bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis and comparison of spatial correlation and intensity distribution statistics
Authors: Smith Chad M. , Brown Daniel C.
Published: November 2017

Active sonar processing systems operating in shallow-water littoral environments are often plagued with excessive false alarms, generally referred to as sonar clutter. At times the effects of these clutter events can be mitigated through repeated measurements and/or careful sonar operator examination; however, this process can be time consuming and even experienced sonar operators may have difficulty identifying targets in cluttered environments. Additionally, increasing interest in autonomous vehicle platforms and the push for real-time decision and performance management introduces further requirements on sonar systems. This work provides an empirical analysis of the potential in using spatial correlation of the backscattered wavefront as a classification metric, and compares this metric to a commonly used probability density function (PDF) processing method. The shape of the PDF of the backscattered acoustic intensity is often used in sonar processing systems such as constant false alarm rate (CFAR) detectors. These PDFs generally provide an estimate of the Rayleigh-like (random phase scattering) or non-Rayleigh-like (generally finite bright scatterers) nature of temporal variations in acoustic returns. This talk will outline information that may be available about clutter events based on measurements of spatial correlation. [Work supported by Office of Naval Research.]
Sensitivity of acoustic propagation modeling to variations in ocean environmental conditions
Authors: Margolina Tetyana , Joseph John E. , Jordan Mary
Published: November 2017

A parabolic equation acoustic model has been used to estimate transmission loss for a mid-frequency sound source to assist in marine mammal behavioral response studies. The sound propagation is modeled for a range-dependent environment using the Navy Digital Bathymetric Data Base and Bottom Sediment Type database, NOAA Global Ocean Sediment Thickness Dataset, and the High-Resolution Global Sea Surface Wind Speed monthly climatology. The sound speed along the propagation path is modeled using two ocean temperature/salinity fields of different spatial and temporal resolution: monthly 0.25 deg outputs of the Generalized Digital Environmental Model (GDEM), and the daily 1/12 deg outputs of the regional Hybrid Coordinate Ocean Model (HYCOM). The modeling was done for two operational areas with strikingly different ocean environments, the Southern California Bight and the Gulf Stream region off Cape Hatteras. The latter represents a much more dynamic ocean environment with profound temperature fronts, highly variable meso- and submesoscale eddy activity, and sharp bathymetry gradients along the shelf break. Received sound levels measured on tagged marine mammals, and synchronized sound source/sound receiver tracklines are used to estimate uncertainty of the acoustic modeling results, and the non-linear sensitivity of the model to wide-range variations in the ocean environmental conditions.
Geoacoustic sediment model discrimination using acoustic color comparison
Authors: Bonomo Anthony L. , Isakson Marcia J.
Published: November 2017

Many competing geoacoustic models exist to represent sandy sediments. These models can be fluid, elastic, or poroelastic, depending on the number and types of waves the sediment is assumed to support. In this talk, a fully scattered field finite element approach is utilized to construct acoustic color templates for a buried spherical aluminum shell and a spherical bubble. The simulated results are then used to assess the ability of target strength measurements to discriminate between the predictions of the competing sediment models. Such discrimination may help determine the physical validity of a given geoacoustic model and aid in model selection. Five geoacoustic sediment models are considered: a simple fluid, constant-Q fluid model, the effective density fluid model of Williams, the viscous grain shearing model of Buckingham, the Biot-Stoll poroelastic model, and the extended Biot model of Chotiros. [Work supported by ONR, Ocean Acoustics.]
Design of halls for the enjoyment of American music
Authors: Talaske Richard
Published: November 2017

Designing for contemporary music performance is more involved than achieving the accepted mid-frequency reverberation time within the performance space. While accomplishing the correct degree of reverberance is essential, this alone is not a sufficient condition for creating an acoustic environment suitable for the enjoyment of jazz, blues, folk, rock, computer, world, or other non-symphonic or non-choral genres of music. Control of low-pitched sound, achieving moderate running liveliness, and creating a microphone-friendly acoustic environment are also essential design goals. As usual, the acoustic goals should be accomplished while developing a welcoming room design which offers intimacy between performers and patrons and a communal audience setting. These acoustical and societal goals are discussed in relation to completed projects such as the Ellis Marsalis Center for Music in NOLA, The Sidney Harman Center in DC, and the Old Town School of Folk Music in Chicago.
Echolocation for restoration: Odontocete monitoring in the Gulf of Mexico
Authors: Frasier Kaitlin E. , Cohen Rebecca , Trickey Jennifer S. , Wiggins Sean M. , Solsona Berga Alba , Soldevilla Melissa , Garrison Lance , Baumann-Pickering Simone , Hildebrand John
Published: November 2017

In the late 1990s, George E. Ioup began studying echolocation clicks as a means of understanding marine mammals in the Gulf of Mexico (GOM). He also led one of the few research programs focused on pelagic species in this chronically impacted region in the years preceding the Deepwater Horizon oil spill. Today, passive acoustic monitoring (PAM) is one of the primary tools used to study the nearly 20 pelagic odontocete species found in the GOM, including sperm whales, beaked whales, dolphins, and Kogia species. Since 2010, PAM devices have been deployed nearly continuously in the region, driven by an urgent need to understand the long-term effects of both acute and chronic anthropogenic impacts on GOM marine mammal populations. Recent advances fueled by robust, reliable PAM technologies include the development of multi-year timeseries documenting changes in species densities across continental shelf and slope habitats, differentiating GOM odontocete species based on echolocation click properties, and leveraging long-term datasets to understand the influence of habitat variability on offshore species distributions. These capabilities are proving PAM is indispensable as an observation method for damage assessment, decision support, and restoration activities for marine mammals, especially inaccessible pelagic populations.
In memory of George E. Ioup: Founder of the University of New Orleans physics program at the Stennis Space Center
Authors: Chin-Bing Stanley A. , Ioup Juliette W.
Published: November 2017

In the late 1970s, two U.S. Navy organizations were formed and located in an area now known as the Stennis Space Center, Mississippi, located nearly 50 miles East of the University of New Orleans (UNO). These two organizations employed nearly 1500 scientists and technicians who needed advanced training in physics, specifically courses involving acoustics and signal processing. In 1982, Professor George E. Ioup took the initiative to have UNO develop and teach these courses on-site at the Stennis Space Center. In the following 33 years, nearly 20 different graduate level courses were developed and taught multiple times at the Stennis Space Center. It was possible to take all the necessary courses needed for the Masters and Ph.D. degrees on-site, while maintaining full-time employment. Under Professor Ioup's leadership, several dozen Navy scientists received advanced degrees from the University of New Orleans, and many more received specific training that enhanced their professional careers. This presentation will highlight the dedicated efforts and successes of George Ioup in creating the UNO physics program at the Stennis Space Center, MS.
Acoustic propagation in a fractal network of scatterers
Authors: Gibiat Vincent , Bertaud Etienne , PONGE MArie-Fraise , Jacob Xavier
Published: November 2017

Fractal networks, built on Cantor set, Fibonacci series or Sierpinsky sets are characteristics of a structural organization between periodic and random. On the other hand, they have been proved to be a good descriptor of irregular systems as the well known description of Brittany coasts. Such systems can be seen as irregular boundaries, as in the case of irregular coasts, while the wave equations are still usable inside theses boundaries. Along the boundaries, wave localization is possible. Another case is that where boundaries are regular while the organization of the material where waves are propagating carries the fractality. Wave propagation on such systems can be considered through the aspect of multiple scattering, and on 1D systems as well on 2D systems built on Cantor or sierpinski set, it is possible to show the existence of localized modes. On the contrary to the previous case, localization arises not along the boundaries but inside the propagating medium. Less common organization of scatterers, for instance, those built on Fibonacci series can also be compared to periodic organizations as well as random ones. Various examples will be shown on experimental material as on theoretical or numerical examples.
Relationship between ultrasound scattering and acoustic impedance maps in sparse and dense random media
Authors: Mamou Jonathan , Tamura Kazuki , Rohrbach Daniel , Yamaguchi Tadashi , Franceschini Emilie
Published: November 2017

Quantitative modeling of ultrasound scattering from soft tissues has been used extensively to characterize soft tissues. In this approach, tissues are typically modeled as a random medium containing scatterers of specific shapes, acoustic properties, and spatial arrangements. Under plane-wave insonification and assuming weak scattering (i.e., Born approximation), the backscattered coefficient (BSC) of such a random medium is fully described by the power spectrum of its three-dimensional (3D) impedance map (ZM). A two-dimensional (2D) ZM can be obtained by scanning acoustic microscopy (SAM) applied to thin tissue sections using very high-frequency ultrasound (>100 MHz). Under isotropic assumptions, 2DZMs can predict the BSC accurately; nevertheless, in the case of dense media, where the locations of the scatterers can be correlated, some of the theoretical assumptions fail, which requires introduction of the structure-factor model (SFM). Using experimental and simulated data, this presentation will review computation of the BSC from ultrasound measurements, the working principles of SAM, the use of 3DZMs and 2DZMs to predict the BSC, SFM estimation from 2DZMs and 3DZMs, and the use of SFM for BSC computation and tissue characterization.
Thermophones for sonar applications
Authors: Mayo Nathanael K. , Schumacher Christian , Cox Donald , Boisvert Jeffrey E. , Blottman John B. , Howarth Thomas R.
Published: November 2017

Thermophones are electrically driven thermoacoustic sound projectors which have historically been used as a primary source of sound. Thermophones have a sound spectra that are largely determined by their housing and support and efficiencies that are determined by the device’s ability to maintain a dynamic temperature gradient across a gaseous layer surrounding the thin heating element. A number of factors make thermophones an attractive technology for underwater use including the relative ease and low cost of production, the large thermal reservoir provided by the surrounding aquatic environment, and the ability to tune the spectra over a broad range of frequencies. We present calibrated acoustic underwater tests performed on thermophones which demonstrate the potential for a new class of sonar transducers. Small, 6.35 cm diameter, inert gas filled laminate pouch thermophones were fabricated which provide a low frequency resonance. Additionally, a liquid filled thermophone demonstrates a smooth response over a wide frequency band.
Cylindrical heat conduction models for enclosed thermophones
Authors: Dzikowicz Benjamin , Tressler James , Baldwin Jeffery W.
Published: November 2017

The efficiency of enclosed thermophones is governed by the time-dependent heat transport between the heating element and the enclosure gas. Efficiency gains have been made by reducing the heat capacitance of the heating elements so that a maximum amount of energy is available for transport. However, efficiency is still limited when there is poor conduction into and out of the enclosure gas. An analytical model for the conduction in an enclosed thermophone with a heating element composed of a regularly spaced linear array of conducting fibers will be presented. The model considers interaction between the individual fibers and treats the enclosure wall as a heat sink. The conduction model will be incorporated into a device model which can calculate steady-state acoustic output. The results are compared against experimental data. In addition, the device model can be used to explore the optimal fiber spacing for enclosed thermophones with regularly spaced linear array heating elements. [Work funded by the Naval Research Laboratory.]
Modeling nonlinear acoustic landmine detection using a soil plate oscillator apparatus
Authors: Santos Emily V. , Korman Murray S.
Published: November 2017

In modeling nonlinear acoustic landmine detection, there will be a cylindrical drum-like buried target. This target, which has a clamped thin elastic plate, rigid sidewalls, and bottom plate, is buried in an open concrete “soil tank” containing dry sifted masonry sand. Subwoofers located 40 cm above the surface are driven with a swept tone from 50 to 450 Hz to generate airborne sound that couples into the sand exciting vibration in the buried target. A small geophone is used to measure the “ground” vibration profile across the buried target. Nonlinear tuning curves of vibration particle velocity vs. frequency are used to compare “over—off the target” results. The backbone curves (peak velocity vs. corresponding resonant frequency) are different in these cases—such that resonances due to soil alone or soil over a compliant buried target can be distinguished. Next, a soil plate oscillator SPO (consisting of two circular flanges sandwiching and clamping a thin circular elastic plate that supports a cylindrical level column of sand above the plate) is driven by airborne sound. Nonlinear tuning curve vibration at points across the sand are compared with the results in the “idealized” landmine detection experiment to develop a lumped element model of the system.
Searching for early reflected waves after strike of Caribbean steelpan using time-resolved electronic speckle pattern interferometry
Authors: Morrison Andrew C. , Moore Thomas , Zietlow Daniel
Published: November 2017

Electronic speckle-pattern interferometry has become a popular tool for studying the operating deflection shapes and normal modes of musical instruments. Normally, ESPI is used with cameras having frame rates below 50 Hz, and the resulting interferograms are the result of a time average over many oscillations. Using ESPI with a high speed camera operating at frame rates of several thousand frames per second allows for time-resolved examinations of transient motion, and this technique has been used to study the motion immediately following the strike on a Caribbean steelpan. Caribbean steelpans are a complex system of coupled oscillators and it has been suggested that the inflections from the concave shape of the steelpan bowl to the convex shape of the note areas serves as a boundary where mechanical waves are partially reflected. High speed ESPI movies of strikes on a low tenor steelpan were acquired in an effort to search for evidence of these reflected waves.
Study of the impact of material on clarinet-like instrument: Correlation between impedance measurement and musician tests
Authors: Hovasse Louise , Cottier Jonathan , Selmer Jerome , Gibiat Vincent
Published: November 2017

The acoustical effect of the material of woodwind instruments seems to be the favorite discussion subject between acoustician and instrument maker. Indeed in scientific literature, different hypothesis are demonstrated by musician tests or scientifically experimentation. This study, based on the acoustical input impedance measured on tubes and clarinets, as well as musician tests, tends to highlight material could have part of influence on the acoustic of woodwind instrument. Moreover, correlations between measurements and musician tests are found. Indeed, three clarinets have been tested by musicians, one as reference in African Blackwood, one half synthetic-half African Blackwood with the same density as the reference instrument and one in other species of wood with a lower density than the reference instrument. The correlation between measurement and musicians tests is that the instrument felt more brilliant is the one with the highest quality factors on the impedance peaks and reflection coefficients, whereas the instrument felt duller have the smallest quality factors and reflection coefficients. Since the quality factor and the reflection coefficient are linked to the visco-thermal losses, themselves depending on the surface condition, the acoustic of the clarinet-like instruments appears to be more impacted by the surface condition than the material itself.
Electroacoustic modeling and characterization of an ultrasonic projector
Authors: Feuillard Guy , Tran Huu Hue Pascal , Saadaoui Naoufal , Nguyen Van Thien , Lethiecq Marc , Saillant Jean François
Published: November 2017

Ultrasonic projectors are new type ultrasonic transducers that take advantage of the ultrasonic wave emitted on the rear face of the transducer. It consist in an acoustic symmetrical design where both waves generated on the faces of the piezoelectric ceramic are collected in phase with a 45° angle wedge resulting in an increase of the sensitivity. In this case, the absence of backing endows that the conventional design rules of a transducer cannot be directly applied. In this work, the electroacoustic modeling and characterization of such projector is reported. Using the KLM well known model, the electroacoustic response of a projector in based on a piezoelectric ceramic with one matching layer is calculated. Simulations show that the optimal acoustic impedance of the matching layer should be lower than for conventional transducers leading to a bandwidth of approximately 50%. The characterizations of such transducer based on PZ27 (Meggit/Ferroperm) and a lead free material PIC700 (PI Ceramic) have been carried out. Bandwidth and sensitivity are reported. They are found close to the simulation results and demonstrate that these new types of transducers has to be designed according new trends compared to conventional transducers.
Anomalous scattering effects from bi-anisotropic inclusions and metamaterials
Authors: Quan Li , Alu Andrea
Published: November 2017

The acoustic scattering properties of small particles are typically dominated by weak monopolar or dipolar effects, associated with their nature and geometry. As large collections of them form materials, these features determine the overall response to sound of the object we have around. Recent work on acoustic bi-anisotropic acoustic inclusions has shown that, by breaking geometrical and time-reversal symmetries, one can realize constitutive relations that couple pressure fields to dipole radiation and velocity field to monopole radiation in non-trivial ways. In this talk, we use these properties to induce anomalous scattering properties in small inclusions, including unidirectional scattering cancellation, non-reciprocal scattering responses, and directive or sharp scattering resonances. We also consider the use of active acoustic particles to further extend the available degrees of freedom in scattering engineering, and explore unusual parity-time symmetric responses in acoustics. By combining several of these complex inclusions to form acoustic metamaterials, we also investigate the unusual material responses offered by this design approach, which goes beyond what available in natural materials, offering new degrees of freedom for acoustic engineering.
Optimal attenuation caused by boundary impedance in acoustic waveguides
Authors: Kelsten Matthew , Norris Andrew
Published: November 2017

Non-Hermitian systems can exhibit “exceptional points” (EPs) at which modes coalesce. The connection between EPs and acoustic damping goes back to the observation of Cremer (1953) that optimal attenuation in a duct occurs when the two lowest modes have equal complex-valued eigenvalues, although the physical basis for this effect remains unclear. In an attempt to understand Cremer’s observation, we consider the model case of a two-dimensional waveguide with different impedance conditions on the two boundaries. This allows us to determine the complete set of all possible pairs of passive impedance conditions that give rise to EPs, and from these to select impedances appropriate to a particular frequency bands. The non-separable, and generally non-symmetric, mode shapes are described. The theoretical findings are linked to realistic passive impedance values based on various models for boundary impedance, such as perforated and porous panels. These comparisons are discussed to illustrate the feasibility of optimized wall impedances in absorbing sound passing through ducts. [Work supported by NSF.]
The relation of auditory perceptual ratings of nasality to nasal port area in connected speech
Authors: Story Brad H. , Bunton Kate
Published: November 2017

Modeling can be used to understand the relation of articulatory movement to the acoustics and perception of speech. Published studies of velopharyngeal orifice size and perceived nasality in clinical populations have not shown a clear relationship between the measures. Two reports based on computational modeling, however, have found a high correlation between ratings of nasality and nasal port area (Bunton & Story, 2012; Bunton, 2013). These studies were based on sustained vowel simulations with nasal port areas ranging from 0 to 0.5 cm2. Expert listeners were able to detect nasality in vowel samples with a nasal port area greater than 0.01 cm2 and nasality rating plateaued with areas greater than 0.16 cm2. The present study extends this work by reporting on nasality ratings based on short connected speech samples simulated with varying nasal port areas. The connected speech samples included either obstruent consonants or approximant consonants to examine whether the relationship between perception and nasal port area varies based on the pressure demands of the speech sounds produced. This work allows for a more complete explanation of the relation between auditory perceptual ratings of nasality and nasal port area. [Work supported by NIH R01-DC011275 and NSF BCS-1145011.]
Nasal rustle: An evidence-based description
Authors: Rollins Michael , Oren Liran , Kummer Ann W. , Willging J. P. , Boyce Suzanne E.
Published: November 2017

“Nasal rustle” (also known as “nasal turbulence”) is a loud nasal distortion that can be heard during speech production in certain children with velopharyngeal insufficiency (VPI). It occurs when there is a leak of airflow into the nasal cavity through a small velopharyngeal opening. While the perception of audible nasal emission—including nasal rustle—is a standard means for the diagnosis of VPI, there is no consensus on the sound generation mechanism. Current hypotheses include aerodynamic turbulence, velar flutter, and bubbling of mucus secretion. This study investigates the correlation between the acoustic signal of nasal rustle and physical movement at the superior velopharyngeal port. Several pediatric VPI patients were recorded via high-speed video nasopharyngoscopy and simultaneous nasometry during production of speech sounds susceptible to nasal rustle. Instances of perceived nasal rustle in the acoustic signal were identified and compared with the high-speed video. A high correlation was found between the bubbling frequency of mucus secretion above the velopharyngeal port and frequencies in the nasal acoustic signal, suggesting that secretion bubbling is a mechanism for generating nasal rustle. From this analysis, an integrated description of nasal rustle invoking physiological, physical, and acoustic principles is proposed.
Detection in an uncertain underwater waveguide
Authors: Michalopoulou Zoi-Heleni , Abdi Ali
Published: November 2017

Detection of signals in oceanic waveguides is complex because of uncertainties in the underwater channel and potentially suboptimal location of receiving phones. Accurate detection and estimation are a direct result of optimization with respect to frequency, environmental parameters, and receiver location. We here study the impact of these parameters on detection and propose methods for improvement, including detection processor calibration for optimal performance. We complement our work by investigating detection performance with real data collected at different sensors in a pool. In addition to conventional hydrophones, we also use vector sensors. The rationale behind using a vector sensor is that particle velocity components may show different noise and channel characteristics such as a different number of modes and different dispersive behavior, which are tightly related to detection. We study several detectors and evaluate their performance. [Work supported by ONR and NSF.]
Angle estimation using a moving PV sensor: Performance assessment
Authors: Sullivan Edmund
Published: November 2017

It is well known that bearing estimation performance, using a moving line array of pressure sensors, can be enhanced by using a Kalman filter to jointly estimate the bearing and source frequency. This is because the bearing dependence of the Doppler can be exploited when the source frequency is known. However, it is also known, based on an observability analysis, that it cannot be done using a single moving pressure sensor. Here, it is shown that if a single moving pressure-vector sensor is used, both the bearing and roll angle can be estimated. If only the vector sensor is used, estimation of these angles can still be done, but the performance is poor. The addition of the pressure sensor allows the motion to be exploited, thus significantly enhancing the performance. This phenomenon is shown theoretically by using a Bayesian Cramer-Rao lower bound calculation. An example using simulated data is shown where the improvement is clearly demonstrated.
Inference regarding the state of mobile underwater object from a small aperture vertical array
Authors: Barros Abner C. , Gendron Paul J.
Published: November 2017

A narrowband source ensonifies an area of interest with an oncoming submerged target in a refractive undersea environment. A vertical linear hydrophone array is employed to infer the depth, range, and speed of the target by resolving a direct path and one interacting surface path. Tracking the target by means of a continuous wave transmission is challenging due to the difficulty of inferring the frequencies and angles of the two returned closely spaced wave vectors. The complex propagation of sound in a refractive medium presents additional challenges for inversion of the wave vectors to range and depth. A Gibbs sampler is employed to construct the posterior joint density of all parameters taking full advantage of the analytic tractability of the conditional densities of the received amplitudes and phases and of the ambient acoustic noise power. The conditional densities of the ordered wave vectors however are constructed numerically by 2-dimensional inverse quantile sampling. The inferred joint posterior density of the target state is obtained by constructing an inverse transformation of the acoustic propagation model that accounts for the depth dependent sound speed. Simulation results demonstrate the approach at received signal to noise ratios below −3dB.
A full-field scattering coefficient for rough interfaces and a modified sonar equation for long-range reverberation
Authors: Ivakin Anatoliy
Published: November 2017

A full-field perturbation approach [A.N. Ivakin (2016), J. Acoust. Soc. Am., 140(1), 657–665] allows modifying two terms of sonar equation for reverberation in complex environments and waveguides with rough interfaces. The first one describes a two-way transmission loss for the full-field intensity in the vicinity of the interface. The second term is a full-field scattering coefficient related to but different from the conventional scattering cross-section per unit area. In particular, the coefficient has a non-zero limit value at small grazing angles of incident and scattered waves defined by the contrast of acoustic parameters at the interface and the power spectrum of roughness. The modified sonar equation allows extremely fast estimating the long-range reverberation based on only one (central) frequency calculation of the transmission loss averaged over a certain span of ranges defined by the used frequency bandwidth, and only one value of the scattering coefficient (at zero grazing angles). No multiple calculations of the reverberation pressure field resulted from Monte-Carlo simulations of random rough interfaces are required. Numerical analysis of ocean reverberation is performed considering different types of rough interfaces: sea-surface, water-sediment interface, buried sediment interfaces, and bottom basement. Model-data comparisons are presented based on results of a recent shallow water reverberation experiment TREX2013. [Work supported by ONR.]
Novel scattering coefficient for characterizing diffusely reflecting surfaces
Authors: Polack Jean-Dominique , Dujourdy Hugo
Published: November 2017

In a recent publication (Acta Acustica 103(2017) 480–491), the authors developed an innovative model for describing diffuse sound fields. Developing the diffusion equation one step further, this model makes use of the full stress-energy tensor to provide supplementary relations between sound intensity and sound energy. In the case of non-Sabine spaces (narrow or flat rooms), the supplementary relations naturally introduce new boundary conditions that can be interpreted as scattering coefficients on the walls, in analogy to the traditional absorption coefficients associated with the boundary conditions of the energy equation. The paper explains how the novel coefficient is obtained, compares its significance with the widespread diffuse field wall diffusion coefficient, and proposes an experimental technique for measuring it. Preliminary results will be presented, the expected range of values for the scattering coefficient explained as well as its link to wall impedance in the case of a locally reacting boundary.
Energetic wave equation for diffuse sound fields
Authors: Polack Jean-Dominique , Dujourdy Hugo , Pialot Baptiste , Toulemonde Thomas
Published: November 2017

The diffusion equation for modeling diffuse sound fields was proposed some fifty years ago on heuristic principles as an extension to Sabine’s diffuse field model, and still receives much attention. In a recent publication (Acta Acustica 103 (2017) 480–491), the authors developed the model one step further, using the full stress-energy tensor to provide the missing relations between sound intensity and sound energy. This introduces some extra terms that, in case of non-Sabine spaces (narrow or flat rooms), can be defined with the help of the boundary conditions in terms of absorption and scattering coefficients on the walls. Integrating the divergence of the stress-energy tensor across the shortest dimensions of the space leads to a propagation equation of the telegrapher type, which can be solved using finite difference time domain simulation. Schemes for one-dimensional (corridors) and two-dimensional (open-space) spaces are proposed, and numerical results compared to measurements in real spaces. The comparison makes it possible to evaluate the absorption and scattering coefficients by an adjustment procedure. The paper discusses the range of values taken by these coefficients and compares them to more traditional building-acoustical coefficients. It also presents under which further assumptions the diffusion equation is recovered.
A micromachined microphone based on the membrane with bias voltage and field-effect-transistor mechano-electrical transduction
Authors: Kim Junsoo , Lee Hoontaek , Seo Donghwan , Jin Jaehyeok , Shin Kumjae , Moon Wonkyu
Published: November 2017

Recently, capacitive-type microphone dominates the MEMS (Micro-Electro-Mechanical-System) microphone market. Since sizes of the electrodes on the membrane and backplate determine the sensitivity of the microphone, there is a limit in reducing the size of the MEMS microphone. Here, we propose a micro-machined microphone consist of the membrane with bias voltage and field-effect-transistor (FET). The difference between the conventional capacitive MEMS microphone and proposed microphone is the Mechano-Electrical transduction mechanism. By biasing the voltage on membrane, the gate voltage is induced depending on the vibration of the membrane, eventually changes the source drain current. In case of a MEMS microphone using the proposed FET and biased membrane microphone, low frequency roll-off according to the energy conversion does not occur, and the size of the membrane and backplate can be reduced as compared with the conventional MEMS microphone, without the degradation of sensitivity. In addition, depending on the biasing condition, amplitude modulation technique to reduce the flicker noise of the FET can be applied, which leads to the higher SNR (Signal to Noise Ratio). Conventional metal-oxide-semiconductor fabrication process and micromachining process were used. In this study, design, fabrication and performance test of the proposed FET microphone are conducted. [Work supported by CMTC, UM15304RD3.]
Acoustical evaluation of quiet time and its impact on patient outcomes
Authors: Weber Jonathan R. , Ryherd Erica E. , Rolfes Myra , Cooper Heather , Cherven Brooke , Darcy Mahoney Ashley
Published: November 2017

As healthcare evolves from focusing on survival to prioritizing patient care, more efforts have been devoted to exploring the characteristics of an optimal environment. Intensive care units (ICUs) often involve more urgent situations that require more medical equipment, in-unit procedures, and staff that all contribute to the noisy soundscape. Recently, administrative noise reduction strategies such as Quiet Time (QT) and behavioral modification and noise awareness programs have gained popularity. The literature typically demonstrates some positive effects from these interventions; however, there are inconsistencies in magnitude and sustainability. We conducted an 18-month, longitudinal study of QT aimed at (a) characterizing the Neonatal Intensive Care Unit (NICU) soundscape more extensively and with newly developed metrics and (b) determining the impacts of sound on patient physiological responses. Results show some evidence of trends toward decreased noise levels after QT implementation. For example, QT generally resulted in lowered occurrence rates, indicating a decreased number of high-level noise events. Additionally, spectral data showed significant decreases in level across the vocal frequency range and improved speech intelligibility index scores with QT implementation. Ultimately, these results begin to provide a template for determining the optimal soundscape to aid more targeted administrative and architectural design strategies.
Electric vehicles—Safe and quiet with acoustic vehicle alerting systems?
Authors: Weinandy Rene , Schade Lars , Gebhardt Jan
Published: November 2017

One of the most important environmental issues in densely populated areas is the problem of noise. Traffic noise from cars, railway vehicles and airports located in close proximity to cities is not only annoying for residents; it also leads to serious health issues and has an enormous negative economic impact. Due to this, it is of primary importance to make our cities quieter. The German Environment Agency is working on noise and its effects on humans, especially with respect to policy and regulation. Currently there is a strong debate here in Germany—as in many other parts of the world—about road vehicles that rely, in whole or in part, on alternative drive trains. On the one hand, there are positive environmental benefits expected from these “hybrid or pure electric” road vehicles. On the other hand, these vehicles are thought to pose a risk to blind and low vision pedestrians, due to their lower noise emissions at approach. To address this concern, the European Union has legislated that future hybrid and pure electric cars must be equipped with acoustic vehicle alerting systems (AVAS). The presentation provides a critical assessment of the effectiveness of AVAS and of their negative side effects.
Induction loop assisted listening system case study in a Catholic church
Authors: Manley David , Bridgewater Benjamin
Published: November 2017

A Catholic church in Metro Denver, Colorado area, was undergoing major renovations for the first time since the 1970s, and wished to incorporate an induction loop assisted listening system as an amenity for their aging members. The pastor indicated the Church has lost a number of parishioners due to the lack of an assisted listening system. While the Church installed a temporary radio frequency assisted listening system until renovations could be complete, a permanent and integrated system was desired. The case study presents coordination with Church, the loop system manufacturer, testing of the existing space for metal loss, and design results.
Phase transition characterization based on acoustic reverberation time
Authors: Achdjian Hossep , Bustillo Julien , Blanc Laurianne , Arciniegas Andres , Doumit Nicole , Lethiecq Marc
Published: November 2017

Non-destructive monitoring of a material’s state during its physicochemical transformations is of interest for several industrial fields including food processing, such as milk-derived products, or cosmetics. The use of ultrasound to provide reliable information about physicochemical properties is becoming increasingly popular. Indeed, ultrasonic techniques have the main advantage of being rapid and non-invasive methods that allow parameters such as product composition, structure, and physical state to be obtained. Yet, classical techniques are limited to the characterization of the medium along the propagation path using the first wave packets. Here, we propose an alternative technique based on the study of the reverberated waves, classically used in room acoustics. In previous works, this method has shown its capability to characterize materials as well, with the advantage over classical techniques to address a medium in its whole structure. In this context, the determination of sol-gel phase transition time of Salol using this method is presented. Measurements are performed in an aluminum mold using five piezoelectric (PZT) patches, one being used as emitter and the others as receivers. The mean reverberation time over four receivers has been studied and its evolution is shown to lead to a good estimation of the phase transition time.
Compressibility-near-zero acoustic supercoupling
Authors: Byrne Matthew S. , Esfahlani Hussein , McDermott Matthew J. , Alu Andrea
Published: November 2017

Epsilon-near-zero supercoupling is a widely-researched topic in electromagnetics. This phenomenon takes advantage of media with near-zero dielectric permittivity to build waveguide coupling channels which can, in principle, support unitary transmission and complete phase uniformity, independent of the length and height of the coupling channel. In this effort, we present the possibility that an analogous, extraordinary coupled-mode phenomenon exists in acoustics, which we call compressibility-near-zero (CNZ) supercoupling. Prior works have required the presence of periodic membrane resonances in order to observe near-zero index coupling. We have shown, for the first time, theoretically and experimentally, that the phenomenon can be observed without the use of membranes. We envision this development as a first step towards experimentally realizing spatiotemporally-modulated acoustic non-reciprocal devices which take advantage of these physical principles.
Toward a dynamic theory of vowel production
Authors: Hu Fang
Published: November 2017

Vowels are traditionally classified into monophthongs, diphthongs, triphthongs, and in some rare cases, tetraphthongs. However, there is a long debate on the complexity of vowels in the literature. Some phoneticians view diphthongs as a single vowel with phonetically complex nucleus, while others treat diphthongs as a sequence of two vowel elements. This paper reports recent developments in vowel researches in Chinese dialects, and argues for an integral account for vowel production. First, fine-gained phonetic details from Mandarin, Wu, Jin, Hui, Min, and Hakka reveal that falling diphthongs and rising diphthongs differ in temporal organization, spectral property, and spectral dynamics. Second, there is no dichotomy, but a continuum between monophthongs and diphthongs. Comparisons between four Hui dialects reveal how the process of diphthongization develops from a more monophthong-like stage to a more diphthong-like stage. In conclusion, the production data from Chinese dialects support an integral account for vowel production. Monophthongs are composed of a static spectral target, diphthongized vowels and falling diphthongs are composed of a dynamic spectral target, and rising diphthongs are sequences of two spectral targets.
Acoustic features of spontaneous and read conversational and clear speech produced in simulated acoustic environments
Authors: Ferguson Sarah H. , Hunter Eric J. , Staples Jessica J.
Published: November 2017

Speech production can differ depending on how speech is elicited (e.g. spontaneous speech, read text, speaking style instructions, the speaking environment). In most studies in which different speaking styles have been elicited via instruction (e.g., clear speech) or via the speaking environment (e.g., Lombard speech), the talkers have read printed materials. There is evidence that the acoustic features of clear speech elicited by reading are similar to those observed in semi-spontaneous interaction between two interlocutors, but that clear speech changes are of a greater magnitude in the read speech than the semi-spontaneous speech [V. Hazan and R. Baker, J. Acoust. Soc. Am. 130(4), 2139–2152, 2011]. The present study examines the effects of two speaking style instructions (conversational and clear) and four simulated listening environments (quiet, 55 dB SPL of white noise, 63 dB SPL of white noise, and a reverberant environment) presented via earphones for three types of speech materials: read sentences, read passages, and spontaneously produced picture descriptions. Acoustic features relevant to clear speech and Lombard speech will be compared among the three material types.
A case report of nasal fricatives with grimacing: Evidence for spectral marking of the /s/-/ʃ/ contrast
Authors: Eshghi Marziye , Zajac David J.
Published: November 2017

A three-year old girl with repaired bilateral cleft lip and palate was observed to produce anterior nasal fricatives (ANFs) with grimacing during video administration of GFTA-3. ANFs are learned maladaptive articulations used to replace oral fricatives. They are produced by occluding the oral cavity and forcing all airflow through an open velopharyngeal (VP) port that results in turbulent noise at the anterior liminal valve of the nose. Although the girl had normal hearing at the time of testing, she had a history of conductive hearing loss and ventilation tubes. Pressure-flow testing confirmed VP dysfunction and a small nasal area during breathing. The girl appeared to grimace more severely during production of targeted /ʃ/ as compared to /s/ sounds. Greater grimacing on /ʃ/ was confirmed by a forced-choice task with three raters who independently viewed randomized video segments of /s/-/ʃ/ words. Spectral moment analysis revealed higher spectral mean, more negative skewness, and higher kurtosis for ANFs substituted for /s/ as compared to /ʃ/ sounds. We conclude that the girl used a nasal grimace as an articulatory gesture—perhaps learned during speech therapy—to spectrally mark the /s/-/ʃ/ contrast by modulating the length and cross-sectional area of the anterior nasal valve. [Research reported in this publication was supported by the National Institute of Dental & Craniofacial Research of the National Institutes of Health under Award Number 1R01DE022566-01A1.]
On simultaneous electromagnetic articulography and electroglottography data acquisition
Authors: Harper Sarah , Lee Sungbok , Byrd Dani , Goldstein Louis
Published: November 2017

Simultaneous measurements of speech articulator movement and laryngeal activity are desirable for obtaining a picture of the coarticulatory behavior between oral articulators and laryngeal vocal fold behavior. However, since electroglottography (EGG) use the application of a weak current across the larynx, which is in close proximity to the oral vocal tract, there is a possibility that its use may interfere with the sensor voltage fluctuation measurements used in electromagnetic articulography (EMA). In order to investigate any hypothetical interference effect, data was collected using Northern Digital Instruments’ Wave articulograph with Glottal Enterprises’s EG2-PCX electroglottograph. Datasets were collected from one male and one female speaker—both with simultaneous EMA and EGG and, for comparison, with EMA alone. Means and standard deviations of inter-sensor distances for static (i.e., reference) and moving (e.g., tongue tip, lip, and jaw) EMA sensor trajectories were compared across the two collection conditions for possible interference effects. Preliminary results find no discernable differences in inter-sensor distances for either static or moving EMA sensors between the with- and without-EGG conditions. If this finding is maintained for additional speakers, NDI EMA data and GE EGG signals may be collected simultaneously without adverse effects on the measurement. [Work supported by NIH.]
Oral and nasal vowels effects on subglottal pressure
Authors: Demolin Didier , Trouville Roland , Wang Ruolan , Signorello Rosario
Published: November 2017

This paper investigates the effect of oral and nasal vowels on subglottal pressure. The vowels /i, e, a, o, u, ø, œ̃, õ/ were produced on a specific tone by two Belgian French speakers (male and female). The tone frequency was given to the speakers while producing the vowels through a set of headphones connected to a synthesizer. Three frequencies were given at comparable intensities (male speaker: A, C, E; female speaker: C, F, A). Both speakers produced the set of vowels in a mask, with the mouth at a quasi-constant distance from the microphone. In addition to the acoustic signal, the subglottal pressure was recorded by tracheal puncture with a needle inserted between the cricoid cartilage and the first tracheal ring. Measurements show that both speakers produced each of the vowels with stable F0 (2 Hz difference variation from the given tone). One interesting observation is that there is a substantial difference in subglottal pressure between oral and nasal vowels. Both speakers produced nasal vowels with a lower subglottal pressure when compared to oral vowels. Mean differences between both set of vowels were quantified at 2.15 hPa. Nasal vowels were found to have lower intensity than oral vowels.