bluuebunny/crossref_metadata_2025 huggingface dataset:
Potential changes in aircraft noise sound quality due to continuous descent approaches
Authors: Sahai Abhishek K. , Pereda Albarran Miguel Yael , Snellen Mirjam
Published: June 2017

This paper presents an analysis of how flying Continuous Descent Approaches (CDAs) can affect the quality of sounds that aircraft produce in airport vicinities. It is well known that CDAs present potential benefits in terms of community noise impact with reductions in excess of 5 dBA in peak noise levels. It is however unclear if these reductions in A-weighted level, which is a poor predictor of perceived annoyance, also correspond to an improvement in the quality of the aircraft sounds that reach the residents on the ground. A real comparison can only be made by comparing the sounds an aircraft produces while flying a CDA with a standard approach procedure. A short-range and a long-range aircraft are simulated to fly a standard approach procedure and a CDA with 3, 4, and 5 degree glideslope angle. The noise produced over both approach procedures is then auralized at representative ground locations, and the sounds are analyzed for changes in sound quality. Quantifying the changes in the aircraft sounds in terms of sound quality metrics provides much clearer information regarding how the sound the residents hear has changed, and if the CDAs actually result in an improved sound quality and hence lower annoyance.
Reduced aerodynamic drag concepts for acoustic liners
Authors: Jasinski Christopher , Corke Thomas
Published: June 2017

The objective of this paper is to describe the development of reduced aerodynamic drag concepts for acoustic liners in turbofan engine nacelles. Conventional acoustic liners help aircraft to achieve U.S. governmental noise regulations, however they are responsible for a measurable increase in the total aerodynamic drag of the aircraft. As regulations on commercial aircraft noise become more strict, additional surfaces may be covered with acoustic liner, heightening the need for the understanding and reduction of aerodynamic drag caused by liners. A linear force balance has been designed at the Mach 0.6 Wind Tunnel at the University of Notre Dame to evaluate the aerodynamic and acoustic characteristics of both conventional and 3D-printed liner samples. Through multi-parameter characterization, reduced drag concepts for future liners have been created. This paper will discuss the experimental work done to develop these reduced drag concepts, outline the future work to be done, and discuss the potential acoustic coupling effect on aerodynamic drag.
Environmentally friendly parametric alarm for alerting marine mammals of approaching vessels
Authors: Gerstein Edmund R. , Gerstein Laura A.
Published: June 2017

Marine mammals are vulnerable to boat, barge, and ship collisions. Although more commonly identified and reported in busy coastal areas, collisions are not restricted to shipping lanes or shallow water environments. A common denominator is that they all occur near the surface. Here the acoustical laws of reflection and propagation significantly limit the ability of marine mammals to hear and locate the sounds of approaching vessels. Acoustic measurements from controlled ship passages through vertical hydrophone arrays demonstrate the confluence of factors that poses auditory detection challenges for both whales and manatees. A highly directional, environmentally-friendly, low intensity underwater parametric alarm has been developed to mitigate these challenges & safely alert marine mammals of approaching vessels. The efficacy has been demonstrated with wild manatees. Ninety-five percent of manatees during alarm-on trials elicited avoidance reactions while only 5% of manatees during alarm-off trials elicited any change in behavior. The mean distance at which manatees reacted to boat approaches during alarm-on trials was also 20 m compared to only 6 m for alarm-off trials (F= 218.4 df = 1, p< 0.01). Counter-intuitive to speed reduction laws, slow vessels can be more difficult for marine mammals to detect and locate. The low intensity, directional alarm assures animals can detect & locate vessels at distances sufficient to avoid injury. [Funded by DOD Legacy Natural Resource Management Program, USFWS Permit MA063561-4.]
Vibro-acoustic imaging development for microstructure characterization and metrology
Authors: Smith James A. , Larsen Eric D. , Zuck Larry D.
Published: June 2017

Vibro-acoustics (VA) is being developed into a portable scanning infrastructure for a novel material characterization technique focused on nuclear applications to characterize fuel, cladding materials, and structures at the Idaho National Laboratory (INL). The proposed VA technology is based on ultrasound and acoustic waves; however, it provides information beyond what is available from the traditional ultrasound techniques and can expand the knowledge on nuclear material characterization and microstructure evolution. VA is a three-dimensional (3D) imaging modality based on ultrasound-stimulated acoustic emission. VA uses the force caused by the beating of two frequencies to generate an acoustic emission signal. Due to absorption or reflection, the energy density in the object at an acoustic focal point changes to produce a “radiation force.” This force locally vibrates the object, which results in an acoustic field that depends on the characteristics of the object at that point. This acoustic field is detected for every point in the object; the resulting data is used to make an image of the object’s mechanical properties. This paper will focus on the development of a portable scanning system to image in situ the microstructure of materials used in nuclear applications.
The role of self-motion processing in impairments of the spatial perception of auditory scenes
Authors: Brimijoin W. Owen , Naylor Graham , McLaren Andrew
Published: June 2017

Natural auditory scenes typically include some motion. When this motion is the result of a moving listener, as is often the case, an accurate spatial percept requires that the listener be able to: 1) determine sound source location over time, 2) determine the extent and characteristics of his/her own motion, and 3) integrate these two pieces of information together. We assembled a battery of tests to evaluate these three criteria in normal, hearing-impaired, and balance-impaired listeners. The battery consists of a dynamic visual acuity test to estimate the listener’s self-motion processing, a measure of the minimum audible movement angle to determine source-motion acuity, and an adapted version of a previously published dynamic front/back illusion to examine the ability to combine self and sound-source motion. We found that listeners with potential vestibular impairment were more likely to have larger differences between source-motion acuity and self-motion integration acuity. This finding and the observed inter-subject variability together underscore the sensitive nature of the ongoing comparison between one’s own motion and the motion of the acoustic world. [Work supported by the MRC (Grant No. U135097131) and the Chief Scientist Office of the Scottish Government.]
Evaluation of scene analysis using real and simulated acoustic mixtures: Lessons learnt from the CHiME speech recognition challenges
Authors: Barker Jon P.
Published: June 2017

Computational auditory scene analysis is increasingly presented in the literature as a set of auditory-inspired techniques for estimating “Ideal Binary Masks” (IBM), i.e., time-frequency domain segregations of the attended source and the acoustic background based on a local signal-to-noise ratio objective (Wang and Brown, 2006). This talk argues that although IBMs may be a useful stand-in when evaluating signal-processing systems, they can provide a misleading perspective when considering models of auditory cognition. First, there is no evidence that human cognition computes or requires an explicit binary mask representation (ideal or otherwise). Second, evaluation of an IBM requires artificially-mixed acoustic scenes in order to provide access to the ground truth mask. It is possible that systems that work well on artificially mixed acoustic scenes will fail to generalize to real data. The danger in predicting real performance from results obtained on artificial mixtures is seen in an analysis of systems submitted to the recent CHiME distant microphone speech recognition challenges which evaluates on both types of data (http://spandh.dcs.shef.ac.uk/chime). It is argued that rather than presume specific internal representations, auditory scene analysis systems can be best evaluated by direct comparison of human and machine percepts, e.g., in the case of a speech recognition task, comparison of human and machine transcriptions at a phonetic level.
The auditory experience of infants born prematurely
Authors: Monson Brian B.
Published: June 2017

The third trimester of gestation is a time of rapid auditory and brain development, and auditory experience during this period affects brain development. For example, newborns exhibit auditory learning and memory for acoustic stimuli frequently heard in utero. Preterm infants in the neonatal intensive care unit (NICU) during the third-trimester-equivalent period have a vastly different auditory experience than their fetal peers in utero, but the acoustic differences between these two environments are not well defined. The goal of quantifying these differences is to better understand and even predict their impact on auditory processing deficits exhibited by preterm infants later in childhood. Here I will present data describing the acoustic environment of the NICU, including noise sources, alarms, and sound levels measured in a NICU in a Boston hospital. One striking finding is that, in stark contrast to the intrauterine environment, periods of silence in the NICU are abundant. The consequences of this atypical perinatal acoustic exposure on auditory and brain development are unknown.
Modeling high frequency broadband acoustic fields inside rectangular and cylindrical enclosures using an energy-intensity boundary element method
Authors: Bliss Donald B. , Raudales David , Michalis Krista A. , Franzoni Linda P.
Published: June 2017

Accurate prediction of high frequency broadband acoustic fields inside enclosures with curved boundaries typically requires time consuming frequency-by-frequency numerical techniques. A quick solution is developed for general enclosure shapes using an energy-intensity boundary element method, previously tested for rectangular geometries and now extended to cylinders with flat or spherical endcaps. Derived from first principles, which are reviewed, the approach uses uncorrelated spreading energy-intensity boundary sources to directly solve for the steady-state mean-square pressures. The enclosure boundary is discretized into radiating panels that account for interior energy transfer and satisfy prescribed reflection and absorption boundary conditions. Half-space orthogonal spherical harmonics serve as basis functions to emulate both diffuse and specular reflections. Panel interactions are calculated by an energy-accurate quadrature technique and studied for curved boundaries. Computationally intensive benchmark solutions are developed for verification. A fully correlated Helmholtz solution is derived for the cylindrical enclosure using a novel internal scattering approach to calculate high frequency pressure, and numerically integrated over a third-octave band. Comparisons between the fully correlated solution and the energy method for enclosures of various aspect ratios reveal excellent agreement. Simulations are also presented contrasting interesting behavioral differences between diffuse and specular reflection fields.
Predicting the variance of the frequency-averaged energetic response in hybrid finite element—Statistical energy analysis
Authors: Reynders Edwin , Langley Robin S.
Published: June 2017

In this contribution, the hybrid finite element-statistical energy analysis method is extended such that not only the mean and the ensemble variance of the harmonic system response can be computed, but also the ensemble variance of the frequency band-averaged system response. The computed variance represents the uncertainty that is due to the assumption of a diffuse field in components of the hybrid system. The developments start with a cross frequency generalization of the diffuse field reciprocity relationship between the total energy in a diffuse field and the cross spectrum of the external loading. By making extensive use of this generalization in a first-order perturbation analysis, explicit expressions are derived for the variance of the vibrational energies in the diffuse components and for the variance of the cross spectrum of the response of the deterministic components. These expressions are extensively validated against Monte Carlo analyses of systems consisting of connected plates, in which diffuse fields are simulated by randomly distributing small concentrated masses, acting as wave scatterers, across the diffuse components.
Reading aloud: Acoustic differences between prose and poetry
Authors: Nenadic Filip , Tucker Benjamin V.
Published: June 2017

Research on silent reading has shown that text genre influences the way texts are read, including differences between prose and poetry (e.g., Zwaan, 1994; Hanauer, 1998). There is little data examining whether text layout (prose vs. poetry) affects the way it is read aloud by non-expert readers, and, if yes, how do readers express those differences acoustically. Native speakers of Serbian (N = 28) and English (N = 37) read aloud twenty short texts in their native language. Stimuli were original texts that were acceptable as both prose and poetry, written by young published authors. Each text was formatted in four layouts (prose left aligned and justified, a single stanza and verses in multiple stanzas). Each participant saw each text in only one of these layouts. Separate mixed effects logistic regression analyses were performed for each language, testing whether prose vs. poetry layouts influenced the silent period and utterance duration, pitch, and intensity values of the productions. Differences and similarities between reading prose and poetry and between Serbian and English participants are discussed.
Spectro-temporal cues for perceptual recovery of reduced syllables from continuous, casual speech
Authors: Dilley Laura , Arjmandi Meisam K. , Ireland Zachary
Published: June 2017

Function words may be highly reduced, with little to no discontinuity marking their onsets to cue their segmentation from continuous speech. The present study investigated whether reduced function words lacking onset discontinuities have residual timing cues that could be used for word segmentation. Participants (n = 51) briefly viewed sentences and spoke them from memory to elicit casual speech. They were randomly assigned to either a “function-word present” condition (n = 29) in which experimental items contained a critical function word expected to frequently blend spectrally with context, or a “function-word absent” set (n = 22) with phonetically matched items lacking the critical word. Acoustic analyses confirmed that in “function-word present” sentences, critical words lacked detectable onset discontinuities 60% of the time. Critically, in the “function-word present” condition, portions of speech containing critical function words were longer, both in terms of absolute duration and normalized for context speech rate, compared with matched portions in the “function-word absent” condition, even when the former were highly reduced and lacked onset discontinuities. These findings suggest that relative duration cues provide substantial information which may be used by listeners for segmentation of highly reduced syllables from continuous speech. [Work supported by NSF Grant BCS-1431063.]
Prosodic cues to psychosis risk
Authors: Cibelli Emily , Cole Jennifer , Mittal Vijay , Goldrick Matthew
Published: June 2017

Schizophrenia is known to impact prosody, often described as “flat affect.” Individuals with schizophrenia show reduced F0 variability relative to neurotypical individuals (Rapcan et al. 2010). However, the speech of adolescents at high risk for psychosis in the prodromal (pre-diagnosis) stage has not been investigated, leaving open the question of whether speech prosody might be an early signal of symptoms associated with psychotic disorders. To investigate this issue, the speech of 18 ultra high-risk (UHR) youth (ages 16-21) was compared to 18 age- and gender-matched controls. F0 (pre-processed for smoothing and error correction) was extracted from 10-minute segments of speech recorded during clinical interviews. Using LDA classification, F0 summary statistics (mean and variability) separated male UHR and control speakers (69% accuracy) but not female speakers (42% accuracy), consistent with gender differences in psychosis onset during adolescence (Ochoa et al., 2012). Linear models of symptoms measured by the Structural Interview for Prodromal Syndromes (Miller, 2003) found that F0 mean and variability predicted negative symptoms in UHR speakers when controlling for age and gender. These results suggest that prosodic markers documented in individuals with psychosis may also be present in prodromal populations, pointing to speech as a potential biomarker for psychosis risk.
Effects of dialect and syllable onset on Serbian tone timing
Authors: Karlin Robin P.
Published: June 2017

In recent years, the c-center effect has been posited as the main coordinative structure for lexical tone. This has two predictions: (1) the timing of tone gestures is affected by syllable onset complexity, and (2) tone gestures will start relatively late compared to the first onset consonant. However, little work has investigated these predictions, thus far focusing on languages with few word-initial clusters. In this acoustic study, I examine two dialects of Serbian, a pitch-accent language that allows word-initial sonorant-sonorant clusters such as /ml/. In both dialects, the H(igh) tone excursion starts later in syllables with complex onsets, in accordance with prediction 1 and is suggestive of a c-center structure. The dialect comparison addresses the second prediction, as Valjevo Serbian has early peaks, and Belgrade Serbian has late peaks. The results show that the early peaks in Valjevo Serbian are due to a combination of both earlier H onset and shorter pitch excursion, which suggests that at least one of the dialects is not using a c-center structure. Based on these results, a model of tonal representation is proposed that has implications for the possible coordinative structures of lexical tone.
Numerical study on the effect of various parameters on beamforming performance and the estimation of particle velocity using a circular array
Authors: Kim Sea-Moon , Byun Sung-Hoon
Published: June 2017

Numerous studies on beamforming techniques have been done for the estimation of source direction with an array. The conventional beamforming (delay and sum), MVDR, and MUSIC are some examples. Recently, the frequency difference beamforming was also introduced for applications to high frequency ranges or the elimination of the aliasing effect. This talk compares performance of the beamforming techniques including frequency difference beamforming using a circular array. The effects of the various parameters, such as number of sensors, array radius, frequency range, and SNR, on the beamforming performance are studied. The error analysis for the estimation of particle velocity is also discussed. [This work was financially supported by the research project PES9020 funded by KRISO.]
Temporal-spatial distributions for a repertoire of fin whale vocalizations from directional sensing with a coherent hydrophone array
Authors: Garcia Heriberto A. , HUANG WEI , Makris Purnima R.
Published: June 2017

The ability to monitor and differentiate vocalizations from a given marine mammal species can be challenging with single sensor measurements when there are multiple marine mammal species vocalizing in close proximity and when the vocalizations have not been observed or documented previously. Here we employ a large-aperture coherent hydrophone array system with directional sensing to detect, localize, and classify a repertoire of fin whale vocalizations using the passive ocean acoustic waveguide remote sensing (POAWRS) technique. The fin whale vocalizations are comprised of their characteristic 20 Hz centered pulses, interspersed by 130 Hz centered upsweep calls, and other vocalizations with frequencies ranging between 40 and 80 Hz. The directional sensing ability of POAWRS is essential for associating various call types to fin whales after long term tracking of the vocalization bearing-time trajectories and localizations over multiple diel cycles. Here, we quantify the relative diel occurrence of the three distinct fin vocalization types and apply the results to infer their behaviors as a function of the observation region.
From Canton to the Curie brothers: The dawn of sonar
Authors: Ainslie Michael A. , Hackmann Willem D.
Published: June 2017

Toward the end of the First World War, Paul Langevin and Robert Boyles developed the first underwater echo-ranging systems capable of detecting and localizing submarines, with important consequences for the outcome of the Second World War. Their invention involved the use of quartz transducers for initial generation of sound and reception of the echo, and vacuum tubes for amplification of the (much weakened) received signal. The distance to the object responsible for the echo could be deduced from the two-way travel time and known speed of sound. The advances in scientific knowledge leading to these technologies are traced from the discoveries of the compressibility of water (1762, John Canton), thermionic emission (1853, Edmond Becquerel), and piezoelectricity (1880, Jacques and Pierre Curie).
Sonar science and technology in Russia in the 20th century
Authors: Godin Oleg A.
Published: June 2017

Russian underwater acoustics traces its roots to the 19th century empirical sound propagation studies on the Sea Devil submarine and theoretical predictions of guided propagation in shallow water. During the World War II, the acute needs to save lives and contribute to the war effort led to rapid expansion of acoustic research and development, especially in mine countermeasures. The growth continued in the post-war years until the USSR collapse and was inspired by the opportunities for naval and civilian applications, which had been opened up by the discovery of the SOFAR channel and deeper understanding of the ocean physics. This paper will briefly review some milestones of underwater acoustic research and development in Russia, from Mikhail Lomonosov to Leonid Brekhovskikh and from Admiral Makarov’s current velocity probe to sonars on early nuclear-powered submarines. Applications of the sonar to improve navigation and characterize the underwater environment will be emphasized.
Application of smoothed finite element method to acoustic scattering from underwater elastic objects
Authors: Chai Yingbin , Gong Zhixiong , Li Wei , Li Tianyun
Published: June 2017

In this work, the smoothed finite element method (S-FEM) is employed to solve the acoustic scattering from underwater elastic objects. The S-FEM, which can be regarded as a combination of the standard finite element method (FEM) and the gradient smoothing technique (GST) from the meshless methods, was initially proposed for solid mechanics problems and has been demonstrated to possess several superior properties. In the S-FEM, the smoothed gradient fields are acquired by performing the GST over the obtained smoothing domains. Due to the proper softening effects provided by the gradient smoothing operations, the original “overly-stiff” FEM model is softened and the present S-FEM possesses a relatively appropriate stiffness of the continuous system. Therefore, the quality of the numerical results can be significantly improved. The numerical results from several typical numerical examples demonstrate that the S-FEM is quite effective to handle acoustic scattering from underwater elastic objects and can provide more accurate numerical results than the standard FEM.
Modal analysis of split-step Fourier parabolic equation solutions in the presence of rough surface scattering
Authors: Aslan Mustafa , Smith Kevin B.
Published: June 2017

Determining accurate solutions of acoustic propagation in the presence of rough surface scattering is of significant interest to the research community. As such, there are various approaches to model the effects of rough surface scattering. Typically, the models used assume an idealized pressure release condition at the sea surface boundary. This boundary condition can easily be accommodated through a variety of modeling techniques for flat surfaces, but it is necessary to introduce additional complex methods in numerical models for rough surfaces. Parabolic equation (PE) models utilizing split-step Fourier (SSF) algorithms have been employed to treat the rough surface displacements. These include methods such as the field transformational technique (FFT), and direct modeling of the physical water/air interface discontinuity. Previous work highlighted phase errors in SSF-based models with large density discontinuities at the interfaces, which were minimized by employing a hybrid split-step Fourier/finite-difference approach. However, such phase errors were largely absent in the presence of rough surface scattering. In this work, the PE solutions are decomposed into normal modes in order to determine which modes dominate the phase error in the presence of flat surfaces, and to confirm that these modes are highly scattered in the presence of rough surfaces.
Bertram Kinzey, Jr.: Teaching across generations
Authors: Siebein Keely
Published: June 2017

Bertram Kinzey, Jr., is an educator, author, acoustician, organ builder, architect, and mentor to many in the world of architecture and architectural acoustics. This paper looks at several meaningful personal accounts experienced by the author growing up. This paper examines several of the many people he directly impacted though his professorship, research and practice, and how they have in turn impacted others. It also provides examples of a second generation of people who have benefited from those he directly impacted and how they have gone on to promulgate Bert’s ideas throughout our field and the world. Mr. Kinzey has influenced an ever-expanding web of multiple generations of architects and architectural acousticians around the world.
Comparison of methods used in design simulation and in emulation of electrical and acoustic systems for audio
Authors: Rollow Douglas
Published: June 2017

Contemporary audio recording and reproduction systems offer exceptional signal quality in terms of bandwidth, resolution, and linearity. Simulations used in the design and analysis of acoustic spaces, electroacoustic transducers, and electronic components are effective in predicting specific metrics of performance, but end-to-end system simulation would be exceedingly difficult even over extended run time. In media production workflows, emulation is used to create perceptually useful renderings of these same systems, with the real-time digital signal path providing emulation of acoustic environments coupled with transducers, and of nonlinear euphonic elements. These algorithms serve some of the same function as those in the design tools, and the present work uses the opportunity to compare engineering goals, economic constraints, and performance requirements.
Predicting sound radiation and sound transmission in orthotropic cross-laminated timber panels
Authors: Santoni Andrea , Bonfiglio Paolo , Fausti Patrizio , Schoenwald Stefan
Published: June 2017

In the last decades, new materials and new technologies which satisfy sustainability and energy efficiency demands have been developed for the building construction market. Lightweight structures are becoming increasingly popular, but it has been proved that they cannot provide satisfactory sound insulation. Therefore a proper acoustic treatment needs to be specifically designed, considering both airborne and structure-borne sound sources. Cross-laminated timber (CLT) elements, for example, have had great success in the last twenty years, both in Europe and North America. CLT plates, due to their peculiar sub-structure, exhibit an orthotropic behavior; they have different stiffness properties along their two principle directions. This paper investigates prediction models for orthotropic plates designed to evaluate sound radiation due to mechanical excitation, and sound transmission due to acoustic excitation. Particular attention is paid to the influence on sound radiation of non-resonant vibration, or near-field vibration, in the case of mechanical excitation. The purpose of these simplified models is to be an efficient tool for acousticians, architects and engineers, helpful in the design process for new buildings and retrofitting of existing ones. The validation of numerical results with experimental data are reported. The applicability of the models and their limitation are finally discussed.
Laboratory mice can behaviorally discriminate between natural and synthetic ultrasonic vocalizations
Authors: Kobrina Anastasiya , Screven Laurel A. , Mahrt Elena J. , Dent Micheal L. , Portfors Christine
Published: June 2017

Mice produce spectrotemporally complex ultrasonic vocalizations (USVs), thought to be important for social interactions such as mating. Previous research has established that mice are capable of detecting and discriminating natural, synthetic, and altered USVs using behavioral methodologies. The current study examined whether mice are capable of discriminating natural USVs from their synthetic USV analogs. Discrimination performance was tested in five adult mice using operant conditioning procedures with positive reinforcement. Mice were trained to nose poke to one hole during a repeating natural or synthetic USV, which would begin a trial. Subjects were required to poke to a second hole when they discriminated a change in the repeating background after a variable interval. The target stimuli were natural and synthetic versions of the same USVs, as well as other USVs. Mice can discriminate between some natural USVs and their synthetic renditions but not others. Discrimination performance across all stimuli was correlated with spectrotemporal similarity. Mice utilized duration, bandwidth, and peak frequency differently for natural and synthetic USV discrimination. These results contribute to our understanding of the ways USVs may be used for acoustic communication in mice. [This work was supported by NIDCD grant R01-DC012302 to MLD.]
Combining echo and hydrodynamic measurements for estimating non uniform sand transport under waves and currents
Authors: Mosquera Rodrigo , Pedocchi Francisco
Published: June 2017

We present recently obtained measurements in the Atlantic coast of Uruguay, with a 1 MHz ADCP (Sentinel V20, Teledyne RDI, USA). The ADCP was deployed at 16 m depth for 4 months using a light weight structure deployed from a small boat. During the deployment, 3.6 m significant high, 12 s peak period waves, and 0.8 m/s currents were recorded. The vertical distribution of suspended sediment in this environment is controlled by the turbulence level induced by both currents and waves. Assuming a representative sediment size and adapting the Rouse-Vanoni profile showed to give results that did not agree with the concentration profiles inverted from the recorded echo profiles. Therefore, a method that combined variations of the sediment size distribution with the turbulence level was developed showing very good agreement with the information from the echo profile. In the developed method, the turbulent sediment diffusivity was computed from the mean current and wave measurements. However, this showed limitations for conditions with strong waves and weak currents. As an alternative, direct measurements of the turbulent fluctuations from the instantaneous beam velocity recordings were used to compute the turbulent diffusivity. In addition, different turbulent diffusivity distributions for combined current-wave conditions were evaluated.
Suspended sediment flux statistics in unidirectional flow, using a pulse-coherent acoustic Doppler profiler
Authors: Wilson Greg , Hay Alex E.
Published: June 2017

An experiment was conducted in the St. Anthony Falls Lab main channel flume, involving sand sediment (d50 = 0.4 mm) in unidirectional flow. The flow conditions were 1 m/s flow rate and 1 m depth, and the bed state consisted of quasi-linear sand dunes with ~1 m wavelength and 10-20 cm height. A pulse-coherent acoustic Doppler instrument (MFDop) measured high-resolution near-bed vertical profiles of velocity and backscatter amplitude at various positions spanning the dune profile. These measurements are used to obtain probability distributions of instantaneous suspended sediment concentration and flux, which are compared to predictions from two stochastic theories. While the stochastic theories were previously developed and validated for low transport rates over a flat bed, the acoustic measurements enabled measurements at a much higher transport rate; despite this, the new measurements remain in remarkably good agreement with the theories.
Finite element optimization of circular element used in lithotripsy and histotripsy piezoelectric transducers
Authors: Thomas Gilles , Chapelon Jean-Yves , Lafon Cyril
Published: June 2017

Multi-element piezoelectric transducers used in shock wave generators for disrupting kidney stones (lithotripsy) or ablating soft tissues (histotripsy) are emitting high amplitude burst waves of one to ten pulses. Thus, most of the signal is sent while the piezoelectric transducers vibrate in a transient state. This work aims at optimizing the design of these elements. A transient finite element model of a piezoelectric circular element is presented. It includes the piezoelectric disk, the epoxy and plastic casing, the surrounding water and the RLC discharge circuit. The model was then used for parametric optimization of the electrical components and the front and back layers. It has been validated by comparing the numerical and experimental results of one 400 kHz, 37.3 mm diameter LT02 element (EDAP-TMS). The surface pressure field as measured by a fiberoptic hydrophone was in good agreement with the simulation. Elements with parameters resulting of optimization from different objective functions, which depend of the application desired, were built and validated with experimental results. The model can be effectively used for the rapid and optimal design of piezoelectric circular elements working in a transient state. [Work supported by an industrial grant from EDAP-TMS.]
Investigation of stone damage patterns and mechanisms in nano pulse lithotripsy
Authors: Yang Chen , Zhang Ying , Zhong Pei
Published: June 2017

Nano Pulse Lithotripter (NPL) utilizes spark discharges of ~30-ns duration, released at the tip of a flexible probe under endoscopic guidance, to break up kidney stones. Different damage patterns have been observed using BegoStone samples, including crater formation underneath the probe tip, crack development from the distal wall, and radial and ring-shape crack initiation in the proximal surface of the stone. Multiple mechanisms have been proposed for stone disintegration in NPL: dielectric breakdown near the probe tip, shockwave induced by the spark discharge, and asymmetric collapse of bubbles. Experiments have been performed to correlate the proposed mechanisms with the damage patterns observed. Comparison between micro-CT images of the damage initiation sites and COMSOL simulation of the stress field in the stone indicates that the observed cracks are most likely to be produced by the locally intensified tensile stresses produced by surface acoustic waves (SAW) generated by the incidence of the spark-generated, spherically divergent shockwave on the proximal surface of the stone, and their interactions with bulk acoustic waves (P or S) upon reflection at stone boundaries. Dielectric breakdown may contribute to crater formation. However, the contribution of cavitation to stone fragmentation in NPL appears to be minimal.
Shear waves in pressurized poroelastic media
Authors: Nazari Navid , Barbone Paul E.
Published: June 2017

Shear wave elastography measures shear wave speed in soft tissues for diagnostic purposes. In Rotemberg et al. [J. Biomech. 46(11), (2013), pp. 1875-1881] and Rotemberg et al. [Phys. Med. Biol. 57(2), (2012), pp. 329-341], shear wave speed measurements were shown to depend on prestrain, but not necessarily prestress, in a perfused canine liver. We model this phenomenon by examining incremental waves in a pressurized poroelastic medium with incompressible phases. For a poroelastic material with strain energy function W, which due to pressurization undergoes a volume expansion of Δ, we find the following general expression for the shear wave speed: c2/c02=(W1(Δ) + W2(Δ) Δ2/3)/Δ2/3 (W1(1) + W2(1)). Here, c0 is the shear wave speed in the unpressurized material, Wj = ∂ W/∂ Ij, and Ij is an invariant of the Cauchy-Green strain tensor. We also find important restrictions on the form of the strain energy function, which are typically not satisfied by strain energy functions commonly assumed for soft tissues.
Capacitive micromachined ultrasound transducers for acoustic anemometry on Mars
Authors: Ligonde Gardy K. , Torres Daniela A. , Abboud Eric F. , Sung Wang-Kyung , Vlahakis James , Banfield Donald J. , White Robert D.
Published: June 2017

An acoustic anemometer is under development for measuring wind speeds on Mars. Acoustic anemometry allows simultaneous measurement of wind speed and the speed of sound by measuring the acoustic time of flight in the forward and reverse directions. Acoustic anemometry avoids some sources of measurement error that plague other techniques for measuring winds in planetary atmospheres, such as hot wire measurements, or laser based tracking of scattered light from dust. The particular focus of this paper is the ultrasound transducers needed for the instrument. Capacitive micromachined ultrasound transducers (CMUT) fabricated at Tufts University have previously been described for atmospheric pressure operation (ASA Fall Meeting 2012). In this work, the transducers have been modified and tested under low pressure conditions similar to the atmospheric conditions expected on Mars (4.5 Torr). We describe a comparison between the modeled and measured transducer frequency response. The CMUT resonant frequency decreased from 204 kHz at 760 Torr to 116 kHz at 1 Torr. This is predicted by the models. The quality factor increased with decreasing pressure as expected, and is accurately modeled above 50 Torr. However, at pressures below 50 Torr, unmodeled damping mechanisms dominate acoustic losses, and a purely acoustic model underpredicts damping.
Characterization of free field radiation in brass instrument horns under swept sine excitation using a linear microphone array
Authors: López-Carromero Amaya , Kemp Jonathan A. , Campbell D. Murray
Published: June 2017

A linear array with 23 microphones is used to scan a planar section of the sound field radiated into an anechoic environment by a range of brass instruments excited by a sinusoidal sine sweep. The planar section contains the symmetry axis of the bell and covers a rectangular area of 0.9 by 0.6 metres, starting at the plane of the bell and extending away from it along the longest side. The linear microphone array is perpendicular to the symmetry axis and is stepped along the axis. The resulting matrix of signals is processed to separate the linear and non-linear parts of the response; the three-dimensional pressure distribution in the sound field is deduced on the assumption that the field is cylindrically symmetric. This data then allows the visualization and further analysis of the frequency dependence of radiated wave fronts in brass instrument bells. Comparison is drawn between the observations and the predictions of several popular radiation models.
Non-invasive measurement of acoustic coupling between the clarinet bore and its player’s vocal tract
Authors: Lulich Steven M.
Published: June 2017

As acoustically coupled resonators, the bore of a clarinet or other woodwind instrument and the vocal tract of the player interact in ways that affect timbre and pitch. Pitch in particular is strongly dependent on vocal tract acoustics when the bore-tract coupling is strong, such as when a tract impedance maximum is close in frequency and amplitude to a bore impedance maximum. Direct investigation of bore-tract coupling requires invasive measurement of bore and tract input acoustic pressures (or impedances), and one particular technique makes us of the ratio of these pressures (in the frequency domain, Pt/Pb) at harmonics of the reed vibration fundamental frequency. A non-invasive, model-based approach to investigating bore-tract coupling has been developed, which depends on a free-field microphone recording the sound produced by the instrument (P1), and an accelerometer placed against the skin of the neck recording skin vibrations (P2) related to intra-tract acoustic pressures. An additional, model-based calibration step is required. The ratio of these two signals (in the frequency domain, P2/P1) following calibration is qualitatively similar to the ratio Pt/Pb, and approaches quantitative identity as the model-based calibration step improves.
Stepwise regimes in elephant trumpet calls: Similarities with brass instrument behavior
Authors: Gilbert Joël , Stoeger Angela , Charlton Benjamin , Reby David
Published: June 2017

Trumpet calls are very loud voiced signals given by highly aroused elephants, and appear to be produced by a forceful expulsion of air through the trunk. Beyond their characteristic “brassy quality” previously attributed to shockwave formation, some trumpet calls are also characterized by stepwise fundamental frequency increase and decrease. Here we used spectral analysis to investigate the frequency composition of trumpet calls from one Asian and one African elephant. We found that the frequency interval between the steps were consistent with resonances expected in the exceptionally long elephant vocal tract. Such stepwise regimes are commonly observed in brass instruments as self-sustained oscillations transiently align on the bore’s resonance frequencies during arpeggios. We suggest that this production mechanism may constitute a rare example of source-filter interaction (where the filter properties affect the behavior of the source) in the vocal system of a terrestrial mammal. These preliminary observations also emphasize how the generalization of musical acoustic models can provide useful insight into the production of animal vocal signals.
Embrace for impact: Formant reconstruction in sudden pitch raise while singing
Authors: Long Chi-Yang , Lai Yuwen
Published: June 2017

Professional singers are trained to maintain vocal configuration by suppressing laryngeal elevation when singing high notes. The present study investigates the organization of vocal filter in sudden pitch raise condition by examining the corresponding acoustic correlates. More specifically, we are interested in whether this phenomenon may have differential effect on vowels with different height. In the experiment, high and low vowels were embedded in a nonsense Mandarin carrier sentence “kuai-lai-kuai-lai___yi-po” with C4E4G4E4___D4D4 pitch contour. Thirty amateur singers were recorded singing the sentence in four melodic conditions with the pitch intervals between the preceding syllable /lai/ to target word manipulated. The conditions are Micro (E4 to D4), Macro (E4 to D5), all High (every word sung in D5) and Null (only the last three words sung in D5-D5D5 contour). The results show that high pitch singing (Macro, High, and Null) indeed induces formant reconstruction when compared to Micro and the effect is markedly stronger in Macro. Furthermore, high vowel are more susceptible than low vowel and undergoes greater degree of formant reconstruction. The results provide acoustic grounding for the possible interplay between diction and pitch contour.
On characteristics of Trot singer Bae Ho’s singing voice
Authors: Park Sang Bum , Bae Myungjin
Published: June 2017

In Korea, the trot began shaping its own style in the 1960s. Then, later in the 1970s, it became more specialized having four-fourths beat rhythm of fox-trot, and the Korean style has been finally established with a strong beat and a unique chopping technique. Although there are many trot singers in Korea, the singer Bae Ho was very special in using the heavy bass accompaniment which was later frequently used by other pop singers. The singing voice of Bae Ho gives us the feeling of special softness and appealingness. In addition, his vocalization features the addition of a deep vibe to the song, so that the listeners feel sympathetic and comfortable. This study compares the singing voice of Bae Ho to that of his mimic singers by examining acoustic characteristics of their voices including amplitude, frequency and duration. The acoustic analysis proved that the singing voice of Bae Ho is clearer and has longer duration of vibration in the bass section than that of mimic singers. Bae Ho has a natural talent in expressing the bass part as well as in the midrange part without changing the tone of his voice, while the mimic singers reveal many unnatural connections between measures.
Community tolerance level as a paradigmatic shift in development of dosage-response relationships
Authors: Fidell Sanford
Published: June 2017

Dosage-response functions relating the prevalence of a consequential degree of annoyance in communities to cumulative exposure to transportation noise have typically been derived by correlational methods. Such non-causal analyses fit a curve to a set of field observations of annoyance prevalence rates in multiple communities, typically by means of univariate logistic regression. The resulting curve passes through the centroid of a cloud of data points, but provides no insight into the great variability among communities in annoyance prevalence rates at similar noise exposure levels. Community Tolerance Level analysis partitions annoyance into acoustic and non-acoustic components. This approach is a normative (that is, causal and prescriptive) one that fits data sets to an a priori function in order to estimate a second parameter. The second parameter is the deviation from the assumed (effective loudness) growth function, expressed in decibel-denominated units as the level of cumulative noise exposure at which half of a community is predicted to be highly annoyed by transportation noise. CTL analyses of community response to transportation noise thus permit direct quantification not only of the growth of annoyance with noise exposure, but also of the aggregate effect of all non-acoustic influences on annoyance prevalence rates.