bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound diffusion design process using scale models of a concert hall and acoustic parameters
Authors: Jo Hyun In , Jang Hyung Suk , Jeon Jin Yong
Published: October 2018

This study proposed a design process for diffusion walls of the Art Center Incheon concert hall by using scale models and verified the sound diffusion performance in comparison with acoustic parameters. Locations of diffusers and main diffusing surfaces were determined in a 1:50 scale model, and the heights of diffusers in the stage were set and diffusion rates were evaluated according to occupancy density in a 1:25 scale model. A 1:10 scale model enabled the real acoustic characteristics of the concert hall to be evaluated. This model was used to measure scattering/diffusion coefficients of diffusers in each part and to design the finishing shapes of walls. Horizontal diffusers with the highest protrusion were installed on the lateral walls near the stage in order to orientate scattered reflections. Impulse responses were used to investigate acoustic parameters like RT, EDT, G, and C80, and the number of peak reflection (Np) was calculated to compare diffusion performance. It turned out that, when the amount of diffusion changed, the value of Np increased but the values of RT, EDT, and G and the corresponding relative standard deviation (RSD) decreased. The ratio of 1:25 or higher scale models were efficient in designing the diffusion surfaces of the concert hall. The effectiveness of scale models was verified as the directions, locations, protrusion heights, and areas of diffusers were determined.
Searching for the FishOASIS: Using passive acoustics and optical imaging to identify a chorusing species of fish
Authors: Pagniello Camille , Butler Jack , D'Spain Gerald L. , Jaffe Jules , Parnell Ed , Širović Ana
Published: October 2018

Marine protected areas have been established off the California coast to ensure the persistence and resiliency of the marine ecosystems found here. Kelp forest habitats, in particular, support a diverse assemblage of fishes, many of which produce sound. From May to September 2017, a low-frequency (325–545 Hz) chorus was recorded near the kelp forests off La Jolla, California. The chorus begins each day approximately a half-hour before sunset and lasts for about 3–4 hours. During these times, spectral levels around 400 Hz increased by approximately 30 dB over, although there is significant day-to-day variability in received level. To identify the chorusing fish species, a Fish Optical and passive Acoustic Sensor Identification System (FishOASIS) was developed, consisting of a four-channel SoundTrap ST4300 acoustic recorder and four Sony α7s II cameras. Frequency-domain beamforming was used on signals recorded by the four-element, 20-m aperture, tetrahedral-shaped array to estimate the location of the fish chorus, which appears to be fairly fixed over time. The chorus also was used as a source of opportunity to measure transmission loss in order to determine whether kelp forests can act as acoustic refuges by sufficiently attenuating chorusing sounds. [Research supported by California Sea Grant and NSERC Postgraduate Scholarship-Doctoral.]
Arctic ambient noise statistics at the edge of the Canada Basin
Authors: Whitt Christopher , Martin Bruce , Pecknold Sean , Badiey Mohsen , Cole Aidan
Published: October 2018

Knowledge of ambient noise is important for the design and operation of acoustic observation and communication systems. Several concurrent year-long acoustic datasets from the Canada Basin Acoustic Propagation Experiment (CANAPE) were collected in 2016–2017. Selected data were analyzed to investigate soundscape temporal and spatial characteristics in an area on the western slope of the Chukchi shelf and Canada Basin, north of Barrow Alaska. From October 2016 to October 2017, four 8-element vertical arrays were deployed in water depths between 100 and 300 m. Each array recorded at approximately 15% duty cycle at several sample rates between 4000 Hz and 64000 Hz and at 24-bit resolution. One-minute, 10-second, and 1-second root-mean-square sound pressure levels were computed to generate ambient noise statistics and summarized in empirical probability density functions (PDF) for various bands. Fit functions for ambient noise were determined for each empirical PDF. Impulse detection was used to investigate potential correlation of ice cracking with ambient noise. A multivariate correlation of ambient noise levels was performed with several environmental parameter covariates, including ice cover, wind speed, and air temperature. These correlations may form the basis for predictive models for ambient noise modeling in the arctic.
A short history of ONR ice camps: 1978–1994
Authors: Baggeroer Arthur B.
Published: October 2018

The Office of Naval Research sponsored Arctic field programs almost every year from 1978 to 1994 during the height of the Cold War. Almost all of them had an acoustics component coupled with observations for physical oceanography, geoacoustics, plate tectonics, ice mechanics, and used both active and passive methods. In 1978, these started with emphasis on basin reverberation and ended in 1994 with trans Arctic Ocean tomography. They had acronyms from CANBARX (Canadian Basin), FRAM I—IV, MIZEZ (Marginal Ice Zone), PRUDEX (Prudoe Bay) CEAREX and SIMI/TAP (Sea Ice Mechanics/Trans Arctic Propagation). The author was the chief scientist for most of these programs and will provide an overview of ONR's efforts in the Arctic during the Cold War. [Work supported by ONR.]
Spectral, spatial, and temporal characteristics of underwater ambient noise in the Beaufort Sea in 1994 and 2016
Authors: Chen Rui , Poulsen Andrew J. , Schmidt Henrik
Published: October 2018

Climate induced changes in the Arctic Ocean have severely impacted underwater acoustic communication and navigation; understanding underwater noise characteristics is critical to improving the performance of these operations. Ambient noise from the Beaufort Sea recorded in experiments more than 20 years apart (SIMI94 and ICEX16) are compared to determine differences that may be attributed to the region's rapidly changing environment. Both datasets are collected at spring time under packed ice conditions with 32 element vertical line arrays. Spectral comparison shows noise within 20–300 Hz band is 30–40 dB louder in 1994 than 2016, suggesting the ice cover during SIMI94 was more acoustically active. Beamforming results show ambient noise vertical directionality is focused near the horizontal during SIMI94 but more spread in elevation during ICEX16, with a robust noise notch at the horizontal. Numerical modeling demonstrates that this difference may be attributed to ambient noise during ICEX16 being dominated by surface noise sources at discrete ranges rather than the historical assumption of a continuous and uniform distribution of sources. Temporal statistics of transient ice events show more transient activity during SIMI94 and appear to support the new proposed surface source distribution for ICEX16. [Work supported by ONR and DARPA STO.]
Acoustic response of a migrating bowhead whale population to open-ocean ambient noise levels
Authors: Thode Aaron , Blackwell Susanna B. , Kim Katherine H. , Conrad Alexander
Published: October 2018

Automated and manual acoustic localizations of migrating bowhead whale calls in the Beaufort Sea were used to examine their acoustic response to changes in wind-driven, continuous, ambient noise levels. At low noise levels, the population’s source levels and calling rates increased with increasing noise level, with the source level distribution adjusting to maintain a consistent functional detection range, estimated to be between 20 and 60 km. However, once noise levels exceeded the 75thpercentile of their long-term distribution, source level increases failed to keep pace with further increases in noise level, thereby reducing the population’s detection range and associated communication space. Call production rates, on the other hand, continued to increase even up to the highest noise levels. Migrating bowhead whales thus attempted to maintain long-range call detectability by adjusting their source level and calling rate. Beyond a certain noise level, whales cannot increase their source levels, but do continue to increase their calling rate. The results provide context for interpreting the effects of industrial noise on bowhead whale acoustic behavior; for example, distant airgun signals stimulate an increase in mean call production rate equivalent to a 26 dB increase in natural ambient noise levels. [Work sponsored by NPRB.]
Monitoring the Arctic acoustic environments with the International Quiet Ocean Experiment
Authors: Blondel Philippe , Sagen Hanne
Published: October 2018

The northern high-latitude regions, including the Arctic Ocean, are becoming increasingly important as a result of global warming and their growing economic and political interests. Sea ice reduction is facilitating resource exploration, marine transport, and other economic activities in the regions. Warming waters lead to shifts in marine ecosystems and in soundscapes. Exploitation of resources in the Arctic is expected to grow in the coming decades, offering new opportunities for marine and maritime industries. To measure the environmental impact of ocean noise at a variety of spatial and temporal scales, the International Quiet Ocean Experiment (http://iqoe.org/) established in late 2017 a working group on Arctic Acoustic Environments. The first activities of the Working Group are focusing on identifying locations and times of existing and past acoustic studies in the Arctic Ocean, and synthesise the state-of-the-art on sounds, past, present, and future in the Arctic Ocean. WG activities at the Arctic Observing Summit 2018 (Davos, Switzerland) are linking with indigenous communities and other local stakeholders, to address emerging trends in marine transport and Arctic resource exploitation, and to plan for where/when the optimal acoustic surveys could be, and what metrics they should prioritise.
Therapeutic ultrasound transducers conformal to medical needs
Authors: Lafon Cyril , N'Djin Apoutou , Melodelima David , Chavrier Françoise , Loyet Raphaël , Chapelon Jean-Yves
Published: October 2018

The use of ultrasound for therapy has seen a growing interest since the nineties and the development of endorectal transducers for ablating thermally prostatic tissues. Different devices are currently under clinical evaluation for the treatment of many disorders. Numerical modelling plays a significant role in these developments. For each clinical need, it allows defining the geometry of the transducer and the exposure conditions. The technology for manufacturing the transducer is chosen according to the required acoustic output, density of elements, frequency bandwidth, and medical use (endocavitary, disposable, implantable…). The imaging modality for treatment monitoring is also critical and should be considered in the design process. The goal of this presentation will be to list the various challenges faced during the design of a therapeutic transducer, discuss some solutions that were proposed, and illustrate the process with different examples.
Dual-mode capacitive micromachined ultrasonic transducer arrays for high intensity focused ultrasound and imaging
Authors: Jang Ji Hoon , Chang Chienliu , Rasumssen Morten F. , Brenner Kevin , Stedman Quintin , Ergun Arif S. , Khuri-Yakub Butrus T.
Published: October 2018

High Intensity Focused Ultrasound (HIFU) therapy requires imaging guidance to ensure that the correct area is treated. Guidance may be provided by magnetic resonance imaging or ultrasound imaging. With piezoelectric transducers, ultrasound imaging guidance is typically done with a separate transducer array since it is difficult to obtain sufficient imaging and HIFU performance with the same transducers. However, Capacitive Micromachined Ultrasonic Transducers (CMUTs) can have sufficient bandwidth and efficiency to allow both HIFU therapy and imaging to be done with the same transducer array. Additionally, CMUTs have much lower self-heating than piezoelectric transducers and require less cooling when used for HIFU. This means that CMUT-based HIFU systems can be made smaller than other HIFU systems to date, allowing access to treatment areas that were not previously possible. In addition, using the same array for imaging and treatment eliminates challenges with co-registration. We have constructed a dual-mode HIFU and imaging probe using a 32x32 CMUT array integrated with an application-specific integrated circuit. Ultrasound imaging guided ablation of ex-vivo tissue has been demonstrated with the probe, with rapid switching between HIFU and imaging mode.
Enhanced shock scattering histotripsy with pseudo-monopolar ultrasound pulses
Authors: Li Yige , Hall Timothy L. , Xu Zhen , Cain Charles A.
Published: October 2018

Shock scattering histotripsy (SSH) involves a complex interaction between positive and negative phases of an acoustic burst to initiate a robust cavitation bubble cloud. To more precisely study these effects and optimize SSH therapy, we constructed a frequency compounding transducer to generate pseudo-monopolar ultrasound pulses. The transducer consisted of 113 individual piezoelectric elements with various resonant frequencies (250 kHz, 500 kHz, 750 kHz, 1 MHz, 1.5 MHz, 2 MHz, and 3 MHz). For each resonant frequency, a nearly 1.5-cycle pulse could be generated. Pseudo-monopolar peak positive pulses were generated by aligning the principal peak positive pressures of individual frequency components temporally so that they added constructively, and destructive interference occurred outside the peak-positive-overlapped temporal window. After inverting the polarity of the excitation signals, pseudo-monopolar peak negative pulses were generated similarly by aligning principal peak negative pressures. Decoupling the positive and negative acoustic phases could have significant advantages for therapeutic applications enhancing precision, avoiding cavitation at tissue interfaces, and reducing the acoustic aperture required for effective therapy. For example, we show that 16 SSH bubble clouds can be generated using only peak positive pulses following a single peak negative pulse. This results in a precise elongated lesion within red-blood-cell phantoms.
New international standards for high pressure therapeutic ultrasound fields
Authors: Szabo Thomas L.
Published: October 2018

High pressure levels of strongly focused therapeutic transducers create new challenges for formulating international standards for measurement and simulation. Earlier efforts of Working Group 6, High Intensity Therapeutic Ultrasound and Focusing Transducers, Technical Committee 87 of the International Electrotechnical Commission, resulted in a standard for measuring high power (up to 500 W) and a specification for measuring ultrasound fields at lower amplitudes using existing linear methods and scaling up to higher therapeutic levels. Presently, work is underway on a new document to describe direct approaches for characterizing ultrasound pressure fields in water up to 100 MPa through the use of state of the art optical and robust hydrophones. Because the real goal of our efforts is to determine therapeutic pressure levels in tissue at a target site, we have initiated work on a second hybrid approach which combines characterization of the radiated field close to the transducer in water with nonlinear field simulation programs. In this way the characterization data which preserve the uniqueness of a particular transducer are used as input to a simulator program for realistic field prediction. Our group is addressing how to simulate nonlinear propagation in heterogeneous absorbing tissues accurately and to benchmark simulation software.
Acoustic beam pattern for a push-pull laser interferometric sound sensor
Authors: McBeth Michael S.
Published: October 2018

A push-pull laser interferometric sound sensor uses two parallel laser beams where both beams are exposed to the sound filled fluid. In arrays of conventional piezoelectric hydrophones, each array element produces a voltage and the beam pattern is obtained by deriving the response as a function of acoustic wave angle in terms of electrical power divided by the maximum response power along the acoustic axis. In a push-pull laser interferometric sound sensor the response function is an optical path difference or phase difference between the two laser beams as a function of acoustic wave angle. In an analogous way, we derive a response function in terms of the optical path difference between two optical line sensors as a function of acoustic wave angle and divide by the response along the acoustic axis. This normalized response function is squared to obtain the beam pattern for a push-pull laser interferometric sensor. We compare this beam pattern to that of a conventional line array.
MEMS microphone based on the membrane with bias voltage and FET (field effect transistor) mechano-electrical transduction
Authors: Kim Junsoo , Lee Hoontaek , Kim Chayeong , Seo Donghwan , Shin Kumjae , Moon Wonkyu
Published: October 2018

Most commercially available microphones use a capacitive method, and their structure and performance are saturated to some extent. However, due to the limitation of the capacitive transduction method, the roll-off at the low frequency is inevitable, and there is a limit in reducing the mechanical thermal noise caused by the squeeze film damping that occurs between the membrane and backplate structure. Proposed FET (field effect transistor) based MEMS microphone detects a change in the source-drain current according to the gate voltage change of the FET induced by vibrating the membrane with the electric field. In the case of a MEMS microphone using the proposed FET, low frequency roll-off according to the energy conversion does not occur, and the size of the backplate can be drastically reduced as compared with the conventional MEMS microphone, thereby further reducing the mechanical thermal noise, leading to the possibility of achieving the higher SNR (signal to noise ratio). In this study, design and fabrication, performance test of the proposed FET based MEMS microphone are conducted. [Work supported by CMTC, UM15304RD3.]
Production method for simulcast in 22.2 multichannel sound broadcasting
Authors: Sugimoto Takehiro , Komori Tomoyasu
Published: October 2018

The 8K with 22.2 multichannel (22.2 ch) sound broadcasting is planned to be launched since December 2018 in Japan. NHK is going to simulcast 2-channel stereo and 5.1 surround together with the 22.2 ch sound for backward compatibility with existing home reproduction equipment, e.g., AV receiver and soundbar. However, individual production for each audio format is impractical because it needs many engineers and a lot of production equipment compared with a production in single format. Hence, an efficient production method for simulcast which does not demand additional production resources is required. The first proposal is a tone compensation for downmixing from the 22.2 ch sound to the other audio formats. The energy spectrum of the downmixed signal is compensated to harmonize with that of the 22.2 ch sound. The second proposal is a loudness chase to have the loudness level of the downmixed signal follow that of the 22.2 ch sound. The loudness level of the downmixed signal usually differs from that of the 22.2 ch sound, so that the loudness chase successively adjusts the loudness level without unnatural level change and matches them by the end of the program.
Distributed acoustic sensing for near-surface seismic applications
Authors: Costley Richard D. , Galan-Comas Gustavo , Hathaway Kent K. , Ketcham Stephen A. , Kirkendall Clay K.
Published: October 2018

Distributed acoustic sensing (DAS) has been used in the oil and gas industries for vertical seismic profiling (VSP) for approximately the past ten years. Its use for near-surface seismic surveys has also been investigated. This study relates to these types of applications. DAS consists of a buried optical fiber cable with one of its fibers connected to electro-optical instrumentation, i.e., an optical interrogator. The interrogator injects pulses of coherent light into the fiber and receives backscattered light. Seismic disturbances deform the cable, strain the interrogated fiber, and change the fiber’s optical path length. The resulting phase changes of the backscattered light are recorded by the interrogator. These phase change measurements, proportional to strain, are probed through time at spatially sequential (i.e., “distributed”) segments along the length of the fiber. The length of each segment is referred to as the gauge length. A single fiber is thus a nominal array of sensors with the gauge length defining the spatial separation. Here, we present DAS signals from ground vibrations caused by impact-hammer and electro-magnetic-shaker sources. The signals were recorded simultaneously by geophones for comparison. Interrogator modifications allowed selectable gauge lengths, 10, 4 and 2 meters. The experimental results demonstrate the benefits of higher resolution.
Experimental investigation of the impacts of total temperature non-uniformities on the flow and acoustic fields of a heated supersonic jet
Authors: Daniel Kyle A. , Mayo David , Lowe Kevin T. , Ng Wing
Published: October 2018

In recent years, the noise produced by tactical aircraft has become a growing concern due to stricter community noise standards and the negative health effects it has on flight support personnel. This study proposes the examination of a new novel noise reduction method involving thermal non-uniformities in heated supersonic jets. Thermal non-uniformities have the advantage of increasing turbulent mixing in jets without the use of additional hardware and can most likely be implemented in afterburning engines with minimal modification. In the course of this study a thermally non-uniform Mach 1.5 heated jet with a centered and offset thermal non-uniformities will be examined. It will be shown that thermal non-uniformities reduce the far-field radiated noise up to ~2dB at peak frequencies and have a measurable impact on the directivity of radiated noise, including a narrowing of the Mach wave emission angle and a non-uniform azimuthal directivity. These changes in the acoustic field are directly related to global changes in the turbulence development observed in the jet. These effects include a shortened potential core, increased shear layer thickness, and a decreased mean flow in regions of peak Reynolds shear stress. These effects are captured by stereoscopic PIV and near and far-field microphone measurements.
Visualization of acoustic phenomena of imperfectly expanded supersonic jets using acoustic-triggered conditional sampling analysis
Authors: Sekiguchi Yuya , Okamoto Koji , Teramoto Susumu
Published: October 2018

For rockets and supersonic aircrafts, acoustic waves from an exhaust jet cause problems of vibration and noise. To reduce the influence of acoustic waves effectively, it is important to reveal characteristics of acoustic phenomena, such as source locations and the relation between the flow and acoustic phenomena. For this purpose, the authors carried out visualization of acoustic field of a correctly expanded supersonic jet in the previous studies, and proposed the acoustic-triggered conditional sampling analysis to obtain acoustic information from high speed schlieren movies. This method is also expected to be applied to other jet acoustic phenomena. In this study, this method is applied to imperfectly expanded supersonic jets and the relation between the flow and acoustic phenomena will be discussed.
Design and evaluation of a high-speed aeroacoustic wind tunnel
Authors: Rocha Joana
Published: October 2018

The high-speed aeroacoustic wind tunnel (HSAWT) at Carleton University is a new facility commissioned with the purpose of facilitating experimental studies of turbulent boundary layer (TBL) induced surface pressure fluctuations. This research is primarily intended for applications related to aircraft cabin noise generation from structures exposed to high-speed flow. This open-jet, blowdown wind tunnel is a unique facility in Canada and one of a few aeroacoustic wind tunnels in the world capable of achieving speeds up to Mach 0.8. Flow is delivered from a nozzle with dimensions of 6.1 cm × 15 cm to a test section enclosed within an anechoic chamber with internal dimensions of 1.9 m × 0.88 m × 1.95 m. This study details the complete design methodology for all major wind tunnel components, including the numerical simulations performed in the validation of the designed components. Results of preliminary test section flow characterization and chamber background noise measurements are discussed. Finally, experimental results of the TBL surface pressure fluctuation spectral behavior developed over a flat test section plate are compared with established data and empirical models available in literature.
Experimental study on aerodynamic noise characteristics of high-lift configuration with variable gap leading-edge slat
Authors: Lu Weishuang , Liu Peiqing , Guo Hao
Published: October 2018

The aircraft high-lift devices are important components to ensure the safety of take-off and landing, and it is also the main source of airframe noise in the process of take-off and landing, especially the leading-edge slat. The slat that reduces gap by rotating with the fixed axis is proposed in this paper, and experimental study of far-field aerodynamic noise characteristics of high-lift configuration with the slat is also carried out. The experimental results show that discrete tones in the low-middle frequency range disappear and the broadband frequency amplitude also slightly decline, resulting in a significant decrease in the overall sound pressure level of the high-lift configuration with slat gap of 0, compared with the configuration with conventional leading-edge slat. However, in the process of rotation from conventional slat to seamless slat, more prominent discrete tone in low-middle frequency range or humps in mid-high frequency range appear at angles of attack below 6°, which give rise to the overall increase in the sound pressure level. At angles of attack above 6°, these aero-acoustic phenomena are not obvious. Hence, the overall sound pressure levels of high-lift configuration gradually decrease with the rotation process in larger angles of attack.
Behavioral and neural spatial acuity can be persistently reduced by early temporary hearing loss
Authors: Tollin Daniel J. , Anbuhl Kelsey
Published: October 2018

Children experiencing asymmetrical hearing early in life, typically due to conductive hearing loss (CHL) associated with ear infection, often display reduced behavioral spatial acuity that persists long after hearing is restored, suggesting abnormal central auditory development. We hypothesized that persistent CHL disrupts the experience-dependent fine-tuning of binaural hearing necessary in the developing auditory system to support normal behavioral spatial acuity. Using an animal model (the guinea pig), we found that chronic unilateral CHL during development (induced by an earplug) caused the brain to generate a less precise representation of auditory space. When the hearing loss was reversed by simply removing the earplug, both the spatial acuity of single neurons in the inferior colliculus and behavioral performance in a simple sound location acuity task were ~threefold worse than animals that had not worn earplugs, as if the sense of auditory space had been blurred. Overall, the results suggest that experiencing even temporary hearing loss during early development can persistently alter the normal maturation of the auditory brain circuits that are necessary to support good spatial acuity. Thus, the maladaptive plasticity in these circuits due to temporary hearing loss during development can place limitations on spatial acuity in adulthood. [Support: R01-DC011555, T32-DC012280, F31-DC014219.]
Lateralization of interaural time and level differences measured with cochlear implant sound processors
Authors: Kan Alan , Litovsky Ruth
Published: October 2018

Recently, our lab developed a novel technique that enables binaural sensitivity to be measured via unsynchronized clinical cochlear implant (CI) sound processors. By using a transposed-tone complex with carrier frequencies at the center frequency of the patient MAP, bilateral CI users have measurable sensitivity to interaural time and level differences (ITD and ILD, respectively) that is on par with results from bilaterally synchronized research platforms. In this work, we measure the extent to which a transposed-tone complex presented via clinical processors can be mapped to lateral locations in the head as a function of changes in ITD and ILD. In addition, lateralization was measured when ITDs and ILDs co-varied. Results show that listeners are able to lateralize the tone complex throughout the range of the head. However, the slope of the ITD lateralization function appears to be shallower than that of ILDs. When ITDs and ILDs co-vary, the slope of the lateralization function appears to follow that of ILDs, suggesting that bilateral CI users may not be combining the two cues for sound source lateralization.
Exploiting spatial audio cues for pilot navigation in degraded visual environments
Authors: Jones Heath , Milam Lana , Karch Stephanie , Williams Henry , Simpson Brian
Published: October 2018

Aviation mishaps resulting from degraded visual environments (DVEs) represent a significant loss in military personnel and aircraft every year. DVEs are considered any type of environmental condition (e.g., sand, snow, or fog) that visually obstructs the pilot and can cause spatial disorientation. The current study represents a tri-service effort exploring the implementation of spatial audio cueing techniques to aid pilot navigation in DVEs. Directional cueing (i.e., indicating the location of target waypoints) was achieved by spatializing an auditory stimulus using the SoundLab audio rendering package and convolving audio signals with (non-individualized) head-related transfer functions. Two spatial cue conditions were tested, either rendered dynamically in reference to the pilot’s head via head tracking or with respect to aircraft heading. Data were collected from pilots operating a full-motion UH-60 Black Hawk flight simulator at the U.S. Army Aeromedical Research Laboratory. Pilots performed multiple flight maneuvers, such as a “turn to target” localization task, a "side-step" maneuver positioning the aircraft over a stationary target, and an “approach to moving target” task. Performance was assessed by measures of localization error, completion time, and failure rate. Findings from this study provide information on sensory cueing display countermeasures for helicopter flight in DVEs.
Monocoque shell and tube heat exchanger for thermoacoustics
Authors: Keolian Robert M. , Bastyr Kevin J. , Wakeland Ray S. , Brady John F.
Published: October 2018

Heat exchangers can be a limiting factor to thermoacoustic power density. They can also be difficult to construct because of a tendency toward many small parts due to the small size of the thermal penetration depth. We present a heat exchanger that consists of around five pieces and yet has very small feature size and is easy to construct in large numbers. A sacrificial mandrel, consisting of a sheet with a lattice of specially shaped holes, is formed by casting in a mold with a lattice of specially shaped pins. The mandrel is plated with nickel, electroless nickel, or other metal. The mandrel is then removed by melting or dissolving, leaving a monocoque tube bundle. A screen mesh may be joined to one or both faces of the monocoque to act as fins to improve thermal contact to the working fluid that flows through the tubes. Coolant flows around the tubes within the monocoque shell. For a typical device, we find that without a mesh on the monocoque, lost work is minimized with tubes on the order of 8 mm long and spaced by 0.4 mm, but with a 100-mesh copper screen on both faces, the tubes can be a more manageable 3 mm long spaced by 4 mm.
Study on a coaxial thermoacoustic system: Effect of the edge shape on the acoustic intensity
Authors: Takeyama Yukihiro , Sakamoto Shin-ichi , Saeki Masaya , Kuroki Daichi , Watanabe Yoshiaki
Published: October 2018

For the downsizing, the coaxial thermoacoustic system (coaxial-type) has been proposed. The coaxial-type is expected to have high efficiency because the energy conversion with traveling wave phase like looped-tube is realized. Additionally, this system is more compact than the looped-tube. The circular flow path of the coaxial-type is made of an annular flow path between the inner and the outer tube and a cylindric flow path in the inner tube. By propagating in the cylindric flow path after passing through the annular flow path, a traveling-wave sound field is generated. The edge space between the annular flow path and the inner tube was studied due to the reduction of the propagation loss. The influence of the inner tube length and the edge shapes of outer tube on the energy conversion was examined. The two edge shapes were used: the flat one and the spherical one. It was confirmed the sound energy generated in the system with the spherical shape is higher than the one with the flat shape. It is suggested a traveling-wave sound field is easily generated by the spherical shape because of the focus effect. Thus, the edge shape is one of important points for designing the coaxial-type.
High power-density thermoacoustic sound projectors
Authors: Aliev Ali E.
Published: October 2018

Design, fabrication, and performance of large size and high power-density encapsulated thermoacoustic sound projectors driven by short pulses will be presented. The analysis of enhanced energy conversion efficiency using proper signal processing and low-dimensional thermodynamics will be given. [Work supported by the Office of Naval Research and Army Research Office.]
Investigations in performance of a gas-combustion infrasound source
Authors: Smith Chad M. , Gabrielson Thomas B.
Published: October 2018

Designing a coherent (non-explosive) sound source within the infrasound band (0.1–4 Hz in our case) is a difficult engineering challenge. This is due to the large air mass that must be moved to created useful signal levels. The fundamental simple source equation, which will govern almost any human-made infrasound source due to the long wavelengths, shows this fundamental difficulty. As frequency decreases, the volume velocity must increase by the inverse factor of the frequency decrease in order to maintain an equal pressure amplitude at equal range. In other words, 1000 times the cubic volume of air must be moved at 0.1 Hz as compared to 100 Hz, in order to maintain an equal output pressure amplitude! For this reason, a novel method has been proposed to skirt this engineering challenge; using the large energy density available in gas combustion for periodic thermal expansion of an air mass. This talk builds on previous work by the authors (Smith and Gabrielson, J. Acoust. Soc. Am. 137, 2407, 2015 and Smith and Gabrielson, J. Acoust. Soc. Am. 143, 1808, 2018) and presents comparisons of a 1st-order thermodynamic model and empirical measurements using a large liquid-propane burner system from a hot air balloon.
Modeling thermal effects in the time domain
Authors: Thompson Stephen C.
Published: October 2018

Modeling thermal transfer from fluid to a solid surface is well understood. However, the mathematical description of this behavior includes transcendental functions in the frequency domain. This precludes some kinds of modeling in the time domain. In some simple geometries, however, it has been shown that a continued fraction expansion of the transcendental functions is possible that allows for a finite bandwidth solution in the time domain. This paper will explore the use of these methods for time domain modeling of thermal-acoustic systems.
Phonetics, psycholinguistics, and language-specificity
Authors: Bradlow Ann
Published: October 2018

How does linguistic knowledge influence speech production, perception, and learning? In this presentation, I will review three sources of empirical evidence for language specificity in some of the most basic processes of speech communication. Each line of evidence will highlight the contributions of the remarkable Jongman-Sereno collaboration—the honorees of this special session—and their continuing influence on generations of students. First, we will consider language specific phonetics as it relates to the acoustic details of speech categories across languages with different sound inventories, including Modern Greek, German, English, and Spanish. Second, we will examine the influence of language background on speech perception through comparisons of pitch perception by speakers of languages with and without lexical tone. Finally, we will focus on speech training in adults when presented with novel speech patterns, asking in particular how general learning principles interact with language-specificity for perceptual adaptation to second-language or foreign-accented speech. In each of these domains—production, perception, and learning—we will see the expanding circles of interaction amongst Jongman, Sereno, and their many students and colleagues. Critically, these Jongman-Sereno contributions underscore the importance of cross-language comparison coupled with a highly collaborative research approach for understanding speech processing and learning.
Experience, attention, and context in the processing of systematic variation in spoken language
Authors: Nygaard Lynne C.
Published: October 2018

The acoustic speech signal is characterized by enormous variability. Characteristics of individual speakers and groups of speakers profoundly change the way in which linguistic structure is realized. A substantial body of research suggests that language users track, retain, and use systematic variation to restructure linguistic representation and processing in order to maximize intelligibility of spoken language. Less clear is whether sources of variation differ in relevance during speech processing and how relevance changes as a function of experience and context. Research will be presented examining talker-, task-, and listener-related factors that mediate memory and learning of systematic variation in spoken language. The findings suggest that although listeners dynamically adapt to systematic changes in linguistic structure as a function of experience, this adaptation depends on the characteristics and frequency of particular sources of variations, the modulation of attention driven by the structure of the learning environment, and expectations and subsequent sensitivity to socially relevant variation. The considerable behavioral and representational plasticity that is characteristic of speech perception and spoken language processing may depend in part on the social, linguistic, and contextual relevance of the variation associated with both individual talkers and classes of talkers.
What the /f/? We’re not done with fricatives yet. Integrating across time and frequency bands
Authors: McMurray Bob , Galle Marcus , Farris-Trimble Ashley , Seedorff Michael
Published: October 2018

Fricatives represent an extreme version of lack of invariance. This illustrated by Jongman, Wayland and Wong’s (2000) singularly comprehensive look at the acoustics of a set of speech sounds. They show that fricatives require dozens of cues; and each cue is affected by multiple context factors. Later work with this corpus solved these problems with simple models. But we’re not done yet. I present new studies that raise two additional problems highlighted by fricatives. First, listeners must integrate cues over long timescales: frication cues may arrive several hundred milliseconds before the vocoid. I present several experiments that used eye-tracking to determine when cues are used. Unlike, prior results with stops and vowels, they show evidence for an encapsulated memory buffer preceding lexical access—lexical decisions are delayed until both cues arrive. Second, for fricatives, listeners must integrate information across distinct frequency bands. This was highlighted in a study of hybrid cochlear implant users who integrate low frequency residual acoustic hearing with high frequency electric hearing. Unexpectedly, hybrid listeners performed worse on fricatives than those with only electric hearing. Thus, the problem of combining information across frequency bands may be suboptimally solved in acoustic + electric CI users, suggesting new principles of cue-integration.
Building a multilingual ultrasound corpus
Authors: Berkson Kelly , de Jong Kenneth , Lulich Steven M. , Cavar Malgorzata E.
Published: October 2018

This paper presents a corpus of three dimensional ultrasound data focused on tongue shape during speech sound articulation. Our ultimate goal is to collect data pertinent to phonetic structures from as many languages as possible (at present upwards of 20 languages are represented) and to curate these data in an open access corpus that is freely available for use by other researchers. In this presentation, we review the structure of the corpus and present a series of case studies illustrating the ways in which three-dimensional data are being used to address questions of phonetic interest. Examples of such areas include: examining the articulation of laterals; determining the point of articulation for dorsal consonants; analyzing consonant and vowel coarticulation patterns; and elucidating how coupling of the tongue body with the tongue blade and root affect place and manner of articulation. Like the work of Allard Jongman and Joan Sereno, this project is inherently collaborative and includes ample opportunity for using guided investigation of targeted research questions to ease novice scholars into the research process.
Linguistic experience and musical training in shaping Mandarin tone perception by trilingual non-native Cantonese listeners
Authors: Chen Si , Yang Yike , Wayland Ratree , Zhu Yiqing
Published: October 2018

Mandarin tones are perceived categorically by native listeners, but not by non-native listeners (e.g., Francis et al., 2003; Hallé et al., 2004; Xu et al., 2006). Vowel quality, stimulus duration, and language background also significantly contributed to categorical perception of tones among native and non-native listeners (Chen et al., 2017). In comparison to pitch production, it was found that a relative shorter duration is required to perceive than to produce pitch contours, with non-tonal listeners needing longer duration to detect a change in the pitch direction. Duration asserts a stronger effect on between- and within-category discrimination patterns among tonal listeners. Fewer studies investigated the effects of stimulus duration and vowel quality in trilingual non-native speakers with and without musical training. Our study examines categorical perception of resynthesized pitch stimuli by 13 trilingual Cantonese musicians and 13 Cantonese non-musicians. We manipulated tones on both low and high vowels ([a] and [i]) to create 7-step, level-to-falling and level-to-rising pitch continua on both [a] and [i] vowels with 9 different duration values. Cantonese speakers participated in identification and same-different tasks.
The effect of minimal neighbors on acoustic detail in the production or real and nonce words in Italian
Authors: Dmitrieva Olga , Celata Chiara
Published: October 2018

Previous research on English demonstrated that the existence of minimal neighbors in the lexicon can lead to the enhancement of the differentiating acoustic property, such as Voice Onset Time (VOT) in voiceless stops (Baese-Berk & Goldrick, 2009). In this study, the effect of minimal lexical neighbors (e.g., cara “dear” is a minimal neighbor for gara “match”) on the acoustic realization of voicing and gemination was examined in real and nonce words in Italian. Thirty native speakers of Tuscan Italian read one of the two stimuli lists, one containing only geminated and voiced stimuli and the other containing only singleton and voiceless stimuli, such that a given participant was never exposed to both members of a minimal pair. The results showed that real words with minimal neighbors had longer negative VOT if voiced or positive VOT if voiceless than real words without minimal neighbors. However, the existence of a real minimal neighbor did not affect VOT duration in nonce words. Analysis of nasal and voiceless stop geminates is ongoing.
Bilingual word familiarity in Cantonese and English
Authors: Cheng Lauretta , Johnson Khia A. , Babel Molly E.
Published: October 2018

Bilingual speakers are typically unbalanced in their vocabularies in each language, with each language’s lexicon being representative of the experiences and domains in which the bilingual uses that language. This can create a challenge in creating word lists for speech experiments, as the frequency counts from publicly available corpora do not represent the appropriate vocabulary domains. In this paper, we report on a word familiarity rating task in Cantonese and English that was designed to pretest stimuli in both languages to confirm the items were matched in familiarity for use in subsequent speech tasks. Participants fell into four different groups: Cantonese-English bilinguals who grew up in a Cantonese-dominant location, Cantonese-English bilinguals who grew up in an English-dominant location, North American English speakers with no Chinese language experience, and international English speakers with no Chinese language experience. All listeners were presented with blocks of Cantonese words/nonwords and English words/nonwords and were asked to rate the familiarity of each item. We compare these ratings across participant groups and in relation to corpora for each language to assess how the listener groups perform. We discuss these results in the context of designing stimuli lists that are appropriate for diverse, multilingual populations.
Adaptation of native clusters with non-native phonetic patterns
Authors: Kwon Harim , Chitoran Ioana
Published: October 2018

Non-native consonant clusters are modified to conform with native phonotactics. This study investigates how onset clusters that are phonotactically licit, but have non-native phonetic patterns, are adapted to match the native patterns. We tested Georgian speakers in a sentence completion task using CCV/CVCV sequences produced by a French talker. Georgian differs from French in having (1) longer inter-consonant timing lag for CCVs, and (2) default initial prominence for CVCVs. The long inter-consonantal lag often results in a transitional vowel in Georgian. Georgian participants (n = 11) first saw the target CCV/CVCV sequences embedded in a Georgian carrier phrase and read the phrase aloud (baseline). Then they heard the target sequences produced by a French talker while seeing the Georgian carrier phrase with an empty slot, and produced the phrase completed with the heard targets (test). Participants' test productions reflected modifications of French targets towards their native phonetic patterns, not only by producing occasional transitional vowels that are absent from French CCV targets, but by deleting the unstressed first vowel in French CVCVs (/pøta/ produced as /pta/). We claim that the effects of native language on adaptation of non-native sequences are not limited to their segmental composition, but also involve their phonetic implementation.