions with added background noise. The first group of listeners received training on the recognition of 14 English vowels in isolated words, while the second group of listeners received no training. All listeners performed speech reading pre- and post-tests, on words and sentences. Results are discussed in terms of differences between groups, dependent upon whether training was administered, and a comparison is made between this and other speech reading training methods. Finally, the potential benefit of this vowel-based speech reading training method for the rehabilitation for hearing-impaired listeners is discussed. [Work supported by NIHDCD-02229.]
Helmholtz equation least squares method for transient nearfield acoustic holography
Authors: Lu Huancai , Wu Sean
Published: October 2013

The generalized Helmholtz equation least squares (HELS) formulations for reconstructing transient acoustic radiation from an arbitrary object subject to an arbitrary time-dependent excitation are derived. To facilitate the derivations, the Laplace transform is employed and the vibro-acoustic quantities on the source surface are solved explicitly in terms of the acoustic pressures measured on a conformal surface around the source at close range multiplied by transfer functions in the Laplace domain first. The vibro-acoustic responses in the time domain can then be expressed as convolution integrals of the measured acoustic pressure signals over temporal kernels. Replacing the spherical Hankel functions in the transfer functions with polynomial expressions, we can recast the infinite integrals in the inverse Laplace transform as contour integrals and evaluate the temporal kernels by using residue theorem. Once the temporal kernels are determined, the vibro-acoustic quantities anywhere in the field, including those on the source surface can be reconstructed directly. Numerical examples of reconstruction of transient acoustic radiation from a baffled disk subject to impulsive and arbitrarily time-dependent excitations are demonstrated. [Work supported by NSF.]
A nonlinear cochlear model with the outer hair cell piezoelectric activity
Authors: Jiang Xiaoai , Grosh Karl
Published: October 2013

In this paper we present a simple cochlear model which captures the most important aspect of nonlinearity in the cochlea—the nonlinearity caused by the piezoelectric-like activity of outer hair cells and the variable conductance of the outer hair cell stereocilia. A one-dimensional long-wave model is built to simulate the dynamic response of the fluid-loaded basilar membrane. The basilar membrane is simulated as isolated linear oscillators along the cochlear length, and its motion is coupled with the fluid pressure and the nonlinear force produced by the outer hair cells. As the basilar membrane moves, the fluid shears stereocilia, and the resulting ion flow changes the transmembrane potential of the outer hair cells and subsequently their length, leading to further movement of the basilar membrane. The piezoelectric-like activity of the outer hair cell is simulated by a current source, and stereocilia motion is modeled as a varying conductance that changes as the basilar membrane moves. A solution in the time domain will be presented. [Work supported by NIH.]
Transfer of oceanographic and bottom variability into shallow water propagation and reverberation uncertainty
Authors: LePage Kevin D. , Holland Charles W. , Goff John A.
Published: October 2013

Often an oceanographic or geoacoustic description of a particular environment is not available on a fine enough scale to capture all the variability that is known to exist at the site. However in cases where resources are available to characterize a particular piece of the environment at the scales of acoustic importance, these measurements may be used to predict the uncertainty of propagation and reverberation in nearby regions as long as the bottom and oceanographic processes are homogeneous over the length scale covering the two sites. In these cases stochastic treatments of the environmental variability at fine scales may be employed and a resulting uncertainty on acoustic propagation and reverberation predicted. Here the uncertainty of acoustic propagation and reverberation due to fine scale sound speed profile variability associated with internal waves and seafloor heterogeneity is evaluated using Monte-Carlo techniques. Results show that for the New Jersey and Eel river STRATAFORM sites seafloor variability leads to predictions of reverberation uncertainty of less than 1 dB at 4 kHz, while oceanographic variability due to internal waves is predicted to cause about 2 dB of uncertainty in the same frequency regime. [Work supported by ONR Capturing Uncertainty DRI.]
Scattering calculations for a sphere ensonified by a fully depth sampling TRM in a shallow water waveguide
Authors: LePage Kevin D. , McDonald B. Edward
Published: October 2013

One potential application of a Time Reversal Mirror (TRM) is as an acoustic tripwire [Kuperman et al., IEEE J. Oceanic Eng (submitted)] where the focus of the TRM at the probe source range and depth is degraded by the presence of an object in the waveguide. Here an efficient technique for approximating the time domain scattered field of a rigid or elastic sphere in a shallow water waveguide is presented based on the Ingenito model [J. Acoust. Soc. Am. 82, 2051–2059 (1987)], a WKB decomposition of normal modes into up- and down-going plane waves at the scatterer depth, and the narrowband approximation for the time domain signal broadcast from a fully depth sampling TRM. Results show that the degradation of the TRM focusing near the focal region is as expected a strong function of the scatter size and frequency, as well as the usual parameter of the critical angle in the bottom. Calculations in the nearfield of the scatterer show shadowing for spheres above ka=1 of all the pseudo plane wave components of the TRM field, which yields an interesting evolution of the forward scattered field as a function of time, angle, and scatterer depth. [Work supported by ONR.]
Measurement uncertainty of seabed reflectivity
Authors: Holland Charles
Published: October 2013

The seabed reflection coefficient is a fundamental property of the ocean waveguide. Measurements of the frequency and angular dependence of the reflection coefficient can provide information about the geoacoustic properties of the seabed or can be used as an input to propagation models. The uncertainty of the measurements must be known in order to determine the prediction uncertainties for the acoustic field and/or the geoacoustic properties. An analysis indicates that reflection measurements [Holland and Osler, J. Acoust. Soc. Am. 107, 1263–1279 (2000)] have a standard deviation from 0.5–1 dB at full angular resolution depending on frequency and experiment geometry. The dominant contribution to the error is source amplitude variability and a new processing approach was developed that reduces the error for frequencies above a few hundred Hz. A further reduction in the uncertainty can be obtained by averaging in angle, for example, a 1 angle averaging leads to a standard deviation of 0.1–0.5 dB. Errors in the angle estimate are a few tenths of a degree from 0–34° grazing angle: the crucial angular range for predicting long-range propagation or for geoacoustic property inversion. [Research sponsored by ONR.]
Various applications of Active Field Control (AFC)
Authors: Watanabe Takayuki , Miyazaki Hideo , Kishinaga Shinji , Kawakami Fukushi
Published: October 2013

AFC is an electro-acoustic enhancement system, which has been under development at Yamaha Corporation. In this paper, several types of various AFC applications are discussed, while referring to representative projects for each application in Japan. (1) Realization of acoustics in a huge hall to classical music program, e.g., Tokyo International Forum. This venue is a multipurpose hall with approximately 5000 seats. AFC achieves loudness and reverberance equivalent to those of a hall with 2500 seats or fewer. (2) Optimization of acoustics for a variety of programs, e.g., Arkas Sasebo. AFC is used to create the optimum acoustics for each program, such as reverberance for classical concerts, acoustical support for opera singers, uniformity throughout the hall from the stage to under-balcony area, etc. (3) Control of room shape acoustical effect, e.g., Osaka Central Public Hall: In this renovation project, preservation of historically important architecture in the original form is required. AFC is installed to vary only the acoustical environment without architectural changes. (4) Assistance with crowd enthusiasm for sports entertainment, e.g., Tokyo Metropolitan Gymnasium. In this venue, which is designed as a very absorptive space for speech intelligibility, AFC is installed to enhance the atmosphere of live sports entertainment.
The importance of angle of incidence on acoustic to seismic coupling
Authors: Howard Wheeler B. , Hickey Craig J. , Sabatier James M.
Published: October 2013

Acoustic to seismic coupling has been successfully used in the detection of buried mines and more recently in the investigation of sub-surface soil structure. Due to the downward refracting nature of the acoustic wave at the air–earth interface, the mechanism by which airborne waves couple to the earth is thought to be insensitive to changing angles of incidence. In experimental setups, the airborne sound sources have been positioned at angles ranging from normal to grazing with respect to the ground surface. A more controlled study of the importance of angle of incidence has been performed. Data from field experiments will be presented illustrating the importance of angle of incidence on acoustic to seismic coupling.
Olfactory Neurons Get Stressed Out
Authors: Berndt Jason D.
Published: October 2013

Olfactory receptors self-select by inducing the unfolded protein response.
Ganciclovir-Resistant Cytomegalovirus Infections among Lung Transplant Recipients Are Associated with Poor Outcomes despite Treatment with Foscarnet-Containing Regimens
Authors: Minces Lucio R. , Nguyen M. Hong , Mitsani Dimitra , Shields Ryan K. , Kwak Eun J. , Silveira Fernanda P. , Abdel-Massih Rima , Pilewski Joseph M. , Crespo Maria M. , Bermudez Christian , Bhama Jay K. , Toyoda Yoshiya , Clancy Cornelius J.
Published: October 2013

Ganciclovir-resistant cytomegalovirus (CMV) infections are reported infrequently among lung transplant recipients receiving extended valganciclovir prophylaxis. We performed a single-center, retrospective review of ganciclovir-resistant CMV infections in a program that employed valganciclovir prophylaxis for ≥6 months after lung transplant. CMV infections were diagnosed in 28% (170/607) of patients. UL97 mutations were detected in 9.4% (16/170) of CMV-infected patients at a median of 8.5 months posttransplant (range, 5 to 21) and despite prophylaxis for a median of 7 months (range, 4 to 21). UL97 mutations were canonical; 25% (4/16) of strains carried concurrent UL54 mutations. Ganciclovir-resistant CMV was more likely with breakthrough infections (75% [12/16] versus 19% [30/154];
P
= 0.00001) and donor positive/recipient negative (D+/R−) serostatus (75% versus 45% [69/154];
P
= 0.03). The median whole-blood CMV load was 4.13 log
10
copies/cm
3
(range, 2.54 to 5.53), and 93% (14/15) of patients had low-moderate immune responses (Cylex Immunoknow). Antiviral therapy was successful, failed, or eradicated viremia followed by relapse in 12% (2/16), 31% (5/16), and 56% (9/16) of patients, respectively. Eighty-seven percent (14/16) of patients were treated with foscarnet-containing regimens; toxicity developed in 78% (11/14) of these. Median viral load half-life and time to viremia eradication among foscarnet-treated patients were 2.6 and 23 days, respectively, and did not correlate with protection from relapse. Sixty-nine percent (11/16) of patients developed CMV pneumonitis, and 25% (4/16) died of it. Serum viral load was independently associated with death among foscarnet-treated patients (
P
= 0.04). In conclusion, ganciclovir-resistant CMV infections remained a major cause of morbidity and mortality following lung transplantation. Foscarnet-based regimens often eradicated viremia rapidly but were ineffective in the long term and limited by toxicity.
β-Lactams Enhance Vancomycin Activity against Methicillin-Resistant Staphylococcus aureus Bacteremia Compared to Vancomycin Alone
Authors: Dilworth Thomas J. , Ibrahim Omar , Hall Pamela , Sliwinski Jora , Walraven Carla , Mercier Renée-Claude
Published: October 2013

Vancomycin (VAN) is often used to treat methicillin-resistant
Staphylococcus aureus
(MRSA) bacteremia despite a high incidence of microbiological failure. Recent
in vitro
analyses of β-lactams in combination with VAN demonstrated synergistic activity against MRSA. The goal of this study was to examine the impact of combination therapy with VAN and a β-lactam (Combo) on the microbiological eradication of MRSA bacteremia compared to VAN alone. This was a retrospective cohort study of patients with MRSA bacteremia who received Combo therapy or VAN alone. Microbiological eradication of MRSA, defined as a negative blood culture obtained after initiation of therapy, was used to evaluate the efficacy of each regimen. A total of 80 patients were included: 50 patients in the Combo group and 30 patients in the VAN-alone group. Microbiological eradication was achieved in 48 patients (96%) in the Combo group compared to 24 patients (80%) in the VAN-alone group (
P
= 0.021). In a multivariable model, the Combo treatment had a higher likelihood of achieving microbiological eradication (adjusted odds ratio, 11.24; 95% confidence interval, 1.7 to 144.3;
P
= 0.01). In patients with infective endocarditis (
n
= 22), 11/11 (100%) who received Combo therapy achieved microbiological eradication compared to 9/11 (81.8%) treated with VAN alone, but the difference was not statistically significant (
P
= 0.20). Patients with MRSA bacteremia who received Combo therapy were more likely to experience microbiological eradication of MRSA than patients who received VAN alone.