bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct measurement of the dynamic range for rectangular speech passbands, from threshold to rollover
Authors: Bashford James A. , Warren Richard
Published: October 2015

Measurement of passband intelligibility can be confounded by appreciable contributions from transition bands under filtering conditions conventionally considered steep. Eliminating appreciable contributions outside of speech passbands can require slopes of several thousand dB/octave [Warren et al., JASA. 115, 1292-1295]. By employing effectively rectangular passbands, it is possible to determine their intrinsic intelligibilities, and also their dynamic ranges as determined by their threshold amplitudes and their decrease in intelligibility at high levels (“rollover”). Uncontaminated measures of these limits were obtained in the present study using 1-octave passbands (Experiment 1) and 1/3-octave passbands (Experiment 2) using rectangular speech bands (4800 dB/octave slopes) that spanned the frequency range from 0.25 to 8.0 kHz. Results obtained for the bands presented singly and in pairs, at levels ranging from threshold to 80 dB SL, indicate that [1] the speech dynamic range substantially exceeds 30 dB across most of the spectrum, and that [2] intelligibility rollover occurs at relatively low levels, exceeding approximately 70 dB. The use of rectangular speech bands for clinical assessment will be discussed. [Research supported by NIH.]
Maintaining speech intelligibility at 100 dB using arrays of subcritical width rectangular bands
Authors: Warren Richard , Lenz Peter
Published: October 2015

The Speech Intelligibility Index employs 16 contiguous 1/3-octave bands that sample the importance of frequencies across the speech spectrum. The present study employed the same Center Frequencies (CFs) using “Everyday Speech” sentences, but reduced the original 1/3-octaves having 26% bandwidths to 4% effectively rectangular bands (4800 dB/octave slopes). The resulting array of 16 subcritical-width bands had an intelligibility of 96% when heard at 60 dB despite having less than 16% of the 1/3-octave bandwidths. But, increasing the amplitude to 100 dB produced a decrease in intelligibility (“rollover”) to 86%. In a parallel experiment, when the sixteen bands had a bandwidth of 40 Hz for each of their CFs, the intelligibility was 95% at 60 dB and decreased to 91% at 100 dB. But when a “chimera” or hybrid was created with a width of 40 Hz for all CFs from 0.25 kHz to 1 kHz, and a width of 4% for CFs from 1 kHz (bandwidth of 40 Hz) to 8 kHz (bandwidth of 320 Hz), then intelligibility was 99% at 60 dB, and 97% at 100 dB. Hybrids of this type may be of use in hearing aid design. [Research supported by NIH.]
Correlation trends in Naval Surface Warfare Center Panama City Division’s database of simulated and collected target scattering responses focused on automated target recognition
Authors: Malphurs David E. , Lim Raymond , Lee Kwang , Sammelmann Gary S.
Published: October 2015

In recent years, NSWC PCD has assembled a database of sonar scattering responses encompassing a variety of objects including UXO, cylindrical shapes, and other clutter-type objects deployed on underwater sand and mud sediments and inspected over a large range of aspect angles and frequencies. Data available on these objects consist of a simulated component generated with 3D finite element calculations coupled to a fast Helmholtz-equation-based propagation scheme, a well-controlled experimental component collected in NSWC PCD’s pond facilities, and a component of measurements in realistic underwater environments off Panama City, FL (TREX13 and BayEX14). The goal is to use the database to test schemes for automating reliable separation of these objects into desired classes. Here, we report trends observed in an on-going correlation analysis of the database projected onto the target aspect vs frequency plane to clarify the roles of the environment, the data collection process, and target characteristics in identifying suitable phenomena useful for classification. [Work supported by ONR and SERDP.]
Prediction of localization error in generating a focused source
Authors: Song Min-Ho , Choi Jung-Woo , Kim Yang-Hann
Published: October 2015

This paper proposes a method of predicting human localization error for a focused source. A focused source is a virtual source located in between of a loudspeaker array and a listener. However, generation of the focused source cannot avoid the artifact due to causality, listeners always perceive pre-echoes before the desired sound. Since the human hearing system is sensitive to a preceding waves, it can lead a listener to perceive a virtual source in undesired direction. Because the repeating pre-echoes are observed for ineligibly long interval (∼100 ms), it is not clear to distinguish timbral distortions and echoes from the localization error due to the summing localization of the human auditory system. Therefore, a suppression condition was defined from the precedence effect to separate the localization error from timbral distortions. After applying the suppression condition, the energy vector model was used to quantify the localization error. Combining the suppression condition and the energy vector model, localization error in horizontal plane for each listening spot considering positions of focusing point, array shape, driving solutions, spatial sampling, and truncation can be predicted. The examples show that the prediction method clearly holds up with focused source observations reported from relevant literature.
Directional characteristics of musical instruments, and interactions with performance spaces
Authors: Meyer Jürgen , Hansen Uwe J.
Published: October 2015

The seminal work: “Acoustics and the,Performance of Music” by Jürgen Meyer, translated by Uwe Hansen, includes a summary of decades of groundbreaking measurements in the acoustics laboratory of the PtB (Physikalisch-technische Bundesanstalt—Physical and Technical Federal Institution—Germany's Bureau of Standards). Interactions with faculty and students of the School of Music in Detmold, Germany, as well as with numerous audio engineers and performers have contributed to an understanding of the significance of these data. Directional characteristics of a number of musical instruments will be reviewed and discussed, as well as their effects on seating arrangement in the orchestra and interactions with performance spaces.
Sound radiation properties of musical instruments and their importance for performance spaces, room acoustics measurements or simulations, and three-dimensional audio applications
Authors: Caussé René E. , Noisternig Markus , Wausfel Olivier
Published: October 2015

The directionality of the radiated sound is very specific to each musical instrument. The underlying radiation mechanisms may, for instance, depend on the structure of the vibrating body (e.g., string and percussion instruments) or on the spatial distribution of the opening holes (e.g., bells and open finger holes for wind instruments). A good knowledge of the radiation pattern of instruments is essential for many applications, such as orchestration, room acoustics, microphone techniques for live sound and recording, and virtual acoustics. In the first part, we will review previous works on sound source radiation measurement and analysis, discuss the underlying acoustic principles, and try to identify common mechanisms of radiation in musical instruments. In the second part, we will illustrate various projects undertaken at IRCAM and dedicated to the measurement and modeling of the directivity of instruments, to the objective and perceptual characterization of room acoustics, and to the real-time synthesis of virtual source radiation for musical performances. For this latter, several approaches are discussed according to the underlying physical formalisms and associated electroacoustic setups (e.g., spherical loudspeaker arrays, wave field synthesis).
Challenges of musical instrument reproduction including directivity
Authors: Zotter Franz , Frank Matthias
Published: October 2015

Reproduction of music from a solo instrument or singers by a single loudspeakers can suffer from lack of presence and liveliness if the directivity is missing. In particular, natural solo music contains the effects of a time-varying directivity with particularities in the directivity index, shape, yielding different coloration of diffuse reverb, early reflection, and direct sound. Focusing on the root of technical realization, it would be desirable to capture and reproduce a recording of an instrument played within a spherically surrounding microphone array in an anechoic chamber. This contribution reviews fundamentals (the soap bubble model) and technical solutions for this particular recording and playback problem, utilizing surrounding spherical microphone arrays and compact spherical loudspeaker arrays, also an application in which a trombone with directivity had been transmitted live from Graz to Paris. However, these solutions need to be carefully used as they hide some essential challenges: Surrounding spherical arrays suffer from the acoustical centering problem and the comb-filtering artifact it creates, and compact spherical loudspeaker arrays for directivity synthesis are subject to a trade off between bandwidth and spatial resolution against temporal resolution. For some of these challenges, alternative approaches will be addressed.
High-resolution measurements of speech directivity
Authors: Whiting Jennifer K. , Leishman Timothy W. , Bodon K. J.
Published: October 2015

Directivity patterns of loudspeakers are often included in room acoustics simulation packages, but those of live sources are less common, partly because of the scarcity of reliable high-resolution data. In recent years, researchers at Brigham Young University have explored high-resolution directivities of musical instruments. Their methods have now been adapted to directivity measurements of live speech. The approach uses a semicircular array of 37 microphones spaced with five-degree polar-angle increments. A subject sits on a computer-controlled rotating chair with his or her mouth aligned at the axis of rotation and circular center of the microphone array. He or she repeats a phonetically balanced passage at each of 72 five-degree azimuthal-angle increments. Transfer functions between a reference microphone signal from the rotating reference frame and every array microphone signal enable computations of high-resolution frequency-dependent directivity balloons. Associated coherence functions allow judgment of frequencies for which directivity data can be trusted. This presentation discusses the results of these measurements and compares them to previous measurements of speech and singing-voice directivities. Animations of directivity balloons over frequency show a more complete picture of speech directivity than has been previously published.
Measuring quiet time in neonatal intensive care units
Authors: Weber Jonathan , Ryherd Erica E. , Darcy Mahoney Ashley , Rolfes Myra , Cooper Heather , Cherven Brooke
Published: October 2015

The soundscape of critical care wards such as Neonatal Intensive Care Units (NICUs) are of particular concern due to the extremely sensitive nature of the patient population. NICUs must be conducive to providing care that enables infants to adapt to the extrauterine world without undue environmental stressors. Although the American Academy of Pediatrics (AAP) and others have set recommended noise limits in the NICU, studies consistently show units exceeding these standards. More nuanced aspects of NICU noise, such as source type, spectral content, fluctuations, and speech intelligibility are also of concern. A long-term study is being conducted that aims to improve NICU soundscapes, including measuring the impact of a Quiet Time (QT) evidence-based practice change. The study is a unique collaboration between engineering, architecture, nursing, and medicine. Detailed acoustic measurements were taken over a 18-month period to assess the soundscape in pre-QT, short-, mid-, and long-term post QT implementation periods. The study methodologies and results will be discussed, including considerations for the complexities of measuring sound fields in NICUs. Results are being used to identify and evaluate soundscape interventions and therefore advance understanding of how to design, measure, and implement healthy NICU soundscapes.
Three-dimensional sonar beam control of FM echolocating bats during natural foraging revealed by large scale microphone array system
Authors: Motoi Kazuya , Sumiya Miwa , Fukui Dai , Kobayashi Kohta I. , Fujioka Emyo , Hiryu Shizuko
Published: October 2015

In this study, 3-D flight paths and directivity pattern of the sounds emitted by Pipistrellus abramus during natural foraging were measured by a large scale microphone array system. The results show that the bats approached prey with covering the direction of them within their sonar beam. The means of horizontal and vertical beam widths were 49 deg and 46 deg, respectively. Just before capturing prey, the bats decreased the terminal frequency (TF) of the pulse. Simultaneously, the beam widths were expanded to 64 deg (horizontal) and 57 deg (vertical). We assumed a circular piston model to estimate how much the beam width was changed by decreasing the frequency of emitted pulse. It was found that the observed expansion of the beam width was smaller than those of theoretical estimations. This suggests that the bats decrease the TF of pulse for compensating their beam width narrowed by taking a large bite for the prey. We also measured echolocation calls and flight behavior of Myotis macrodactylus during natural foraging. M. macrodactylus uses FM echolocation pulse which is similar to P. abramus, but they forage for prey above the water surface. We compare echolocation strategies between two FM bats with different foraging habitat.
Pulsed sounds produced by amazon river dolphin (Inia geoffrensis) in the Brazilian Amazon: Comparison between two water turbidity conditions
Authors: Melo Jéssica F. , Amorim Thiago , Andriolo Artur
Published: October 2015

Pulsed sounds produced by the amazon river dolphin compose their acoustic repertoire, and possibly have communicative function. We analyzed the acoustic behavior of amazon river dolphin under two water turbidity conditions in the Brazilian Amazon. Data were collected during three days when animals exhibited foraging behavior. The sounds were classified according to spectrographic visual characteristics. The acoustic parameters were obtained for each category. The Wilcoxon test was applied to compare the acoustic parameters between black water (BW) and white water (WW). In a total of 525.47 minutes of recording in Juami-Japurá Ecological Conservation Unit, 70.6% was in black water and 29.4% in white water. We found seven types (A, B, C, D, E, F, and G) of pulsed sounds. Types A, C, D and F were found exclusively in black water, while B (BW 46.4%; WW 53.6%), C (BW 80.8%; WW 19.2%) and G (BW 50.7%; WW 49.3%) were present in both conditions. The type B showed significant differences (p < 0.01) in low frequency, center frequency and peak frequency. Types C and G showed no difference in the parameters between the waters. This result indicates that water turbidity plays a role on the acoustic behavior of amazon river dolphin.
Inversion of ship-noise scalar and vector fields to characterize sediments: A critical review of experimental results (2007–2014)
Authors: Hermand Jean-Pierre
Published: October 2015

During geophysical and ecosystem surveys in Mediterranean and Atlantic shallow waters, research vessels, fishing boats, and passenger ferries were used as acoustic sources of opportunity to characterize bottom sediments of different types including mud, fluid mud, and sand. The ships sailed a straight course at constant engine speed while a compact vertical array of pressure or pressure-gradient sensors, deployed from a small boat, sampled the generated noise field over a broad frequency range. Different acoustic observables were investigated that do not depend on the knowledge of ship noise characteristics to mitigate the impact of such uncertainty. For sole pressure measurement, extraction and parameterization of striation structures in range-frequency spectrograms at different receiver depths allow to determine effectively compression wave speed and thickness of a sediment layer as compared to a reference. For additional pressure gradient measurement, vertical impedances are estimated at different depths whose range and frequency dependence are highly sensitive to bottom properties and, in particular, density. Global optimization via genetic algorithm and sequential Bayesian estimation via particle filtering maximize the degree of similarity between predicted and measured impedance data. The paper will critically review the experimental results and compare them with ground truth data. [Work supported by ONR, FNRS-CNPq, WBI-CAPES, PREFACE project EC DG Env FP7.]
Experimental and computational multi-port characterization of a circular orifice plate
Authors: Sack Stefan , Åbom Mats
Published: October 2015

The generation and scattering behavior of fluid machines in duct systems is of great interest to minimize sound emission, for instance of air condition systems. Such systems may be described as linear, time-invariant multi-port networks containing passive elements, that scatter existing sound fields and active elements, that emit noise themselves. The aim of any multi-port analysis is to determine the direction-dependent transmission and reflection coefficients for the propagating wave modes and the sound generation. This parameters may be ascertained either numerically or experimentally. In a first step, external sound fields dominating the source are applied to determine the system scattering. In a second step, the source strength can be computed. Once these characteristic data are determined for all elements of interest, the sound scattering and emission of every considerable combination of multi-ports can be calculated easily. This paper shows an experimental study as well as a numerical approach to determine both, the passive and the active characterization of an orifice plate in a circular duct in presence of higher order acoustic modes. An enhanced measurement procedure is presented, and the results of this procedure are compared with data extracted from a full compressible DDES flow-computation.
Finite element method assisted development of an analytic model to describe the acoustic response of tee-junctions
Authors: Fries Dan , Scarborough David E.
Published: October 2015

Tee-junctions are a central element of almost any duct system. The acoustics of such are altered by the transversal branch defining the tee. Resulting phenomena have been studied experimentally, numerically and analytically in the past. However, a simple practical tool for prediction and fundamental understanding is still missing. Applying the Finite Element Method, this work attempted to analyze the tee-junction’s behavior with higher-order methods. To this end the commercial software COMSOL-Multiphysics was used. Thereafter, a low-order plane wave network model was developed and compared with simulation results. An error analysis of the power transmission coefficient computed by the model and the FEM simulation showed the limits of this low-order approximation. Thus, a guideline is provided for when the plane wave approximation delivers meaningful results. Moreover, it allowed for adjustments to the model increasing the model’s accuracy, using a semi-empirical expression for a frequency dependent length correction of the side-branch. This had been predicted by other authors but never given explicitly. For side branches longer than two main-duct diameters and a thickness equal to or smaller than the main duct, the model gives good results up to 85% of cut-on of the first higher order mode. The proposed model can easily be implemented to estimate the characteristic quantities of a tee-junction.
The effects of military training vibration on rock art
Authors: Lavallee Timothy , Loubser Jannie
Published: October 2015

This presentation will provide an overview of potential impacts of vibration due to military training on Native American rock art. Military training is often conducted in areas near culturally sensitive landmarks or structures, and information regarding the effects of vibration on these types of structures is limited. An extensive literature review was conducted to determine the current state of information regarding vibration effects on rock art and other cultural resources. The condition of rock art can vary from the extremely stable to fragile; and based on the existing studies, thresholds for effects were defined in term of stability class for different rock art structures. Vibrations and peak sound levels from maneuver and live fire training activities were estimated and compared to these effects thresholds. Both airborne and groundborne vibrations decreased with distance and at some point attenuate below the threshold of adverse effects. Critical distances for effects were estimated for a variety of training activities—including demolition activities, ground maneuvers, mortar fire, and rotorcraft operations. Results will be provided in both peak particle velocity and peak sound levels. These results as well as potential best management practices will be discussed.
Noise control within building water supply lines
Authors: Gruber Elliott , Cunefare Kenneth
Published: October 2015

Successful treatment of fluid-borne noise in a building’s plumbing system reduces noise propagation throughout the building, which improves occupant comfort and extends component lifetimes. Circulation pumps and quick-closing valves contribute to noise in water systems. Pump noise is generally untreated. Quick-closing valves m may cause water hammer, which can be treated with a water hammer arrestor (WHA). Common WHA’s functions by adding a compliant gaseous volume to the system; the gas volume is sealed from the system by a free piston. Control of both water-borne noise and water hammer may be achieved by a flow-through device integrating a compliant, voided polymer. The performance of current WHAs diminish over time as (1) mineral deposits degrade sealing effectiveness and (2) the gas permeates the seals; a voided polymer WHA will not suffer from these drawbacks. Prior work has demonstrated that a voided polymer is an effective source of compliance for noise control in oil systems at the anticipated pressure and temperature range of water systems. Furthermore, the acoustic impedance of oil is similar to water. Basic modeling and performance data for a prototype device will be presented.
Top-down influences in perception with spectrally degraded resynthesized natural speech
Authors: Smart Jane , Frisch Stefan
Published: October 2015

Lexical processes can influence perception of ambiguous phonemes (e.g., Ganong, 1980). To date, research has focused on these influences in quiet conditions with stimuli that have not been degraded. This project examines the interplay between lexical and acoustic information in speech perception, with stimuli in non-degraded and spectrally degraded conditions. Continua of /t, k/ onsets were developed by wavelet resynthesis of natural speech using TandemSTRAIGHT software, concatenated to the vowel × coda portion of words/nonwords, and distorted using AngelSim (TigerCIS) vocoding software. Normal hearing adult participants identified the onset phonemes in non-degraded and spectrally degraded conditions. Identification functions and the effects of lexical status in phoneme perception with spectrally degraded stimuli will be discussed.
Recent advancements in massive multi-channel auralization
Authors: Ahrens Jens , Wierstorf Hagen
Published: October 2015

Massive multi-channel auralization approaches like Wave Field Synthesis and Higher Order Ambisonics experienced a pronounced hype in the late 2000s during which the primary research goal was maximizing the physical accuracy of the synthetic sound fields that they create. The hype eventually faded as the achievable advancements turned out to be limited due to fundamental restrictions. Though, activities are still being pursued in the domain with the focus shifted towards perception of synthetic sound fields. This talk gives an overview over current activities, which aim at understanding localization, timbre, and spatial impression in general. The results show that localization performance in synthetic sound fields is close to the performance in real sound fields. Timbre and spatial impression exhibit impairments that are directly linked to the physical limitations of the employed systems. Promising options for improvements regarding the synthesis of artificial reverberation are discussed.
Worship space acoustics: Three decades of design
Authors: Tikriti Walid
Published: October 2015

The presentation discusses the acoustics and noise control design for new construction and existing worship space renovation and the challenges during the design stage. The first project is an addition of a chapel to an existing church. Treating the hard surfaces on the walls and ceiling proved challenging due to the historic nature of the building. The second project is an addition of a 1800 sq. ft. multipurpose room with a full glass wall. The Glory Be Hall space is intended to provide an acoustically pleasant space for various programs. The third project is a new construction of a 550 seat worship space. The acoustics design focused on achieving a balance between the amplified sound system, the background noise level from the mechanical equipment, the noise isolation from adjacent spaces including nursery and public spaces.
Non-invasive thrombolysis using histotripsy beyond the “intrinsic” threshold (microtripsy)
Authors: Zhang Xi , Gurm Hitinder , Owens Gabe , Xu Zhen
Published: October 2015

Histotripsy has been demonstrated as a non-invasive, drug-free, image-guided thrombolysis method using cavitation alone. Microtripsy is a new histotripsy approach, where cavitation is generated using 1-cycle ultrasound pulses with negative pressure exceeding a threshold intrinsic to the medium. We hypothesize that, using microtripsy, cavitation can be generated entirely within the vessel lumen, without contacting the vessel wall. Microtripsy was used to create a flow channel through a clot in a vessel-mimicking phantom by scanning the therapy focus through the clot at a pre-set interval. Different scan intervals, doses, and strategies (single focus vs. electrical-steered multi-foci) were tested in both unretracted and retracted clots. The flow channel size, thrombolysis rate, and clot debris particle sizes were measured. A cavitation cloud and flow channel was successfully generated and completely confined within the 6.5 mm-diameter vessel lumen through unretracted and retracted clots. A 1-4 mm channel was created in unretracted clots, at thrombolysis rate of 3.3 min/cm. Using an electrical-steered multi-foci method, a 1–2.5 mm channel was generated through retracted clots, at thrombolysis rate of 5.5 min/cm. The debris particles generated were no greater than 150 μm. The results show the potential of microtripsy for precise and effective clot recanalization, minimizing risks of vessel damage and embolism.
Microscale interactions between ultrasound stimulated microbubbles and the fibrin networks of clots
Authors: Goertz David , Acconcia Christopher , Leung Ben
Published: October 2015

While the concept of microbubble mediated sonothrombolysis is now well established, a detailed mechanistic understanding of this process remains both elusive as well as necessary in order to facilitate the development of improved exposure methods. As lytic effects may ultimately arise from microscale bubble-clot interactions, we have employed high-speed microscopy and two-photon microscopy to examine these interactions first in (transparent, fluorescently tagged) fibrin clots, and then in blood clots. Bubble “population” studies in fibrin clots show the prominent role of primary and secondary radiation forces: bubbles are first directed toward the clot boundary, where their concentrations increase and interactions such as clustering and coalescence occur frequently. A subset of bubbles penetrate into the clots, disrupting the fibrin network structure along their paths. Once initiated, the resulting tunnels act in subsequent exposures as conduits for bubbles to enter and access deeper points within the clot. Using optical tweezers, individual bubble experiments reveal that bubble entry into the clots, along with the accompanying network damage and fluid uptake, are a function of the network pore size, bubble size, and the exposure scheme. With blood clots, the erosion surface evolves in a complex manner, involving the ejection of erythrocytes and the development and progression of a cell depleted fibrin network zone. The characteristics of the erosion front are highly dependent on exposure conditions.
Ultrasound-enhanced thrombolysis: Mechanistic observations
Authors: de Saint Victor Marie , Carugo Dario , Coussios Constantin , Stride Eleanor P.
Published: October 2015

Ultrasound and microbubbles have been widely demonstrated to accelerate the breakdown of blood clots, but the mechanisms of treatment require further investigation. In particular, there is a need to clarify the effect on the fibrin matrix—the insoluble polymer mesh that determines a clot’s integrity and mechanical properties. The objective of this in vitro study was to observe in real-time the mechanisms of microbubble-enhanced sonothrombolysis at the microscale. Fluorescently labeled porcine plasma clots were prepared on a glass coverslip and exposed to different types of microbubbles with or without the fibrinolytic agent recombinant tissue plasminogen activator. A 1 mm thick piezoelectric element was coupled with the glass substrate and driven at the resonant frequency of the system (1.9 MHz), with a duty cycle of 5% and a 0.1 Hz pulse repetition frequency. The acoustic field within the clot was characterized using a fiber optic hydrophone. Changes in the fiber network were monitored for 30 min by confocal microscopy.
ANSI/ASA S1.20-2012, “Procedures for Calibration of Underwater Electroacoustic Transducers,” Revision Details
Authors: Drake Robert
Published: October 2015

The ANSI/ASA S1.20-2012 standard, “Procedures for Calibration of Underwater Electroacoustic Transducers,” was released in February 2012. It is a revision of American National Standard S1.20-1988 (R2003). An overview of the content of this standard inclusive of the typical primary and secondary open water procedures for determining the measurable characteristics of free-field receive voltage sensitivity and transmitting responses are examined along with highlights of materials that are new to the 2012 revision. In this later category, this presentation provides overview information contained in the S1.20-2012 related to correction factor application (with an emphasis on extension cable usage) and introductory material on measurement uncertainty analysis (along with the identification of common error sources). A cursory look at the informational annexes will also be addressed with an emphasis on the 2012 revision-specific ones related to medium correction factors, nonlinear effects including cavitation, and a standard-target method for calibrating active sonars.
Experimental investigation of nonlinear wave behavior in a tensegrity mast
Authors: Westland Joy , Piacsek Andrew A. , Zencak Peter
Published: October 2015

First described by Fuller and Snelson in the mid-twentieth century, tensegrity structures comprise a network of elements that alternately support compression (struts) and tension (cables). When the cable elements are pre-stressed, tensegrity structures maintain a stable form, regardless of orientation. If external forces are applied, the structure will deform both locally and globally, with the stress distributed throughout the structure. Removal of the external forces will result in the structure regaining its original shape. However, the deformation is not a result of elastic strains in the individual elements, but rather a reorientation of the elements, and the restoring force is nonlinear. To characterize the effect of this nonlinearity on dynamic behavior, a tensegrity mast was constructed consisting of 60 aluminum bars, each of length 11 cm; the total mast length is approximately one meter. A mechanical shaker mounted at one end is used to drive the mast into resonance, as well as to create longitudinal pulses. Frequency response measurements are consistent with a stiff nonlinearity and evidence is shown for harmonic generation during pulse propagation. The effect of pre-stress tension is also investigated and discussed.
Uncertainty calculations of pressure sensitivity of one inch microphones using pressure field method at the National Metrology Institute of Egypt
Authors: Ahmed Rabab S. , Shawky Hany A. , Youssef Rabab S. , El-Basheer Tarek M. , Mohamed Hatem K.
Published: October 2015

Primary calibration method is used by relatively few laboratories such as national calibration laboratories and few large automotive, space, or governmental organizations, which work at high technological level. The National Metrology Institute of Egypt (NIS) has developed a pressure calibration system that used for calibration of pressure sensitivities. In this study, we estimate the uncertainty of unknown one inch condenser microphone using two known references one inch condenser microphones according to international standard. IEC 61094-2009 gives more information's and details on the uncertainty calculations. In this method, a wide frequency range with a high accuracy and repeatability were achieved.
The scattering of sound by a buried obstacle in an extended reaction ground
Authors: Wang Yiming , Li Kai Ming
Published: October 2015

The boundary integral equation (BIE) method is widely used in outdoor sound scattering problems due to its computational efficiency when compared with the finite element method. The advantage of the BIE is apparent for the case when the scattering surface is much smaller than the computational domain of the problem. However, one of the major difficulties of the BIE formulation is the need to obtain the required Green functions for a sound source placed in the vicinity of the extended surface—both above and below the air/ground interface. There have been some recent developments where accurate and fast computations of these Green functions become available for use in the BIE formulation. This paper discusses some of these accurate asymptotic solutions and addresses the required steps to develop the BIE formulation. The computation of sound fields for the obstacle buried partially/totally in an extended reaction ground are presented.
Influence of source motion, wind, and temperature profiles on the effective impedance of an absorptive surface
Authors: Li Kai Ming , Tong Bao N.
Published: October 2015

This paper presents a theoretical study of the sound field due to a moving source placed above an absorptive surface in a stratified medium in the presence of wind and sound speed profiles. The current analysis starts with the general equations for an isentropic inviscid flow field. A monopole source is assumed to be traveling parallel to the absorptive surface at a constant speed. The standard Lorentz transform can be applied and the Fourier decomposition can be used to express the sound field in an integral form that is amenable to further mathematical treatments. Either the fast field computation or the method of steepest descent can be used to evaluate the integral. A two-dimensional formulation was considered initially, but it can subsequently be extended to three-dimensional flow fields. The effect of source motion, wind, and temperature profiles on the acoustic properties of the absorptive surfaces have been explored.
Statistical moments of impulse propagation through the atmosphere
Authors: Cain Jericho E. , Collier Sandra L. , Cheinet Sylvain , Ostashev Vladimir , Wilson D. K.
Published: October 2015

In order to localize and classify propagating impulsive signals, a theoretical model that incorporates effects due to atmospheric turbulence, ground impedance, wind speed, wind direction, and refraction is needed to guide the analysis of data measured with acoustic sensing systems. Recently, measurements with planar arrays were made that form a database of acoustic measurements of impulse sources propagated through various atmospheric conditions, ranges, and ground types. This paper presents analyses of the statistical moments of this data for the purposes of comparison with recent theoretical models.
Characteristics of 40,000 calls to the National Hearing Test
Authors: Watson Charles S. , Kidd Gary R. , Preminger Jill E. , Miller James D. , Maki Daniel P. , Crowley Alex
Published: October 2015

The National Hearing Test (NHT) is a telephone-administered screen for hearing loss (Watson et al., J. Am. Acad. Audiol., 2012) that obtains thresholds for three-digit sequences in a noise background. The NHT has been validated by comparing threshold SNR values to mean pure-tone loss. During five weeks in 2014 the NHT was offered without charge to the general public. Over 40,000 calls were made after articles describing the test appeared in eight large-circulation and 19 smaller circulation newspapers, estimated to reach less than 10% of the US public. Among those who completed the test, 81% were estimated to have clinically significant loss in one or both ears. Call numbers suggested that 88% were made from landlines and the remainder from cell phones. Threshold SNRs for cell phones were about 1.0 dB higher than those for landline phones. Samples of the callers were later contacted through telephone and email surveys. Responses indicated a positive influence in terms of the likelihood of seeking further evaluation and obtaining hearing aids if advised to do so. [Research supported by the National Institute for Deafness and other Communication Disorders of the National Institutes of Health under award number 5R44DC009719.]
Effects of aging on auditory duration discrimination
Authors: Luckett Rachael , Goshorn Edward L.
Published: October 2015

The effects of aging on auditory processing are well documented. The involved anatomy includes the entire auditory pathway from peripheral to central mechanisms. Existing procedures to identify auditory processing disorders include a wide variety of signals with distortions or reduced redundancy in the temporal or frequency domains or the addition of noise. This project investigated the effects of aging on the ability to discriminate duration of a musical auditory signal. A musical signal was used to add temporally-variant acoustical information that would not be present in a pure tone. A digitized.wav piano note (fo = 422 Hz) with gradually decaying amplitude was edited in Sound Forge to produce two signals equal in spectrum, RMS amplitude, and VU level but differing durations (1000 and 800 ms). One hundred pairs of these musical signals were arranged in random order with half equal and half unequal in duration. The subject’s task was to designate same or different. Subjects ranged in age from 18 to 90 years. A regressions analysis revealed that age is a significant (p = .002) coefficient for predicting performance on a duration discrimination task. The findings suggest that duration discrimination tasks may contribute to identification of auditory processing disorders in adults.
The effects of acoustic variability on absolute pitch categorization: Evidence of contextual tuning
Authors: Van Hedger Stephen C. , Heald Shannon L. , Nusbaum Howard C.
Published: October 2015

Absolute pitch (AP) is defined as the ability to label or produce a musical note without the aid of a reference note. Despite the large amounts of acoustic variability encountered in music, AP listeners generally experience perceptual constancy for different exemplars within note categories (e.g., recognizing that a C played on a tuba belongs to the same category as a C played on a piccolo). The present studies investigate whether AP possessors are sensitive to context variability along acoustic dimensions that are not inherently linked to the typical definition of a note category. In a speeded target recognition task, AP participants heard a sequence of notes and pressed a button whenever they heard a designated target note. Within a trial the sequence of notes was either blocked according to note-irrelevant variation or contained a mix of different instruments (Experiment 1), amplitude levels (Experiment 2), or octaves (Experiment 3). Compared to the blocked trials, participants were significantly slower to respond in the mixed-instrument and mixed-octave trials, but not the mixed-amplitude trials. Importantly, this performance difference could not be solely attributed to initial performance differences between instruments, amplitudes, or octaves. These results suggest that AP note identification is contextually sensitive.
Cortical dynamics during spectrotemporal processing as indexed by directed functional connectivity
Authors: Eddins Ann C. , Eddins David A.
Published: October 2015

Neural processing in the cortex plays a key role in our ability to discriminate changes in acoustic features important for understanding speech. Converging evidence demonstrates functional asymmetries between hemispheres such that the left hemisphere (LH) typically shows greater sensitivity to temporal changes while the right hemisphere (RH) shows greater sensitivity to spectral change. Most human studies to date have evaluated static differences in hemispheric activation with little attention given to potential dynamic changes within and across hemispheres during stimulus processing. The present study quantifies changes in the cortical representation of spectral (0.5 and 2.0 cycles/octave), temporal (2, 8, 32, and 64 Hz), and spectro-temporal (combination of both) modulation frequency. Cortical event-related responses were measured using a 64-channel montage during a passive, continuous change-detection paradigm in young, normal-hearing listeners. Individual and group data were preprocessed and source-localized for all conditions, with regions of interest (ROI) defined on group data. To determine whether activity in one ROI dynamically influences another during stimulus processing, Granger causality modeling was used to estimate directed functional connectivity. Preliminary results show robust directional processing that may originate in one hemisphere (i.e., spectral processing in RH or temporal processing in LH) but dynamically engages cortical regions within and across hemispheres.
The test-retest reliability of measurement procedures on most comfortable loudness levels for pure-tones
Authors: Ho Cheng-Yu , Li Pei-Chun , Young Shuenn-Tsong
Published: October 2015

This study aimed to evaluate test-retest reliability of the forced-choice paired-comparison measurement procedures on most comfortable loudness levels (MCL) for pure-tones. Previous studies indicated that the MCL for pure-tones may be a range of level instead a fixed level, since the fixed-level MCL tends to be more inconsistent than a range of MCL. The ascending and descending measurement procedures were mostly used in the MCL for pure-tones, however the lower MCL obtained from ascending procedure, and higher MCL got from descending procedure, and since the low test-retest reliability of ascending and descending procedures, there are no well-established measurement procedures of MCL for pure-tones. The ascending and descending forced-choice procedure of MCL for speech might provide respectively 83% and 84% test-retest reliability, but the test-retest reliability measurement procedures of MCL for pure-tones have not been known. Therefore, this study proposed a new forced-choice paired-comparison measurement procedure on MCL for pure-tones, and evaluated the test-retest reliability of this proposed procedure. Normal hearing subjects are recruited to conduct this experiment, and evaluated by Pearson correlation. This experiment is ongoing, and the data collection would be finished before the presentation on the 170th Meeting of the Acoustical Society of America.
Model-based nonlinear guided wave approach for nondestructive evaluation in solid media
Authors: Cho Younho , Li Weibin
Published: October 2015

The measurement of acoustic nonlinear response of guided wave propagation has been explored as a promising tool for early detection of micro-damages. Considering the high sensitivity of the nonlinear ultrasonic approach and the great advantages of the guided wave techniques, the nonlinear guided wave techniques have drawn significant attention. Frequency tuning and mode selection play a critical role for practical nonlinear guided wave testing. Among all the guided wave modes, it is of particular interest to find the more suitable modes for the improvement of efficiency. Analytical expressions and experimental observations of second harmonic generation of guided waves in an isotropic plate, are presented in this talk. Nonlinear parameters of guided waves are newly derived as a function of wave mode, geometric information of waveguides and frequency. Nonlinear features of various phase matched modes are discussed for the comparison of efficiency of second harmonic generation. The experimental results are consistent with the theoretical predictions. This study shows that physically based feature selection is essential for efficient generation of second harmonic guided waves. The feasibility of Lamb waves mixing for nonlinear ultrasonic test is also discussed in this work.
Prosodic features of stance acts
Authors: Freeman Valerie
Published: October 2015

While textual aspects of stance (attitudes/opinions) have been well studied in conversation analysis and computational models, acoustic-phonetic properties have received less attention. Recent work (2014 and 2015) has found that variations in prosodic measures (speech rate, vowel duration, pitch, and intensity) are correlated with stance presence and strength in unscripted speech, and stances with different discourse functions may be distinguishable by the shapes of their pitch and intensity contours. Building on these early findings, this presentation investigates prosodic properties of various stance-act types in spontaneous conversation (e.g., opinion-offering and soliciting, (dis)agreement, persuasion, rapport-building). The dataset contains over 32,000 stressed vowels from content words spoken by 40 speakers drawn from an audio corpus of dyads engaged in collaborative tasks. Speaker-normalized vowel duration, pitch, and intensity are automatically extracted from time-aligned transcriptions that have been hand-annotated for stance strength, polarity, and act type. Results show that changes in the prosodic measures combine to distinguish several notable stance-act types, including: weak-positive agreement, rapport-building agreement, reluctance to accept a stance, stance-softening, and backchanneling. Pitch and intensity contours over vowel duration are particularly illustrative, suggesting a future avenue in examining contours over whole stance acts.