bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of surface scattering of very high frequency acoustic signals
Authors: Preisig James , Deane Grant
Published: November 2016

Many applications of acoustics in harbors are characterized by relatively shallow sources and receivers and a sound speed profile that does not strongly refract signals away from the surface. Therefore, surface scattering is an important factor in determining the characteristics of propagating signals in harbor environments. In addition, applications often involve relatively short propagation distances so very high frequency (VHF) acoustic signals, defined here to be signals above 100 kHz in frequency, can be important components of acoustic systems in harbor environments. These VHF signals have very short wavelengths (approximately 2.7 mm at a frequency of 550 kHz) so surface waves as small as capillary waves can have a significant impact on the surface scattered signals. Thus, even in light wind and wave conditions, the surface scattering of VHF can be highly dynamic. A test of the surface scattering of acoustic signals between 350 kHz and 750 kHz by wind-driven waves was conducted in a wave tank with the received signals being recorded at a vertical line array. This talk will present the analysis of the characteristics of the surface scattered signals including their spatial structure and Doppler spreading and the periodicity of their temporal fluctuations.
Acoustic monitoring of the bottom characteristics of a harbor
Authors: de Moustier Christian
Published: November 2016

Acoustic monitoring of the underwater environment typically found in a harbor requires knowledge of the spatial and temporal variability of the noise, the water properties, the currents, and the bottom characteristics. For safety of navigation, repeat bottom surveys must be performed at regular intervals to monitor changes in water depth along navigation channels due to accumulation or depletion of sediments, and to detect potential hazards on or near the bottom. Imaging side-looking sonars, particularly those with synthetic aperture capabilities, are most effective for hazard detection but their performance in waters 5-10 m deep can be hampered by multipath and by changes in water properties at the scale of the scene being imaged. Their inherent spatial filtering characteristics make multibeam echosounders effective tools for synchronous bathymetry and acoustic backscatter imagery of the water column and the bottom. In harbor surveys, such echosounders achieve decimetric spatial resolution by operating at several hundred kilohertz, but their measurements are sensitive to spatial and temporal changes in water properties at the scale of the survey swath, potentially reducing lateral coverage. The corresponding variations in acoustic absorption affect acoustic backscatter imagery and yield increased uncertainty in the outcome of a repeat harbor survey.
Diffusion: Better ways of measuring it, displaying the data and using it in room simulations
Authors: Sauro Ronald
Published: November 2016

This paper will present and discuss diffusion and the many problems with trying to measure it, displaying the data and using this data in ways that allow us to better predict room responses. We will quickly discuss prior standards, their strengths and weaknesses and how a new proposed ASTM standard will correct those weaknesses. We will show that methods used in other areas of acoustics and electro-acoustics can be used to measure diffusion and display it in ways that allow directivity, magnitude, and phase to be displayed. These data sets can then be used in simulation programs, such as EASE. Odeon and CATT Acoustics, to better predict room responses for use in the design of rooms. We will present examples of those uses and the advantages in these proposals.
Designing of variable Schroeder diffusers using digital architecture techniques
Authors: Azad Hassan , Siebein Gary
Published: November 2016

Schroeder diffusers consist of a series of wells of the same width and different depths. The wells are separated by thin fins. The depths of the wells are determined by a mathematical number sequence, such as the quadratic residue sequence. The sequence number for the nth well, Sn, is given by1: Sn = n2modulo N where modulo indicates the least non-negative remainder and is often written as mod for short. N is the number generator which in this case is also a prime and the number of wells per period. The well width follow the simple equation as follow in which λmin is the minimum wavelength before cross-modes in the wells appear1: W = λmin / 2 In this paper it is intended to build a physical model of a N = 7 diffuser and make the depth of each well separately variable by means of digital architecture tools. The tools which is referred to would be Arduino kit micro controller and 7 stepper motors and 7 drivers. The idea behind this practice is twofold. First is to come up with a variable diffuser which works in several (preferably 5) design frequencies and hence their integer multiples. The user can make this adjustment via a simple computer program. Second, to try other mathematical number sequence and observe the diffusion characteristics of new products using the analyses of acoustic measurement results. 1. Acoustic Absorbers and Diffusers Theory, Design and Application, T. J. Cox and P. D’Antonio, 2nd ed.
Spatialized sound reproduction for telematic music performances in an immersive virtual environment
Authors: Chabot Samuel
Published: November 2016

Telematic performances connect musicians and artists at remote locations to form a single cohesive piece. As these performances become more ubiquitous as more people have access to very high-speed Internet connections, a variety of new technologies will enable the artists and musicians to create brand new styles of works. The development of the immersive virtual environment, including Rensselaer Polytechnic Institute's own Collaborative-Research Augmented Immersive Virtual Environment Laboratory, sets the stage for these original pieces. The ability to properly spatialize sound within these environments is important for having a complete set of tools. This project uses a local installation to exemplify the techniques and protocols that make this possible. Using the visual coding environment MaxMSP as a receiving client, patches are created to parse incoming commands and coordinate information for engaging sound sources. Their spatialization is done in conjunction with the Virtual Microphone Control system, which is then mapped to loudspeakers through a patch portable to various immersive environment setups.
Essential details in performing art facilities' practice rooms
Authors: Nelson Smid Jennifer
Published: November 2016

Limited space and multi-use programming often leaves practice rooms working for several instrumental and vocal groups within performing arts facilities. During programming, communication about expected performance of the space and adjacencies, as well as design team collaboration will help to keep the project in scope and on budget. Special details for multiple trades are required to design a well isolated and multi-functioning practice room for various quantities and ranges of instruments and voice. The details are important not only throughout the design phases but must be carefully observed during build-out so that special isolation requirements are incorporated correctly. The entire process from design, detailing, and into construction is presented with emphasis on the various communication processes required to arrive at successful outcomes. Specific examples are provided highlighting the importance of each step in the process.
Silent Room: A (non)sensory interactive art installation
Authors: Zeh Matthew C. , Cheung Fiona , Heijdens Simon , Wilson Preston S.
Published: November 2016

Simon Heijdens, a London-based Dutch artist, was commissioned by South by Southwest (SXSW), an annual film, media, and music festival in Austin, TX, to create an installation artwork to premiere at SXSW in March 2016. In reaction to the sensory overload of the festival, he created Silent Room. Students and professors from the University of Texas at Austin worked alongside Mr. Heijdens to design a portable, self-sufficient, reusable space providing sound isolation and absorption from outside and inside the chamber, respectively. Housing the space in a shipping container, Silent Room was successfully built and showcased at SXSW in downtown Austin to hundreds of visitors, achieving a minimum sound reduction of 27 dBA at 40 Hz and a maximum reduction of 55 dBA at 1.45 kHz. These results were achieved using a suspended floor and decoupled wall/ceiling construction of Auralex rubber U-Boats, 2” x 4” wood studs, mineral fiber insulation, plywood, Auralex SheetBlok vinyl, and acoustically treated gypsum board. After initial acoustical measurements, more U-Boats were added, decoupling the container underside from the street and isolating it from ground-borne vibration. However, the room performance worsened after this change, possibly due to exposure to a new air-borne path for noise ingress.
Fin whale song patterns in Southern California and the Gulf of California
Authors: Sirovic Ana , Oleson Erin M. , Buccowich Jasmine S. , Rice Ally
Published: November 2016

The most common fin whale calls, 20 Hz pulses, are often produced in regular, stereotypic sequences termed songs. The main variability in songs comes from the differences in the duration of the interval between successive pulses, the interpulse interval (IPI). Data recorded between 2000 and 2012 in Southern California and 2004 to 2010 in the Gulf of California were analyzed for temporal and geographic patterns in fin whale songs. During this time, fin whales in Southern California and the Gulf of California produced four song types with distinct IPI sequences. Two common songs in Southern California were the short doublet and the long doublet and they were detected year-round. The IPIs in the short doublet song have been increasing over the long term, while the IPIs in the long doublet song showed no long-term trends but were seasonally variable. In the Gulf of California, the most common songs were the short triplet and the long triplet. These songs were detected in Gulf of California year-round, although their occurrence decreased August through October. There was some exchange of sons between the two areas that might point to seasonal movement of parts of these populations.
Fin whale occurrence and population structure in the central and western Pacific through detection and characterization of song patterns
Authors: Oleson Erin M. , Širović Ana , Rice Ally , Varga Leah M.
Published: November 2016

Fin whale songs comprise series of 20Hz pulses and song structure can be characterized by patterns of inter-pulse intervals (IPIs). Recent studies in the northeast Pacific indicate the occurrence of a broadly distributed, seasonally changing, but annually stable IPI pattern, heard from the Bering Sea to southern California and west to Hawaii. Other geographically localized song patterns are also known in the Gulf of California, the Bering Sea, and off southern California. We expanded the assessment of fin whale song across the Pacific, analyzing occurrence and song patterns from multi-year passive acoustic data collected at several sites in the central and western Pacific, from Palmyra Atoll to the Northwestern Hawaiian Islands and west including Wake Atoll and the Mariana Archipelago. Fin whales are relatively uncommon in these tropical and sub-tropical waters, though they are detected in all seasons at some sites. Song IPI patterns suggest multiple and potentially annually variable fin whale song structures throughout the region. The common northeast Pacific song is heard at Hawaii and Wake Atoll sites, with different song types at Palmyra and in the Mariana Archipelago. Long-term temporal and geographic patterns of song occurrence across the region will be discussed.
Comparison of three Stenella spp. audiograms measured using auditory evoked potentials and behavioral methods
Authors: Greenhow Danielle R. , Cardwell Adrienne , Powell Jessica R. , Hill-Cook Mandy L. , Stamper M. Andrew , Byrd Lynne , Manire Charles A. , Brodsky Micah C. , Bauer Gordon B. , Mann David A.
Published: November 2016

The oceanic dolphin genus Stenella is underrepresented in cetacean hearing data. In this study the hearing of three Stenella spp. dolphins was measured using auditory evoked potential (AEP) methods. A single male juvenile Atlantic spotted dolphin (Stenella frontalis) was rehabilitated in Key Largo, Florida, after being sighted alone and emaciated. The Atlantic spotted dolphin’s greatest sensitivity was at 40 kHz, with functional hearing up to 128 kHz. A female spinner dolphin (Stenella longirostris), housed at Mote Marine Laboratory, had peak sensitivity at 40 kHz and functional hearing up to 120 kHz, the highest frequency tested. The sensitive high frequency hearing of the spinner and Atlantic spotted dolphin is similar to that found in other oceanic odontocetes. A pantropical spotted dolphin (Stenella attenuata) was housed at Mote Marine Laboratory and hearing thresholds were determined using AEP and behavioral methods. The pantropical spotted dolphin had a peak sensitivity at 10 kHz, with a cutoff frequency between 14 and 20 kHz. The source of the dramatic high-frequency hearing loss is not known; possible causes include congenital hearing loss (present at birth) or hair cell death due to treatment with ototoxic drugs during rehabilitation.
Human listening experiments provide insight into cetacean auditory perception
Authors: DeLong Caroline M.
Published: November 2016

Odontocete cetaceans produce an array of sounds including echolocation clicks that can be used for object recognition and whistles used primarily for communication. Echoes and whistles contain a multitude of acoustic features, and the salient features used by animals when identifying objects or in social contexts are often difficult to isolate. One method for detecting salient acoustic features is to compare the performance of cetaceans and humans on the same auditory perception tasks. Human listeners can be presented with echoes produced with simulated cetacean clicks or whistle-like stimuli and provide verbal feedback on discriminatory cues. An early human listening study was performed by Au and Martin (1989). Seven studies performed over the past 15 years show that humans perform as well or better than cetacean subjects in a variety of tasks: echoic discrimination of objects varying in size, shape, material, texture, or wall thickness; echoic recognition of objects from various aspect angles; echoic object discrimination using clicks from different cetacean species; and recognition of frequency-modulated whistle-like sounds. Analyzing the error patterns of humans and cetaceans alongside the reported cues reveals processing mechanisms and decision strategies cetaceans may use. This comparative approach sheds light on how cetaceans perceive and represent sounds.
Acoustic processes in an echolocating bottlenose dolphin’s (Tursiops aduncus) head using a finite element model
Authors: Wei Chong , Au Whitlow W. , Song Zhongchang , Ketten Darlene R. , Zhang Yu
Published: November 2016

Bottlenose dolphins (Tursiops aduncus) are a well-known species using broadband echolocation signals for searching prey and spatial orientation. In this study, the computed tomography (CT) scan data were obtained to set up a two-dimensional finite element model. In the vertical plane, the acoustic field on the animal’s forehead and the far field transmission beam pattern of an echolocating dolphin were calculated. The simulation results and prior measurement results were consistent qualitatively. The role of the main structures on the sound propagation pathway such as air sacs, melon, skull, and connective tissues was investigated. Furthermore, the signal at the source excitation was investigated. It suggested that the broadband echolocation dolphins may not have the same driving signals at the source excitation as the narrowband echolocation dolphins. The results can help us gain further understanding of the acoustic processes in dolphin’s biosonar.
Multi-species Baleen Whale audiogram modelling
Authors: Ketten Darlene R. , Zosuls Aleks , Tubelli Andrew
Published: November 2016

In this research, we produced model audiograms for two Mysticetes (baleen whales) that are among the species most likely to be subject to impacts from common lower frequency anthropogenic sound sources deployed in the oceans. These models are needed for species-specific risk assessments for hearing impacts, for determining optimal signals for playback experiments, and for determining effective electrode and sound source placements for auditory brainstem response (ABR) measures in live stranded whales. We employed micro and UHRCT, dissection, and histology of minke (Balaenoptera acutorostrata) and humpback (Megaptera novaeangliae) heads and ears to calculate inner ear frequency maps for determining total hearing range, the frequency of peak sensitivity, and the probable frequency of NIHL liability (“notch”). The anatomically derived data were then combined with direct measures via nanoindentation of middle ear stiffness, Young’s modulus, frequency response, and inner ear stiffness to determine the middle ear transfer function and basilar membrane stiffness gradients. FEM simulations were employed to further explore the responsivity of the tympanum and middle ear ossicular chain. In order to test the validity of the model techniques, model audiograms were produced also for two odontocetes, the bottlenose dolphin and the harbor porpoise, and compared with well-established behaviorally obtained audiograms for these species. [This research was supported by the LMR and JIP marine research programs.]
Discrimination of natural from synthetic ultrasonic vocalizations by laboratory mice
Authors: Kobrina Anastasiya , Screven Laurel , Dent Micheal
Published: November 2016

Mice produce spectrotemporally complex ultrasonic vocalizations (USVs) which are thought to be important for mate attraction, courtship, and other social interactions. Despite this assertion, little is known about how mice perceive or use these auditory signals. USVs have been categorized based on a variety of spectrotemporal parameters, including frequency, amplitude, and duration. Previous studies have established that mice are capable of detecting and discriminating natural, synthetic, and altered USVs using physiological and behavioral methodologies. The current research examined whether mice are capable of discriminating natural USVs from their synthetic analogs. Discrimination performance was tested in six adult mice using operant conditioning procedures with positive reinforcement. Discrimination was high for some USV categories but low for others, suggesting that more than simple spectrotemporal similarity is involved in the discrimination of USVs.
Emergence density and stream frequency spectra of Tadarida brasiliensis
Authors: Dreessen Stephanie , Mardis Cassi , Kloepper Laura
Published: November 2016

Bats depend on echolocation to maneuver through their environment. Mexican Free-Tailed bats (Tadarida brasiliensis) form large maternal colony roosts and emerge in large, dense groups. Previous work found that the T. brasilensis bats adjust their call structure during emergence, which may help the bats avoid flight collisions. The limited physical space between bats in the emerging stream is not only problematic with flight collisions, but also with echolocation interference. In this study, we tested how the density of emergence affects echolocation. Specifically, we tested the hypothesis that the density of flying bats affects echolocation characteristics of the entire stream. We determined six emergence density categories from thermal imagery, and randomly selected 20, 500 ms audio samples corresponding to each density. For each audio sample, we calculated the frequency spectrum, and analyzed how the stream frequency spectrum changed according to population density. Across densities, the stream frequency spectra all have the same shape and peak frequencies, but the variance for certain frequencies differs. This change in variance suggests that these bats are attempting to avoid jamming in dense emerging streams by altering their frequencies from bat-to-bat, irrespective of density.
Sound localization of fish calls recorded by two stereo-underwater-recorders
Authors: Yamato Kazuki , Matsuo Ikuo , Takahashi Ryuzo , Matsubara Naoto , Yasuma Hiroki
Published: November 2016

Some fish produce sounds during the spawning and ramping behaviors. These sounds have been used for discrimination of fish species. Recently, the method was proposed to estimate the direction of fish call by using the arrival time difference between two hydrophones. However, it was difficult to estimate sound localization in the case of using the measured data from two hydrophones, that is, one stereo recorder. In this presentation, we used two stereo recorders, including four hydrophones for sound localization. The sound data were measured during spawning at fish, Hexagrammos otakii, in the littoral region of Usujiri-cho, Hakodate, Hokkaido, Japan (N41°56'11", E140°56'41"). First, the fish calls were automatically detected by using the sound features including duration, max frequency, and amplitude. These features were determined by analyzing the sound data manually. Second, the arrival directions of detected fish calls were estimated in terms of each stereo recorder. Then, the fish calls were localized by using two arrival directions. As a result, it was clear that there were fishes producing call sounds around the spawning bed.
Generation of different types of surface acoustic waves by shock wave-Stone interaction
Authors: Zhang Ying , Yang Chen , Zhong Pei
Published: November 2016

The generation of different types of surface acoustic waves (SAWs) in lithotripsy is investigated by numerical simulations using COMSOL, considering either the case of a weakly focused shock wave as an incident plane wave (in the focal plane) in shock wave lithotripsy (SWL) or a spherically divergent shock wave produced by a spark discharge in Nano Pulse Lithotripsy (NPL). The interaction of these two types of shock waves with an artificial kidney stone immersed in water may generate three different types of SAWs: namely, Scholte wave, acoustic surface evanescent wave (ASEW), and leaky Rayleigh wave (LRW). In particular, we examined the generation of SAWs on a flat, cylindrical, or spherical surface under different incident angles. It was found that the geometry and acoustic properties of the stone could significantly influence the types of SAWs generated and the resultant peak tensile stress produced at the stone-water boundary. Comparison with experimental measurements (i.e., Schlieren and photoelastic imaging) and stone fracture will also be made. [Work supported by NIH through 5R37DK052985-20.]
An ultrasound guided monitoring system for high intensity focused ultrasound and radio frequency ablation therapies
Authors: Kondo Ryosuke , Koizumi Norihiro , Tomita Kyohei , Kayasuga Atsushi , Nishiyama Yu , Tsukihara Hiroyuki , Fukuda Hiroyuki , Numata Kazushi , Matsumoto Yoichiro , Mitsuishi Mamoru
Published: November 2016

In accordance with the progress of the HIFU (High Intensity Focused Ultrasound) and RFA (Radio Frequency Ablation) treatments, the intensity of the focal lesion and the surrounding marginal area changes little by little. Here, it should be noted that the human eyes are very weak when the image takes a long time to change even if the image change from the start of the ablation treatment is large. To cope with those problems, we propose an ultrasound guided monitoring system to evaluate the progress of the ablation therapy quantitatively in order to secure the certain level of the monitoring during the HIFU and RFA therapies by reinforcing the lack of experience of medical doctors. Particularly, we propose a system to monitor and evaluate the intensity of the focal lesion and the intensity of the surrounding marginal area by tracking the position of the characteristic texture area near the focal lesion, which moves in accordance with the respiration. Our method to overlay the focal lesion and the surrounding marginal area on the ultrasound image is also effective in order not to miss the area to be treated. The experimental results during RFA ablation therapy shows the effectiveness of our constructed system.
Directivity control of a graphene loudspeaker array using elementwise switching technique
Authors: Kim Dong-Hwan , Choi Jung-Woo
Published: November 2016

Graphene is a promising material for thermoacoustic transducers because of its low heat capacity per unit area and easy fabrication process. In contrast to the conventional voice-coil loudspeaker, a small thermoacoustic loudspeaker can produce omnidirectional radiation even without enclosures. In addition, the sound level from a thermoacoustic loudspeaker is less sensitive to its radiating surface area, which makes it an ideal omnidirectional sound source in high frequency region. In this work, we present an elementwise switching control of a graphene loudspeaker array utilizing the advantages of thermoacoustic loudspeakers. With an array of 3D graphene transducers, a directivity is controlled by polarity switching of each element according to a pre-determined pattern. A single channel input signal is modulated into two different channel signals using a polarity inverter. Each graphene element is driven by the same signal with different sign, and the polarization pattern of the array forms a designated beam pattern. The proposed technique simplifies the control of beam patterns without using large number of independent channels, and hence, enables the construction of a high frequency driver with variable-directivity.
Open loop active control of noise through open windows
Authors: Shi Chuang , Murao Tatsuya , Shi Dongyuan , Lam Bhan , Gan Woon-Seng
Published: November 2016

Noise propagating through open windows is a big concern of liveability in metropolises, where residential buildings and main roads are built densely. Active noise control (ANC) is a convincing technique to improve the current situation. Classic ANC systems adopt the close loop control. The quietness after control is continuously monitored by error microphones. However, ANC systems that attenuate noise propagating through open windows should ideally avoid the use of error microphones for the ease of implementation and maintenance. Furthermore, as open windows are commonly large as compared to the wavelength of noise, multichannel ANC systems are necessary to be carried out. They result in huge computational burdens that cannot be handled by low-cost hardware platforms. This paper investigates acoustic characteristics of open windows and formulates the control strategies as a spatial sampling and reconstruction problem. This theoretical development prompts the fact that controlling noise propagating through open windows essentially leads to global noise reduction. Both centralized and decentralized open loop control are feasible to deal with broadband noise. The upper bound of the effective band is limited by the spacing between channels, while the lower bound is dependent on the frequency response of secondary sources.
Physics girl experience—Using YouTube to teach acoustics and wave physics
Authors: Cowern Dianna L.
Published: November 2016

YouTube is usually considered an entertainment medium to watch cats, gaming, and music videos. But educational channels have been gaining momentum on the platform, some garnering millions of subscribers and billions of views. The Physics Girl YouTube channel has focused solely on physics education. Using this channel, we can examine the ways that educational channels grow, their demographical reach, how they are utilized, and how online media and technology can facilitate good and bad learning. YouTube provides unique access to a wide audience. The videos can vary in length and purpose—from tutorials to classroom supplements. In addition, the online world provides the ability to organize and serve educational communities, like PBS Learning Media. With all these tools available, Physics Girl aims to introduce physics as related to real-world examples and interesting questions that are not always covered in traditional teaching. While the goals of each channel vary, each aims to contribute to better STEM learning.
Voices of Hawai'i's rhythmic world
Authors: Marzan Marques H.
Published: November 2016

Hawai'i is home to a myriad of musical instruments made from a variety of materials, which include stone, wood, gourd, and shell. The resonance that each produces, complements the transmission of knowledge within the Hawaiian culture, through storytelling, dance, and song. Both the secular and spiritual worlds harness the energy these instruments produce, infusing ceremony and daily life with the voices of the uncountable manifestations of akua, the gods. The material choices used in the creation of Hawaiian instruments connect the realm of man to the realm of the gods, as all animate and inanimate materials represent a kinolau, the physical manifestation of the pantheon of Hawaiian gods. The relationships that are forged with our surroundings, through these tools, allow us a glimpse into a world of endless possibilities.
Calculating scale tunings of Polynesian nose flutes
Authors: Hoekje Peter L.
Published: November 2016

The Polynesian nose flute is found in two versions that are blown in a similar manner but fingered and tuned differently. The Eastern Polynesian flute, known in Hawai'i as 'ohe hano ihu, but is found also to Tahiti and Niue. The tube is closed by a segment node at one end but with a hole for blowing and open at the other end. It typically has two or three finger holes along the tube and three or four playable notes. Being similar to other flutes, the scale tunings can be calculated from hole and tube dimensions by analytic expressions. In Fiji, New Zealand, Samoa, and Tonga, where it is known as fangufangu, both ends of the Western Polynesian flute are closed by segment nodes. There are five holes are placed along the top, usually evenly spaced from one end to the other, with a sixth hole in the middle underneath, giving a variety of fingering options with four to six notes and two registers. The scale tunings are determined by first calculating the frequency response using a lumped-element method.
Characterization of low frequency sounds emanating from entertainment venues
Authors: Woolworth David S.
Published: November 2016

The advent of inexpensive low frequency reproduction for audio has changed the way modern popular music is composed and recorded; these inexpensive systems are more common than ever in clubs (and vehicles), which has a direct effect on the soundscape resulting from high sound level playback and limited sound attenuation for low frequencies in typical building structures. This paper characterizes the low frequency content of sounds propagated intra-building, inter-building, and to the outside from various entertainment venues from the perspective of both frequency and time. Additionally, the paper will discuss suggested techniques for testing venues under controlled situations with pre-recorded and live sound sources to augment testing based on standards.
Wind-induced noise in a convective boundary layer
Authors: Hart Carl R. , Wilson D. K.
Published: November 2016

Wind-induced noise, as sensed by a screened microphone in the atmosphere, produces a highly varying noise floor. At low frequencies, this noise source may dominate the ambient noise spectrum and present a challenge for signal detection. The sensed noise is affected by several factors in the atmospheric convective boundary layer: the mean flow at the height of the microphone, turbulent eddy interaction with the windscreen, and pressure fluctuations within the turbulent flow. Recently, van den Berg (2006) compared measured wind noise to modeled spectra. In that study, several meteorological variables were inferred from fits of modeled wind noise spectra rather than from meteorological observations. If additional meteorological observations are collected, then it may be possible to conduct model validation. In addition to temperature, pressure, and wind velocity, the surface roughness length for momentum and the vertical temperature flux must be observed. Recent models of turbulent wind velocity, in the convective boundary layer, suggest that the planetary boundary layer height may also be an important variable for wind-induced noise. This study analyzes data collected in the Southwestern United States during a 2007 long-range sound propagation experiment. Wind noise data are compared against concurrent meteorological data and several wind-induced noise models.
In situ nonlinear ultrasonic probing during plastic deformation
Authors: Espinoza Carolina , Salinas Vicente , Mujica Nicolás , Lund Fernando
Published: November 2016

In is well known that nonlinear ultrasound is sensitive to micro-structural changes in materials. Here, we present recent results obtained during tensile tests of aluminum samples. Using continuous ultrasonic waves, we study the second harmonic generation and its relationship with dislocation proliferation during plastic deformation. The experimental setup is based on two transducers, an emitter and a receiver, both coupled face to face to a probe mounted on a standard tensile test machine. We measure both the first and second harmonic received amplitudes, Aω and A2ω respectively, for several amplitudes of the emitted signal. These are related by a nonlinear parameter β, through A2ω = βAω2. We observe that β is independent of the applied stress during the elastic regime, whereas it presents strong variations once plasticity occurs, presenting a pronounced maximum before fracture. This maximum can be considered as a signature, a warning, of a fracture that is soon to come.
Using elastic nonlinear modulation of sound by sound to detect fracture orientation in reservoir rocks
Authors: TenCate James A. , Malcolm Alison E. , Fehler Michael C.
Published: November 2016

Cracks play a key role in our ability to produce oil and gas or monitor water resources, from microscale cracks that enable permeability in tight formations to larger faults and fractures that compartmentalize reservoirs. Our ability to sense and understand cracks is thus of key importance. We explore the role that cracks play in the nonlinear interaction of propagating waves using an elastic version of modulation of sound by sound. We present a laboratory experiment in which a strong S-wave slightly changes the velocity of a lower amplitude P-wave, and use a rock sample with aligned fractures to demonstrate that this signal is strongly dependent on fracture orientation. We build on the linear slip theory to show that the propagating S-wave is indeed able to open the cracks that the P-wave velocity will be most sensitive to. This gives firm, direct evidence that cracks are a controlling factor in the nonlinear elastic properties of rocks, and opens up the possibility of using such signals to remotely map fracture orientations.
Acoustic emission due to partial cavity shedding on a hydrofoil
Authors: Wu Juliana , Ganesh Harish , Ceccio Steven
Published: November 2016

The partial cavity shedding dynamics on a NACA 0015 hydrofoil were examined at angles of attack of 7 and 10 degrees over a range of cavitation numbers. Hydrophone measurements in conjunction with high-speed videos and time resolved X-ray densitometry were used to acquire time synchronous measurements of the void fraction field of the cavity and the emitted noise. Cavitation dynamics changed significantly with the reduction of the inlet cavitation number. At higher cavitation numbers, small stable partial cavities were observed. Upon reduction of cavitation number, the cavities grew in length and pinched off from the rear of the cavity, due to a liquid re-entrant jet. Upon further reduction of inlet cavitation number, the dynamics changed significantly with the cloud collapse of the shed vapor inhibiting the cavity growth. X-ray densitometry measurements revealed the presence of a propagation bubbly shockwave as a mechanism of shedding at the lowest cavitation numbers. This process caused complex, multi-step cavity dynamics. Spectral analysis of the acoustic signal showed there were multiple acoustic frequency peaks, instead of a single well-defined shedding frequency. Spectral content of the acoustic measurements was then analyzed to identify different flow processes responsible for their generation.
Recognition of foreign-accented words in isolation
Authors: Mohamed Mirrah Maziyah , Abrahamyan Hayk
Published: November 2016

Foreign-accented speech presents a challenge for native speakers of a given language. When presented with foreign-accented speech, native speakers tend to rely heavily on context and other lexical cues. When processing isolated spoken words, participants do not have access to contextual cues and have to rely solely on acoustic cues. Thus, processing accented spoken words in isolation might be a bigger challenge. We tested the hypothesis that identification accuracies by native speakers of American English of two foreign-accented speakers with different accent strengths will not differ in isolated spoken word recognition task. Ten native speakers of American English rated the accent of a Chinese-accented (heavy accent) and a Korean-accented (moderate accent) speakers after hearing a small passage read by both speakers. Different set of native speakers of American English heard a list of isolated words spoken by both speakers and had to type what they had heard. Overall, participants did not differ in their accuracy in the identification task even though the speakers differed in the strength of their accent, while there was no significant difference in participants rating of the strength of the speakers’ accents. Implication of the results on the processing of foreign-accented speech will be discussed.
Non-native speakers perform poorer than native speakers in Japanese speech recognition in reverberation
Authors: Osawa Eri , Arai Takayuki , Hodoshima Nao , Igeta Takako
Published: November 2016

Reverberation affects perceptual performance, especially non-native listeners, elderly people, and people with hearing impairments. Native Japanese speakers confused some Japanese consonants and they failed to distinguish Japanese length contrast in reverberation [Arai et al., Proc. Autumn Meet. Acoust. Soc. Jpn., 2016]. The current study examined degradation degree of non-native speakers (native English speakers) in Japanese speech recognition in reverberation, using the same experiment settings with the previous study. There were two sets of stimulus: 1) Japanese consonant-vowel (CV) syllables, 2) non-words varying in duration of a certain vowel/consonant along durational continuum. In the results, although non-native speakers confused consonants even in non-reverberant condition, the number of their confusion in reverberation was larger than that in non-reverberant condition. Confusion of non-native speakers in reverberation was much more than that of native speakers. In addition, the results indicated that non-native speakers could hardly distinguish the length contrast of Japanese in reverberation. The proportion of “long” responses did not change sharply in the perception of vowel continuum, while native speakers changed their responses at some points on the continuum. The results suggest that learners need training for listening to speech sounds in reverberation.
Phonotactic knowledge and phonetic details in the perception of non-native consonant sequences: Evidence from Mandarin Chinese
Authors: Guan Qianwen , Kwon Harim
Published: November 2016

Previous research has shown that non-native consonant sequence perception is influenced by both the phonotactic knowledge of native language and the phonetic details of the stimuli. To further examine the effects of these two factors, we conducted two perception experiments with monolingual Mandarin listeners. In experiment 1, the listeners determined whether they heard a vowel between two consonants. Stimuli were VC1C2V with various intervocalic consonant sequences produced by a Russian speaker. The listeners reported hearing a vowel between two consonants (56%), providing evidence for the effects of native phonotactics. We also found that duration of C1 release influenced the perception of epenthetic vowel. In experiment 2, the same participants heard the non-native sequences in word-initial and intervocalic positions and transcribed them in Pinyin. 75% of the transcription data showed a vowel epenthesis. In addition, different strategies were observed in different positions in a word: word-initial position showed more C1 deletion presumably due to weak acoustic cues of C1 and intervocalic position showed more C2 deletion. Taken together, these findings indicate that while the native phonotactics play a dominant role in Mandarin listeners’ perception of non-native consonant sequences, the effects of phonetic details of the stimuli are not negligible.
Lexical age of acquisition effects on native and non-native speech perception
Authors: Kemp Renee
Published: November 2016

Lexical difficulty has been shown to play a role in both speech production and perception. The relative difficulty of a word can be determined based on lexicon properties such as usage frequency, neighborhood density, or lexical Age of Acquisition (AoA). These factors have been shown to predict a range of different acoustic modifications such as hyperarticulation and increased duration. The current study investigates the effect of AoA-conditioned phonetic variation in both plain and foreigner-directed speech conditions on both native and non-native English speech perception. 60 total subjects completed a lexical decision task. Investigating these two populations allows for an examination of the role of lexical difficulty in language acquisition. The data show that lexical AoA influences the accuracy of lexical decision responses. Specifically, native speakers were more accurate in their identification of words with a low AoA rating compared to a high AoA rating (i.e. more lexically difficult items). Interactions between AoA and speech condition were also observed. The findings of this study suggest acoustic modifications can serve, at least in part, to facilitate the perception of lexically difficult words.
Comparative acoustic analyses of non-native English: The search for systematic variation
Authors: Laturnus Rebecca
Published: November 2016

Previous research has shown that exposure to multiple foreign accents facilitates adaptation to an untrained novel accent (Baese-Berk et al. 2013). The explanation offered is that L2 speech varies systematically, such that there are commonalities in the productions of non-native speakers, regardless of their language background (e.g. L2 speech is slower and many of English's contrasts are difficult for speakers of other languages). The current work conducted a systematic acoustic comparison between two native English speakers and six non-native accents that closely matched those used in Baese-Berk et al. (2013). All talkers, taken from the Wildcat Corpus, were male, and the non-native voices had comparable foreign accentedness ratings (Van Engen et al. 2010). VOT and formant values of stressed and unstressed vowels were analyzed, comparing each non-native accent to the native English talkers. Additionally, pairwise variability indices were calculated for vocalic and consonantal intervals as measures of rhythm. The results for each measure show substantial variability across speakers, reflecting phonetic transfer from individual L1s, rather than commonalities in their productions. The data are therefore more consistent with a hypothesis of accent attunement wherein variability causes listeners to relax their expectations of what constitutes a good category exemplar.
The effects of second language experience on the perception of native language prosody
Authors: Oh Grace E.
Published: November 2016

The effects of second language experience on adult learners’ perception of native language prosody were investigated. A total of 39 sentences produced in Korean, Mandarin, Japanese by three female speakers were low-pass filtered and presented to three groups of 10 participants with different language backgrounds: Native Korean speakers with no L2 experience (NK group), native Mandarin speakers (NM group) and Korean learners of Chinese (KC group) with an average LOR in China of 1 year. The participants were instructed to listen to each stimulus and decide whether it was Korean or not based on the suprasegmental features. Overall, the NK group (76%) revealed significantly higher discrimination accuracy than the KC (65%) or the NM group (57%). However, the NM participants with extensive Korean experience showed significant improvement in accuracy for both Korean (75%) and Chinese (84%). The results, on the one hand, support the significant effect of L2 experience on the acquisition of L2 prosody. The KC group’s lower accuracy for Korean, on the other hand, suggests that too much attention may have been directed towards acoustically salient L2 cues (e.g., F0 range) in the perception of L1 prosody.
English spoken word recognition for Japanese native speakers: A comparison with online and offline processing
Authors: Sakamoto Yoko
Published: November 2016

The aim of this study was to investigate the mechanisms of English (L2) spoken word recognition for Japanese native speakers by two experiments using a cloze test. In Experiment 1, 90 Japanese university students were divided into three groups based on their listening level. Then they took a listening test of a CNN material. The correct rates and error patterns were analyzed. The result showed that the correct rates for three groups were less than 50%, however, the upper group took the highest correct rate and the lowest number of blanks, extra phoneme insertions and phoneme recognition errors. In Experiment 2, 32 Japanese university students were divided into two groups, and one group took a cloze test without listening, and the other took the cloze test with listening. The results of correct number showed that the similar tendency between two groups. This may indicate that listening to L2 is difficult, as much research has suggested, but if Japanese speakers continue to learn English listening, they can better develop recognition of the spoken word more accurately and the inferring skill from top down information such as grammar and semantics may play a role for listening in the second language.
Cross-linguistic perception of clearly spoken English tense and lax vowels based on auditory, visual, and auditory-visual information
Authors: Leung Keith K. , Redmon Charles , Wang Yue , Jongman Allard , Sereno Joan
Published: November 2016

Studies on acoustic and visual characteristics of English tense and lax vowels show consistent enhancement of tensity contrasts in clear speech. However, the degree to which listeners utilize these enhancements in speech perception remains unclear. The present study addresses this issue by testing speech style effects on tense and lax vowel perception by 23 native English and 30 non-native Mandarin-Chinese listeners in audio-only (AO), audio-visual (AV), and visual-only (VO) stimulus modes. English and Chinese listeners showed similar relative differences in performance by mode (VO < AO < AV) and style (plain < clear). However, the two groups differed in the nature of the interaction between tensity, style, and stimulus mode. English listeners showed advantages for clear speech for both tense and lax vowels in all but VO stimuli, whereas Chinese listeners showed a clear speech advantage only for tense vowels, while clear lax vowels showed no improvement in AO and reduced accuracy in AV and VO. While temporal and spectral acoustic cues may coordinate to preserve or improve tense-lax category identity in clear speech, non-native listeners may not be attending to both dimensions. Further, Chinese listeners' greater reliance on visual information may account for their less accurate lax vowel identification.