bluuebunny/crossref_metadata_2025 huggingface dataset:
High pressure focused ultrasound field characterization
Authors: Karaböce Baki , Şahin Ali , Bilgiç Eyüp , Sadıkoğlu Enver , Nur Süreyya
Published: November 2013

High intensity focused ultrasound (HIFU) transducers are novel and very attractive tools for cancer therapy. They produce very high pressure acoustic fields up to tens of MPa at the focus; thus, acoustic characterization of HIFU fields must be investigated in order to ensure the safe and effective use in clinical applications. A needle hydrophone has been used for HIFU transducer characterization in the newly designed home made system at TÜBİTAK UME (The Scientific and Technological Research Council of Turkey, the National Metrology Institute) Ultrasound laboratory. TÜBİTAK UME HIFU measurement system was controlled by a Labview based data translation program. The driving signal was generated by signal generation card and output from the hydrophone was fed directly into a DSO oscilloscope card. The controlling program executed a “capture-analyze-move” cycle, allowing a large number of measurements to be made. Field scanning measurements are made between 1 MPa, 2 MPa, and 3 MPa pressures. Theoretical model for the beams of periodic waves with an initially uniform amplitude distribution was also performed, based on the Khokhlov-Zabolotskaya-Kuznetsov equation. Numerical solutions were compared with the experimental data and found to be in agreement.
Energy harvesting from acoustic sources
Authors: Cunefare Kenneth
Published: November 2013

While energy harvesting from a variety of ambient sources (vibration, light, and wind) has been demonstrated and sensing and communication applications to exploit those sources have been developed, acoustic energy as an ambient source has not received much attention. The reason for this comes down to the basic physics of how much energy is available within an acoustic field. For airborne sounds, the energy density in sound fields that are perceived by humans to be quite loud (e.g., 80 to 160 dB, or ∼0.2 Pa to ~2 kPa) actually represent an extremely low available energy source. In consequence, means must be taken to intensify an acoustic response, for example, through resonance, but even so, available energy remains limited. The exception to this issue in airborne sounds is the sound field that exists inside of an operating jet aircraft engine. The situation is quite different, however, when one considers pumped and pressurized fluid systems, where acoustic pressure variations due to the operation of pumps and other devices may reach into the mega-Pascal (MPa) range. Energy harvesting from such a fluid-borne acoustic source is feasible for powering sensors and wireless communication systems and has been successfully demonstrated.
Data-driven prediction of peak sound levels at long range using sparse, ground-level meteorological measurements and a random forest
Authors: Valente Dan
Published: November 2013

Outdoor sound propagation is highly dependent upon meteorological conditions. While this, of course, is a trivial statement, predicting sound levels based on meteorology is not. This is especially true for signals that propagate many kilometers, as is the case for those generated by high-energy impulsive sources such as explosions and heavy weaponry; waves have ample opportunity for refraction by and scattering from local atmospheric features along the entire propagation path. The range of received blast levels at distances greater than 2 km can span nearly 50 dB, depending on weather conditions. Using a statistical learning method known as a Random Forest, we demonstrate the prediction of levels from simple meteorological measurements in the face of this extreme variability. With simple, spatially sparse meteorological data, the model can predict levels to within 3 dB at 2 km and 5 dB at 15 km. The results presented here suggest that as more data are acquired through continuous noise monitoring programs, physics-blind, data-driven statistical models have the potential to supplant computationally intensive propagation models for noise prediction. Caveats and cautions when using these types of machine learning methods will also be discussed.
Accurate quantification and delivery of thermal dose to cells in culture
Authors: Martin Elly , Shaw Adam , Faruqui Nilofar , Shaw Michael
Published: November 2013

HIFU treatments involve raising the temperature of target tissue above 60°C in short (~2 s) bursts. At higher temperatures, shorter times are required to induce a given deleterious effect: the Sapareto-Dewey thermal dose equation is often used to relate the time to produce a biological effect at one temperature to the time to produce equivalent effects at another. A heating chamber was developed to deliver controlled thermal doses to cells in culture under continual observation by differential interference contrast microscopy. The system comprised of a cell culture well and cover slip coated with a transparent electrode inserted into a microscope stage with electrical contacts. Thermal doses were delivered by applying programmed current-time profiles and using a PID controller to rapidly raise and maintain the temperature of the chamber above 37°C while monitoring with fine wire thermocouples. Initially, HeLa cells in monolayer culture were imaged before, during, and after heating. Visible changes in cell shape and adhesion began shortly after raising the temperature by 8°C and progressed during a heating period of 20 min, continuing for more than 12 h after the cells were returned to 37 °C. No such changes were observed in control cells. Results will be presented exploring the validity of the S-D relationship for shorter, higher temperature exposures.
Prediction of the reversibility of the ultrasound-induced blood-brain barrier opening using passive cavitation detection with magnetic resonance imaging validation
Authors: Sun Tao , Samiotaki Gesthimani , Konofagou Elisa E.
Published: November 2013

Various molecules have been shown to cross the blood-brain barrier (BBB) upon exposure to focused ultrasound combined with microbubbles and exhibit therapeutic effects. Real-time monitoring, thereof, remains one of the key elements before clinical translation of this technique. The dependence of acoustic emissions on the closing timelines of the BBB opening volume and its permeability was investigated under different pressures (0.30, 0.45, and 0.60 MPa) and microbubble sizes (diameters: 1–2, 4–5, or 6–8 μm). A 10-MHz passive cavitation detector was used to acquire cavitation signals during sonication at the mouse right hippocampus (n = 45). Contrast-enhanced dynamic and T1-weighted MR scans were performed immediately after sonication and up to 6 days thereafter. Contrast-enhanced volumes and diffusion rates of the contrast agent were quantified as indicators for the BBB opening. It was found that the stable cavitation dose increased with the number of days required for closing while it reached a plateau after day 4. However, the inertial cavitation dose exhibited an exponential increase with the duration of the opening. A linear correlation between the total cavitation dose and BBB opening days was found. Moreover, the volume and permeability indicator K trans were found to be both pressure- and bubble size-dependent. The dependence on the bubble-diameter and pressure allows us to predict and control the safety profile of this technique.
Microphone array exploratory study
Authors: Messier Marc
Published: November 2013

In the field of acoustic signal processing, one of the most popular areas of research is that of microphone arrays. As a small research project in this field, a microphone array system with adjustable polar response will be developed. It is worth noting that this submission is more a research proposal than an abstract. This research will take part as a means of combining coursework and research for courses in engineering acoustics and real-time digital signal processing at the University of Miami. Before any arrays are physically constructed or any code written on a DSP, simulations will be performed in Matlab to determine optimum array configurations and to analyze various DSP algorithms for adjusting polar responses. Then, using a Texas Instruments TMS320C6713 DSP on a DSK audio target board, and writing code in C, Assembly, and Matlab, physical tests will be conducted to analyze performance of design. A MEMS microphone model will likely be used for its small size and low cost. From there, results will be analyzed and further research in the area proposed.
A simple adaptive cardioid direction finding algorithm
Authors: Elko Gary W. , Meyer Jens
Published: November 2013

A simple direction-finding algorithm using three or four omnidirectional microphones is described. The algorithm is based on the minimization of the output power of a generally steerable cardioid microphone. It is shown that the algorithm can be reduced to running three independent single-tap LMS filters for the general 3D case and two independent single-tap LMS adaptive filters for the 2D (null constrained to lie in a plane). Results will also be shown for a 32-element spherical microphone array for sources corrupted with microphone self-noise and reverberation.
In situ evaluation of surround sound system performance
Authors: Benjamin Eric M. , Heller Aaron J. , Lopez-Lezcano Fernando
Published: November 2013

Surround sound systems are produced with the intention of reproducing the spatial aspects of sound, such as localization and envelopment. As part of his work on Ambisonics, Gerzon developed two metrics, the velocity and energy localization vectors, which are intended to predict the localization performance of a system. These are used during the design process to optimize the decoder that supplies signals to the loudspeaker array. At best, subjective listening tests are conducted on the finished system, but no objective assessments of the spatial qualities are made to verify that the realized performance correlates the predictions. In the present work, binaural recordings were made of a 3-D 24-loudspeaker installation at Stanford’s Bing Studio. Test signals were used to acquire the binaural impulse response of each loudspeaker in the array and of Ambisonic reproduction using the loudspeaker array. The measurements were repeated at several locations within the hall. Subsequent analysis calculated the ITDs and ILDs for all cases. Initial results from the analysis of the ITDs and ILDs for the center listening position show ITDs, which correspond very closely to what is expected in natural hearing, and ILDs, which are similar to natural hearing.
Network modeling of multiple-port transducers across multiple modes of vibration
Authors: Kuntzman Michael L. , Hewa-Kasakarage Nishshanka N. , Kim Donghwan , Hall Neal A.
Published: November 2013

A network modeling procedure is presented that is capable of modeling transducers across a broad frequency regime with multiple coupling ports. The model is based on modal superposition, and a separate network is crafted for each vibration mode of the device. Modal velocity, rather than a particular physical velocity on the vibrating transducer, is chosen as the flow variable in each network. Multiple ports are modeled with the use of multiple transformers in series. A procedure for performing system identification to complete the network parameters is also presented, which can be performed experimentally, analytically, or through use of a finite element model in the design stage. Application of the procedure to a multiple port piezoelectric microphone is presented.
Environment mapping and localization with an uncontrolled swarm of ultrasound sensor motes
Authors: Duisterwinkel Erik , Demi Libertario , Dubbelman Gijs , Talnishnikh Elena , Wörtche Heinrich J. , Bergmans Jan W.
Published: November 2013

A method is presented in which a (large) swarm of sensor motes perform simple ultrasonic ranging measurements. The method allows to localize the motes within the swarm, and at the same time, map the environment which the swarm has traversed. The motes float passively uncontrolled through the environment and do not need any other sensor information or external reference other than a start and end point. Once the motes are retrieved, the stored data can be converted into the motes relative positions and a map describing the geometry of the environment. This method provides the possibility to map inaccessible or unknown environments where electro-magnetic signals, such as GPS or radio, cannot be used and where placing beacon points is very hard. An example is underground piping systems transporting liquids. Size and energy constraints together with the occurrence of reverberations pose challenges in the way the motes perform their measurements and collect their data. A minimalistic approach in the use of ultrasound is pursued, using an orthogonal frequency division multiplexing technique for the identification of motes. Simulations and scaled air-coupled 45–65 kHz experimental measurements have been performed and show feasibility of the concept.
A basic study on frequency characteristics compensation of sound at ear drum when using hearing aids
Authors: Iseda Hitoshi , Okuma Masaaki
Published: November 2013

Wearing the acoustic equipment such as hearing aids (HAs) and earphones changes the frequency characteristics of sound at the ear drum because the equipment influences acoustic condition of outer ear canal as a partition wall in the canal. This influence should be compensated in order not to degrade the quality of auditory perception. To achieve this, the identification of acoustic property in the canal is required for both cases of with and without HAs. The final goal of this research is to develop a universal method for the frequency characteristics compensation of sound at the ear drum when wearing HAs and incorporating the algorithm of the method into such equipment. In this paper, as the first phase of the research, the authors present the results of an experimental identification technique using simple and large scale models of canal and HAs based on the theory of the transfer matrix method. The result of a compensation experiment using digital filter processing is also presented.
Modeling orchestral crotales as thin plates
Authors: Moore Thomas R. , Zietlow Daniel W. , Griffin Donald C.
Published: November 2013

Orchestral crotales are designed in such a way that the overtones become less harmonic as the fundamental pitch increases. Deutsch, et al. used Kirchhoff-Love theory to show that by eliminating the central mass and choosing the correct ratio of inner to outer radius the overtones can be harmonically related (J. Acoust. Soc. Am. 116, 2427 (2004)). However, when a crotale was constructed using this design, the overtones were not harmonically related. We show that this lack of agreement between theory and experiment is due to the fact that shear motion of the inner boundary, which is neglected in classical thin-plate theory and thought to be unimportant, can significantly affect the resonance frequencies of plates even when they are extremely thin.
Rhythmic techniques and psychoacoustic effects of the percussion music of Steve Reich
Authors: Kvistad Garry M.
Published: November 2013

Beginning in the 1960s, composer Steve Reich began to experiment with rhythmic devises. “Phase shifting” is where unison melodies become canons as one voice speeds up slightly. This was done first with tape loops and later with live performers. In 1967, he applied this technique to “Piano Phase” in which two pianists on two pianos start a pattern in unison. One player slowly speeds up, creating canons which lock in and out of rhythmic “unisons” eventually ending back in melodic unison. This process continues two more times with different patterns. This rhythmic technique was used in several other early works of Reich such as his 1970 composition, “Drumming.” NEXUS member Garry Kvistad has built a multi-element set of percussion instruments tuned in just intonation to perform Piano Phase. The first section is played on a large wooden bar instrument similar to an African Amadinda. The second section is played on a set of thick aluminum tubes. The last section is played on an aerophone activated by slapping the ends of closed tubes. In this presentation, Mr. Kvistad will demonstrate this difficult performance technique using the newly built instruments.
Javanese gong wave signals
Authors: Budhiantho Matias H. , Dewantoro Gunawan
Published: November 2013

In Central Java, the Gong is one of eminent gamelan instrument, an ensemble of predominantly struck instruments that has deep philosophical meaning for Javanese. However, there lack of studies concerning on this particular instrument as a bridging means between scientific description and human artistic perception. This study aims to investigate the spectral and temporal properties as well as particularly look into the typical wave-like sound of the Gong. Acoustic measurements were conducted and analyzed using ARTA. Both frequency and time domain analyses were explored to better understand the nature of the Gong wave signals. The fundamental frequency which decays much more slowly than the other harmonic started with lower increasing frequency. The wave-like sound of the Gong maybe due to signal behavior the resemblance beat phenomenon between early and later development of the fundamental sustaining frequency.
Convergence analysis of filtered-x least mean squares algorithm for active control of repetitive impact noise
Authors: Sun Guohua , Feng Tao , Li Mingfeng , Lim Teik C.
Published: November 2013

The prevalent adaptive active noise control (ANC) algorithm, namely, the filtered-x least mean squares (FXLMS), exhibits a critical challenge for treating transient impact noise. This is because the FXLMS algorithm requires certain adaptation time to converge satisfactorily. However, the FXLMS algorithm may have its learning capacity when the transient noise shows certain repeatability. In this paper, a distinctive theoretical analysis of the convergence behavior of ANC system with the standard FXLMS algorithm is conducted for repetitive impulse-induced transient noise control. To simplify the derivation, the secondary path is assumed to be a pure delay model. Through this analysis, a step size bound condition is derived, and an optimal step size that leads to the fastest convergence is determined. To validate the analysis, extensive numerical simulations are performed considering various pure delay secondary path models. Calculations are in very good agreement with the theoretical analysis. Finally, a more general secondary path is considered to further demonstrate the effectiveness of the FXLMS algorithm for repetitive impulse noise control. The results indicate that ANC system with the FXLMS algorithm can be a very promising technique for repetitive transient noise typically seen in industrial facilities such as punching machines.
Partitioning of seismo-acoustic motions for near-surface explosions and yield estimation
Authors: Rodgers Arthur
Published: November 2013

Explosions near the Earth’s surface excite both atmospheric overpressure and seismic ground motions. The amplitudes of air-blast (and hence acoustic/infrasound) overpressures and seismic motions depend on the explosive yield as well as the height-of-burst (HOB, for above ground emplacement) or depth-of-burial (DOB, for buried emplacement). We present analysis of air-blast overpressures and seismic motions with the goal of developing methods for robust yield estimation for near-surface blasts. Our investigations are based on the HUMBLE REDWOOD set of chemical high-explosive tests at Kirkland Air Force Base in Albuquerque, NM. We find that the air-blast positive phase impulse and seismic P-wave zero-to-peak displacement amplitude are robust estimators of yield. An empirical model for the amplitudes as a function of yield, range and HOB/DOB is presented and allows estimation of yield and HOB/DOB given a set of air-blast and seismic measurements. We find that yield and HOB/DOB can be estimated simultaneously by combining air-blast and seismic measurements. Strong trade-offs between the amplitudes and the yield and HOB/DOB for a single measurement type inhibit accurate estimates. However, simultaneous inversion of both overpressure and seismic measurements improve estimates, justifying combined seismo-acoustic analysis.
Acoustic signals and directivity for explosive sources in complex environments
Authors: Waxler Roger M. , Velea Doru , Bonner Jessie , Talmadge Carrick
Published: November 2013

Much work has gone into characterizing the blast wave, and ultimate acoustic pulse, produced by an explosion in flat, open land. Recently, an experiment was performed to study signals produced by explosions in more complex environments, both above and below ground and in the vicinity of mountainous terrain. Explosive charges, ranging in weight from 200 to 2000 lbs, were detonated in a variety of configurations in and around tubes and culverts as well as buried in alluvium and limestone. A large number of acoustic sensors were deployed to capture the directivity of the signals in the near-field and to characterize the propagation of the signal to the far field. Significant directivity was observed in the near field signals from many of the shots. The influences of both meteorology and topography were evident.
Infrasound from buried seismic sources in the presence of surface topography
Authors: Rodgers Arthur
Published: November 2013

Buried seismic sources (such as explosions and earthquakes) can generate acoustic motions in the atmosphere through coupling along the solid-fluid boundary. Infrasound overpressures from such sources have been computed using the Rayleigh Integral where acceleration time-histories along the boundary are inversely weighted by distance, delayed by travel time and summed at an observation point in the far-field. Typically, these calculations assume the Earth’s surface is flat; however, topography can result in variations of the overpressure signals due to amplitude differences at the surface and phase differences along the direction of propagation. This study considers the Rayleigh Integral to compute far-field overpressure using seismic ground motion simulations that include accurate representation of surface topography. Through a series of numerical experiments we attempt to quantify the effect of surface topography on overpressure signals.
An empirical study of acoustic/infrasonic source and propagation effects using a large dataset of explosions
Authors: Morton Emily A. , Arrowsmith Stephen J.
Published: November 2013

In May 2013 we performed a series of seventy explosion tests, varying the mass, shape, and height of the explosives. Shots were comprised of 11.6 kg, 4.9 kg, and 1.7 kg cylinders and 14.9 kg spheres, all of Comp-B. Explosive heights varied between 4, 2, 1, and 1/2 m above the surface, at the surface, and buried 1 m below the surface. Explosives above the surface were suspended by rope between two concrete pillars. In addition, ground surfaces were altered between dry sand, chicken wire, and concrete blocks. We monitored the explosions on 13 acoustic stations. Four temporary stations were deployed surrounding the shot site at less than 1 km distance. Eight additional stations were at distances of 1 to less than 9 km, and one at ~23 km from the shot site, 4 of which were temporary stations, and 5 are part of the Los Alamos Seismo-acoustic Network. We report on a detailed analysis of signal differences related to explosive and meteorological variations. The large quantity of data from repeating shots enables us to formally characterize the relative importance of source and path variations.
Comparison of primary and secondary calibrations of infrasound microphones from 0.01 to 20 Hz
Authors: Gabrielson Thomas B.
Published: November 2013

Secondary calibration of microphones at infrasonic frequencies by comparison to a reference pressure transducer in a piston-driven chamber is straightforward as long as the two transducers can be located much closer than a wavelength or a correction for their separation can be determined accurately. If the response of the reference transducer is flat to zero frequency, the reference can be calibrated statically. For comparison calibration, the uncertainty is dominated by the uncertainty in the reference. In this investigation, a calibration chamber that is normally used for comparison calibration has been analyzed for primary calibration. In the primary mode, the calibration depends on chamber dimensions, piston displacement, temperature, barometric pressure, leak rate, and a thermo-viscous acoustic model. The primary and secondary calibrations are performed simultaneously; however, the two calibration modes produce almost entirely independent response estimates of both magnitude and phase. The calibrations extend well below the nominal low-frequency roll-off of the microphone and allow identification of the characteristics of the pressure-equalization leak. In addition to the linear analysis, the effects of nonlinearity and convection are explored.
Lateralization of simulated sources and echoes on the basis of interaural differences of level
Authors: Dye Raymond H. , Hill Jacquelyn P. , Ryan Leslie M. , Cupler Alexander E. , Bannon Kevin M.
Published: November 2013

This experiment assessed the relative weights given to source and echo pulses lateralized on the basis of interaural differences of level (IDLs). Separate conditions were run in which the to-be-judged target was the first (source) or second (echo) pulse. Each trial consisted of two intervals; the first presented a 3000-Hz diotic pulse that marked the intracranial midline and the pitch of the target frequency. The second presented the sequence of a source followed by an echo. Target frequency was always 3000 Hz, while the non-target pulse was presented at 1500, 3000, or 5000 Hz. Delays between the source and echo were varied from 8 to 128 ms. IDL’s were chosen for both pulses from Gaussian distributions with μ = 0 dB and σ = 4 dB. Dependent variables included normalized target weight, proportion correct, and the proportion of responses predicted from the weights. Although target weight and proportion correct generally increased with increasing non-target frequency and echo delay for both target conditions, the effects were always larger when the echo served as the target. The superiority of performance when judging echoes vs sources will be discussed in terms of recency effects in binaural hearing.
Revisiting the loudness of sounds with asymmetric attack and decay
Authors: Moore Brian C.
Published: November 2013

Stecker and Hafter [J. Acoust. Soc. Am. 107, 3358–3368 (2000)] compared the loudness of sounds whose envelopes had a fast attack and a slow decay (designated F-S) and a slow attack and a fast decay (designated S-F). They found that, for sinusoidal and broadband noise carriers, S-F stimuli were louder than F-S stimuli of equal energy. They argued that this effect could not be explained by current models of loudness and that the loudness effect may be related to the parsing of auditory input into direct and reverberant sound. Subsequent work has shown that the differences in loudness between F-S and S-F stimuli can be partially accounted for by the loudness model of Glasberg and Moore [J. Audio Eng. Soc. 50, 331–342 (2002)], which incorporates a form of temporal averaging that is asymmetric in time. However, the model does not account for the context effect found by Stecker and Hafter. The largest differences in loudness between F- S and S-F stimuli occurred after pre-exposure to a F-S stimulus. This may happen because, when successive sounds have similarly slow decays, the decaying part is attributed to room reverberation and contributes less to loudness.
Inelastic deformation and failure of partially strengthened profiled blast walls
Authors: Soleiman-Fallah Arash , Nwankwo Ebuka , Langdon Genevieve S. , Louca Luke A.
Published: November 2013

Blast walls that separate the potentially hazardous regions of the topside on an offshore platform were designed to resist lower loads than those envisaged today thus it is desirable to upgrade their blast resistance in a cost-effective and non-intrusive manner. One proposal is to retrofit the existing blast walls partially with centrally located composite patches. This study presents an assessment tool, which provides understanding of the effect of a composite patch on the blast resistance of blast walls. Numerical simulations of a proposed retrofitted wall are performed to gain insight into the failure progression of the wall ab initio. Damage in the composite patch was considered, and the numerical simulations showed that fiber fracture did not occur thus there was no significant loss of in-plane stiffness and strength. Based on these observations, the rapid assessment tool, analytically formulated to incorporate the effect of the composite patch which strengthens the wall and moves the plastic hinge locations away from the wall centre to the composite-steel edge, is deemed a suitable tool. The assessment tool and the numerical simulations are partially validated by the experimental results. The tool runs quickly and provides reasonable accurate predictions for the deformation response of the walls.
Semi-analytical study of interfacial stresses in adhesively bonded single lap joints subject to transverse shock loading
Authors: Nwankwo Ebuka , Soleiman-Fallah Arash , Louca Luke A.
Published: November 2013

Debonding in adhesively bonded lap joints is a detrimental failure mode contingent upon the level of stresses developed in the adhesive. A semi-analytical model is developed to estimate the peel and shear stresses in an isotropic elastic adhesive in a single lap joint subjected to transverse shock loads. The proposed semi-analytical model is an extension of existing mathematical models to study the coupled transverse and longitudinal vibrations of a bonded lap joint system. The adhesive is modeled as an isotropic material in Abaqus. The interfacial stresses obtained by finite element simulations were used to validate the analytical model. The maximum peel and shear stresses predicted by the analytical model in the adhesive were found to correlate well with the maximum stresses predicted by the corresponding numerical models. The peel stresses in the adhesive were found to be higher than shear stresses, a result which is consistent with intuition for transversally pulse loaded joints. The semi-analytical model is able to predict the maxim stresses in the edges where debonding initiates due to the highly asymmetrical stress distribution as observed in the finite element simulations and experiment. The stress distribution under uniformly distributed transverse pulse loading was observed to be similarly asymmetric.
Structural infrasound from a barge collision with the Mississippi River Bridge
Authors: Miller Anna M. , Costley Richard D. , Diaz-Alvarez Henry , McKenna Mihan H. , Simpson Christopher P.
Published: November 2013

The Mississippi River Bridge in Vicksburg MS is a 7 span cantilever bridge 3389 feet long by 68.5 ft wide and is part of the Interstate-20 corridor. On 23 March 2011 around 1:30 pm, a barge moving downstream struck a pier of the bridge. Infrasound stations located at the Waterways Experiment Station (WES) detected the impact. There are indications from the infrasound signatures that infrasound was radiated from the bridge and also from disturbances on the surface of the water (waves or eddies) that resulted from the collision. Finite Element (FE) models of the bridge and pier were developed to simulate the response of the bridge due to the barge impact. It was possible to identify those portions of the infrasound signature produced by vibration of the bridge deck. A synopsis of the accident will be presented along with the recorded infrasound signatures. Results from the dynamic structural model of the bridge will be discussed and related to the infrasound signature.
Tonal alignment in Deori
Authors: Mahanta Shakuntala , Dutta Indranil , Acharyya Prarthana
Published: November 2013

This paper reports on the results from an experiment on tone in Deori, a language spoken by about 20,000 people in Assam (India). Data from 10 speakers where the target word bearing the tonal contrast appeared in the sentence medial position is presented. Time-normalized pitch of different words shows that words may have a lexically specified high or low tone. A high tone may contrast with a low tone, but its phonetic implementation of rise or fall in a disyllabic word depends on whether the syllable on which the contrast appears is initial or final. A tonal contrast on the first syllable leads to a falling contour, but when the contrastive tone appears on the second syllable of a disyllabic word then the tonal contour is falling. Exceptions to this pattern appear in closed disyllables where a steep rise in either the low or high tone is not observed. A high or a low tone may also contrast with a word which is not specified with any tone, in which case there is no rise or fall. Statistical analyses show that Deuri tones exhibit phonetic properties that are dependent on contextual factors like syllable position and segmental properties.
An acoustic description of Chemehuevi
Authors: Tucker Benjamin V.
Published: November 2013

Chemehuevi, a member of the Uto-Aztecan language family, is spoken along the Colorado River in both Arizona and California. The language is extremely endangered with fewer than five known speakers, all over the age of 50. Chemehuevi is classified following Miller et al. (2005) as a dialect of Colorado River Numic along with Southern Paiute and Ute. The present work offers a general description of the acoustic characteristics of the Chemehuevi phoneme inventory based on both an analysis of archival (3 female speakers recorded by: Major, 1969; Tyler, 1972; Press, 1973–1974) and current field recordings (1 male speaker recorded by: Penfield, Serratos, and Tucker, 2005–2006, 2010) of the language. To date, there is little acoustic analysis of Numic languages available. Vowel characteristics are analyzed by extracting duration and the first three formant frequencies. Consonants are also investigated using relevant acoustic measures (such as voice-onset time and centroid frequency). Additionally, the present acoustic analysis is compared to early descriptions of the phoneme inventory and provides evidence regarding the nature of the vowel inventory (is /e/ a phoneme), location of stress, idiolectal differences, and word final voiceless vowels.
The effect of high and low variability conditions on phonetic convergence
Authors: McGuire Grant , Babel Molly E. , Russell Jamie
Published: November 2013

Studies of phonetic convergence using single-word auditory naming tasks offer insight into how variability in stimuli affect the translation from speech perception to speech production. In this paper, we report on an experiment which compares phonetic convergence in single-word production between high variability (mixed talker condition) or low variability (blocked talker condition) using five female model talkers’ voices for the task. Twenty female participants participated in a production task where they produced baseline tokens and shadowed model talker productions in either the high or low variability condition. Phonetic imitation was quantified using listener judgments in an AXB similarity rating task where a model token was compared to a shadower’s baseline and shadowed token. The results indicate a trend towards more convergence in the low variability condition, but this was highly affected by model voice; one model voice was spontaneously imitated more in the high variability condition than the low variability condition. Several socio-cognitive tests were administered to shadowers, and continued analyses of the data will explore whether these individual socio-cognitive measures predict shadowers’ predispositions toward phonetic convergence.
Revisiting the consonantal voicing effect: Flapping in American English
Authors: Beller-Marino Ylana , Bradley Dianne
Published: November 2013

It is long-acknowledged that the consonantal voicing effect—whereby vowel duration is greater preceding voiced vs voiceless consonants (e.g., rib/rip)—is larger in English as compared with other languages, and that the effect’s magnitude generally decreases in multisyllabic forms (e.g., rabbit/rapid). The current study examines consonantal voicing effects in the multisyllabic environment, crucially contrasting non-coronal with coronal cases (e.g., rider/writer). In American English, the latter are subject to a flapping process that surface-neutralizes the voicing distinction. Hence, while both phonological and phonetic sources for a vowel-duration difference are available in non-coronals, flapping eliminates the phonetic source in coronals. We present an analysis of critical vowel durations in elicited productions (target words uttered in a carrier phrase), and confirm the pattern expected if the post-vocalic consonant’s place of articulation matters: the consonantal voicing effect was entirely reliable for non-coronals, but not for coronals. More detailed analyses set aside tokens where flapping failed to apply, and found that the consonantal voicing effect might be altogether absent with coronal place. We speculate that, here, the voicing distinction may have been neutralized in phonological representation, whether that distinction is a matter of orthography (doodle/duty) or is also supported by morphological alternation (rider/writer).
Phonetics as a complement to phonology in the Canadian Shift
Authors: Gardner Matt H. , Roeder Rebecca
Published: November 2013

Previous accounts of the Canadian Shift have interpreted this diachronic change in vowel pronunciation as a purely phonetic consequence of the low back LOT-THOUGHT vowel merger; however, such an analysis does not transparently explain the strong connection between the (phonological) low back merger and the subsequent (phonetic) retraction of the TRAP vowel in the acoustic vowel space. This paper addresses this issue by presenting an analysis of the shift that combines the approaches of Modified Contrastive Specification theory and the Contrastive Hierarchy—two phonological frameworks—with phonetic insights from Vowel Dispersion-Focalization theory. We propose that the catalyst of the Canadian Shift is a three-way vowel merger, in combination with a simultaneous change in the underlying feature specifications of the TRAP vowel. This results in a phonology that allows for the TRAP and DRESS vowels to succumb to the influence of the phonetic principles of dispersion and focalization. This hypothesis is illustrated by comparison of data from 59 speakers in Thunder Bay, Ontario, and Industrial Cape Breton, Nova Scotia. Our analysis predicts that a Canadian Shift-type phonetic change will occur in any North American dialect of English where the PALM-LOT-THOUGHT merger occurs, unless an intervening phonological change alters systemic contrasts.
Acoustic correlates of consonant gesture timing in English
Authors: Selkirk Elliot , Durvasula Karthik
Published: November 2013

There is extensive research on the organization of syllable-structure as indexed by the relative timing of the articulators (Browman and Goldstein, 1988; Byrd, 1995; Shaw et al., 2011 inter alia). The research suggests consonants in complex onsets (in words such as scream, stream…) are aligned to a single position called the C-center, the mean of the midpoints of the onset consonants. However, such research typically uses very expensive articulatory equipment (X-ray Microbeam, Electromagnetic Articulography…). This restricts the research to a few laboratories across the world with access to such technology. Here, we explore the possibility of using acoustic measurements, which are cheaper and more accessible, for such research. We conducted an experiment on 6 native speakers of English, who produced 12 repetitions of 24 English words (12 test, 12 filler) that varied in the number of onset consonants (C1, C1C2, C1C2C3) in three different vowel contexts. Paralleling previous studies, the results show that onset consonants align with the C-center even in acoustic measurements. The results suggest acoustic data has at least some meaningful information about gestural organization. Therefore, they prompt the (nuanced) use of acoustic techniques to study such effects.
Coarticulation and contrast in static and dynamic models of second formant trajectories
Authors: Dutta Indranil , Redmon Charlie
Published: November 2013

Real (Stevens et al., 1966) and virtual F2 locus (Sussman et al., 1991) measures are presented for Malayalam lingual plosives. We show that in distinguishing voiceless coronals (dental, alveolar, and retroflex) in VCːV sequences, F2 onsets derived from first-order locus equations (LEs) show only partial delineation of the contrast. The dental-alveolar contrast is effectively maintained, but retroflex and alveolar stops show no significant difference in F2 onset. Following Lindblom and Sussman’s (2012) examination of LEs as a measure of relative coarticulatory resistance, we report F2 slopes for the three coronal stops in VC and CV transitions to assess the implications of this metric in Malayalam. Our findings on the ordering of slope values from steepest to flattest did not follow predictions based on expectations of relative articulatory complexity; namely, alveolars generated a flatter slope than retroflexes, despite Dart and Nihalani’s (1999) demonstration that the retroflex gesture is more complex within the coronals. These results, when compared with temporal measures from exponential models of formant trajectories at consonant implosion and release (i.e., transition velocity and projected F2 locus), suggest a necessary distinction between coarticulation-based place of articulation categorization and formant transition cues utilized in maintaining stop place contrasts.
Estimation of vocal tract input impedance at the glottis from formant measurements
Authors: Lulich Steven M.
Published: November 2013

It is well known that the mapping from articulation to acoustics is many-to-one or many-to-many, so that so-called “articulatory-acoustic inversion” is a challenging problem. What has not been noted, however, is that the input impedance from the glottis can be determined from the inverted articulatory configuration regardless of whether this configuration is accurate. This can be useful as a step toward estimating the acoustic load on vocal fold vibration during phonation. The theory and procedure for thus obtaining estimates of the vocal tract input impedance is presented, its relation to the Mermelstein/Schroeder method is shown, and its limitations are discussed. Finally, experiments with synthetic and naturally produced vowels are presented and discussed. It is shown that the estimated input impedance is accurate up to the highest measured formant, with the largest deviations centering around the formant frequencies due to errors in formant measurements and the handling of acoustic losses.
Modeling the listener? What resets acoustic durations of repeated English words
Authors: Vajrabhaya Prakaiwan , Kapatsinski Vsevolod
Published: November 2013

Listener-based accounts of speech production claim that speakers modify their speech based on their evaluation of the listener’s state of knowledge (Lindblom, 1990). In line with this, repeated words shorten when they have been previously said to the same listener (Fowler, 1988); however, repetition across an episode boundary in a narrative does not lead to decreased acoustic duration (Fowler et al., 1997). We replicate Fowler et al.’s story boundary effect and extend the study by testing whether a switch in listener has an additional effect on word duration. Speakers were asked to tell and retell the same story in the sequence of (A) listener 1/(B) listener2/(C) listener1 again (Galati and Brennan, 2010). We expect word durations to reset when the speaker starts a new narrative, especially when there is a switch in listener. In other words, word durations should be comparable in conditions (A) and (B), but shorter in (C), since the listener in condition (C) has heard the story before. Acoustic data from 20 American English native speakers have been collected and transcribed; data analysis is ongoing. This study is intended to shed light on the interplay between production economy and the need to transmit information.
Acoustic analysis of initial consonants in the California Syllable Test
Authors: Yund E. W. , Ettlinger Marc , Woods David L.
Published: November 2013

The goal of the present study is to conduct an acoustic analysis of onset consonants to identify the spectrotemporal features that distinguish them from each other and to identify acoustic consonant variations that produce the observed patterns of perceptual confusions seen in young- and older-normal-hearing listeners [J. Acoust. Soc. Am. 127, 1609–1623 (2010); JRRD 49, 1277–1292 (2012)]. We used the California Syllable Test (CaST) token set, which includes 40 exemplars of each initial consonant for each of three vowels and six talkers. The CaST measures recognition of 20 initial and 20 final consonants in speech-spectrum noise with each consonant presented at a 67%-correct signal-to-noise ratio (SNR). Time-normalized spectrograms are computed for each exemplar (from consonant onset to the end of the formant transition) by varying the time-spacing of the FFT spectral lines in proportion to the exemplar duration. Quantitative comparisons among normalized spectrograms of correctly recognized and confused exemplars at a range of SNRs suggest explanations for specific consonant confusions. The long-term goal is to apply this analysis to understand the effects of hearing loss and HAs on consonant perception and to predict consonant confusion patterns obtained with the CaST in normal-hearing and hearing-impaired listeners.
Acoustic characteristics of a dielectric elastomer absorber
Authors: Lu Zhenbo , Cui Yongdong , Zhu Jian , Zhao Zijie , Debiasi Marco
Published: November 2013

The present paper is devoted to study the acoustic characteristics of a dielectric elastomer (DE) absorber, which has a wide variety of potential applications as a novel actuator technology. DE, a lightweight and high elastic energy density smart material, can produce a large deformation under high DC/AC voltages. These excellent characteristics can be used to improve the present typical noise control systems. The performance of using this new soft-controlled-material is experimentally investigated. It is found that the voltage on the DE could tune the resonance frequencies of DE absorber thus it could absorb broadband noise. The results also provide insight into the appropriateness of the absorber for possible use as an active noise control system for replacing the traditional acoustic treatment.
Disyllabic Mandarin lexical tone perception by native Dutch speakers: A case of adult perceptual asymmetry
Authors: Hoffmann Christian , Sadakata Makiko , Chen Ao , McQueen James M.
Published: November 2013

Asymmetries in the perception of lexical tones have previously been reported in infant studies: the order in which certain tones are presented influences discrimination accuracy. Using disyllabic materials, the current study provides evidence that such asymmetries can be found for L2 learners of Mandarin Chinese as well, making their responses in identification and discrimination tasks qualitatively different from adult native speakers. Using an active oddball paradigm, we found that Tone 4 deviant within a Tone 1 standard environment was consistently easier to discriminate than the reverse condition. Furthermore, this difference is also reflected in amplitude differences of the auditory N2/P3 complex. In two subsequent EEG experiments, we systematically varied (a) the relative acoustic difference between standards and deviants and (b) stimulus variance within standards and deviants. Results indicated that both decreased acoustic difference as well as increased stimulus variance positively increase relative perceptual asymmetry as well as the relative difference between ERP responses. Finally, we compare multiple mechanisms by which the native/non-native pitch system might cause these perceptual asymmetries.