bluuebunny/crossref_metadata_2025 huggingface dataset:
Seismic landmine detection using microphones as near-ground sensors
Authors: Larson Gregg D. , Martin James S. , Scott Waymond R.
Published: October 2013

Seismic landmine detection systems interrogate the near-surface layers of the ground by propagating Rayleigh surface waves through the region of interest and remotely detecting surface displacements. However, in handheld or robotic applications, commercial microphones could be utilized as near-ground sensors. The primary surface wave for landmine detection is the Rayleigh surface wave, which propagates at subsonic speeds in typical soils. Therefore, the acoustic wave generated in the air by the Rayleigh wave is evanescent. In general, the Rayleigh waves acoustic pressure can only be accurately measured well within a seismic wavelength of the surface. As ambient acoustic noise and reverberation tend to decrease the signal-to-noise ratio, several techniques have been investigated to improve the measurements. The signal-to-noise ratio of microphone measurements is significantly improved by decreasing the microphone’s height above the soil surface or by improving the coupling of the microphone to the evanescent field with a horn. Planar near-field acoustic holography has also been used to back-propagate these signals and calculate surface displacements; this can potentially enhance the performance by preferentially amplifying the effects of the Rayleigh wave. Measurements with microphones have detected both anti-personnel and anti-tank landmines and compare well with radar sensor measurements.
Usage of acoustical filters in transmission line enclosures as a replacement of fiber absorber
Authors: Ilkorur Onur , Yuksek Ismail , Omurlu Emre
Published: October 2013

The need for small-size loudspeaker enclosures is gaining importance, as the dimensions of the modern houses are getting smaller. Transmission line loudspeaker enclosures need more space than most other loudspeaker enclosures because of their design basics. In many commercial transmission line enclosures, fiber material is used for damping of the standing waves inside the line, resulting in a large size enclosure with a loss in sensitivity. However, their low frequency response is regarded as superior to some other enclosure types. In this paper, the frequency response of a transmission line enclosure is examined by replacing the fiber absorber with axial acoustical filters. It has been shown that, axial acoustical filters can perform as fiber absorber, requiring less space and improving the sensitivity. The other advantage of axial acoustical filters over fiber absorber is the simplicity of their electro-acoustic model. Measurements are performed using a Clio Standard System for fiber and axial acoustical filters. Electro-acoustic model and the measurement results are compared. The advantages of using axial acoustical filters are represented.
Acoustics for the musically-gifted at Berklee College of Music
Authors: Hoover Anthony K.
Published: October 2013

Berklee College of Music has offered an undergraduate course in applied acoustics for eighteen years, and a growing number of students have chosen a career in acoustics. This paper will summarize some of the approaches used to convey meaningful information and methods, while also encouraging interest in acoustics, to a creative and energetic student population that traditionally avoids math and science. This paper will review the textbook developed for this class, the Acoustical Society At Berklee, and the annual Berklee Teachers On Teaching.
Developing technologies for bioacoustic vocal profiling as a viable component of integrative medical diagnostics and treatment
Authors: Edwards Sharry K.
Published: October 2013

Over the past 20+ years the pioneering field of Human Bioacoustics, which includes voice spectral analysis, has begun to model the frequencies and architecture of human vocalizations to identify the innate mathematical templates found within the various system of the human body. Using the idea that the voice is a holographic representation of health and wellness, these non-invasive techniques are being advanced to the extent that a computerized Vocal Profile, using a system of Frequency Equivalents, can be used to accurately quantify, organize, interpret, define, and extrapolate biometric information from the human voice. This information, in turn, provides the opportunity to predict, direct, and maintain intrinsic form and function. This novel approach has provided an accumulation of significant data but until recently has been without an efficient biological framework of reference. The emerging Mathematical Model being assembled through Human Bioacoustic research likely has the potential to allow Vocal Profiling to be used to predict and monitor health issues from the very first cries of a newborn through the frequency foundations of disease and aging.
Phase statistics of multiply scattered ultrasonic waves in dynamic mesoscopic systems
Authors: Page John H. , Cowan Michael L. , Van Tiggelen Bart
Published: October 2013

In weakly scattering materials, detecting motion by measuring the change in phase of reflected ultrasonic waves forms the basis of the well-known technique of Doppler ultrasound. In strongly scattering media, these methods break down and the technique of diffusing acoustic wave spectroscopy (DAWS) was developed [Cowan et al., Phys. Rev. Lett. 85, 453 (2000)]. To explore the use of phase information to investigate the dynamics of multiply scattering media, the temporal fluctuations in the phase of ultrasonic waves transmitted through a time-varying mesoscopic sample have been measured. We have compared phase statistics and correlations to detailed theoretical predictions based on circular Gaussian (C1) statistics [Genack et al., Phys. Rev. Lett. 82, 412 (1999)]. So far, excellent agreement is found. The cumulative phase is found to undergo a Brownian type process, described by a phase diffusion coefficient. A fundamental relationship between the variance in the phase of the transmitted waves and the fluctuations in the phase of individual scattering paths is predicted theoretically and verified experimentally. This relationship not only gives deeper insight into the physics of the phase of multiply scattered waves, but also provides a new, mesoscopic way of probing the motion of the scatterers in the sample. a)Currently at Department of Physics, University of Toronto, Toronto, ON, Canada M5S 3E3
Loudness estimation in the presence of vertical vibrations
Authors: Parizet Etienne , Marpe Benjamin
Published: October 2013

The goal of the study was to check whether vibrations submitted to a subject can modify his loudness evaluation. For that purpose, the subject was seated on a rigid chair vertically moved by a shaker, at the frequency of 28 Hz and at 6 different levels. He was also exposed to a pure sound: either a 28 Hz tone produced by a subwoofer, or a 1000 Hz tone produced by headphones. For each combination of sound and vibration levels, the subject had to estimate the magnitude of the loudness of the tone, as compared to a reference tone, heard without any vibration excitation. He also had to evaluate the magnitude of vibration using a 10 point scale. Twenty subjects participated in the experiment. The results showed that vibrations did not influence loudness estimation. On the other hand, the estimation of vibration level was significantly influenced by the level of the 28 Hz pure tone, which can indicate an interaction between the perception of sound by the body and the perception of vibrations.
Reading skills and the discrimination of English vowel contrasts by bilingual Spanish/English-speaking children: Is there a correlation?
Authors: Levey Sandra
Published: October 2013

This study examined the discrimination of English vowel contrasts in real and novel word-pairs by 21 children: 11 bilingual Spanish/English- and 10 monolingual English-speaking children, 8–12 years of age (M=10; 6; Mdn=10; 4). The goal was to determine if children with poor reading skills had difficulty with discrimination, an essential factor in reading abilities. A categorial discrimination task was used in an ABX discrimination paradigm: A (the first word in the sequence) and B (the second word in the sequence) were different stimuli, and X (the third word in the sequence) was identical to either A or to B. Stimuli were produced by one of three different speakers. Seventy-two monosyllabic words were presented: 36 real English and 36 novel words. Vowels were those absent from the inventory of Spanish vowels. Discrimination accuracy for the English-speaking children with good reading skills was significantly greater than for the bilingual-speaking children with good or poor reading skills. Early age of acquisition and greater percentage of time devoted to communication in English played the greatest role in bilingual children’s discrimination and reading skills. The adjacency of vowels in the F1-F2 acoustic space presented the greatest difficulty.
English vowel learning by speakers of Mandarin
Authors: Thomson Ron I.
Published: October 2013

One of the most influential models of second language (L2) speech perception and production [Flege, Speech Perception and Linguistic Experience (York, Baltimore, 1995) pp. 233–277] argues that during initial stages of L2 acquisition, perceptual categories sharing the same or nearly the same acoustic space as first language (L1) categories will be processed as members of that L1 category. Previous research has generally been limited to testing these claims on binary L2 contrasts, rather than larger portions of the perceptual space. This study examines the development of 10 English vowel categories by 20 Mandarin L1 learners of English. Imitation of English vowel stimuli by these learners, at 6 data collection points over the course of one year, were recorded. Using a statistical pattern recognition model, these productions were then assessed against native speaker norms. The degree to which the learners’ perception/production shifted toward the target English vowels and the degree to which they matched L1 categories in ways predicted by theoretical models are discussed. The results of this experiment suggest that previous claims about perceptual assimilation of L2 categories to L1 categories may be too strong.
Vowel space development in a child acquiring English and Spanish from birth
Authors: Andruski Jean , Kim Sahyang , Nathan Geoffrey , Casielles Eugenia , Work Richard
Published: October 2013

To date, research on bilingual first language acquisition has tended to focus on the development of higher levels of language, with relatively few analyses of the acoustic characteristics of bilingual infants’ and childrens’ speech. Since monolingual infants begin to show perceptual divisions of vowel space that resemble adult native speakers divisions by about 6 months of age [Kuhl et al., Science 255, 606–608 (1992)], bilingual childrens’ vowel production may provide evidence of their awareness of language differences relatively early during language development. This paper will examine the development of vowel categories in a child whose mother is a native speaker of Castilian Spanish, and whose father is a native speaker of American English. Each parent speaks to the child only in her/his native language. For this study, recordings made at the ages of 2;5 and 2;10 were analyzed and F1−F2 measurements were made of vowels from the stressed syllables of content words. The development of vowel space is compared across ages within each language, and across languages at each age. In addition, the child’s productions are compared with the mother’s and father’s vocalic productions, which provide the predominant input in Spanish and English respectively.
Training Japanese listeners to identify American English vowels
Authors: Nishi Kanae , Kewley-Port Diane
Published: October 2013

Perception training of phonemes by second language (L2) learners has been studied primarily using consonant contrasts, where the number of contrasting sounds rarely exceeds five. In order to investigate the effects of stimulus sets, this training study used two conditions: 9 American English vowels covering the entire vowel space (9V), and 3 difficult vowels for problem-focused training (3V). Native speakers of Japanese were trained for nine days. To assess changes in performance due to training, a battery of perception and production tests were given pre- and post-training, as well as 3 months following training. The 9V trainees improved vowel perception on all vowels after training, on average by 23%. Their performance at the 3-month test was slightly worse than the posttest, but still better than the pretest. Transfer of training effect to stimuli spoken by new speakers was observed. Strong response bias observed in the pretest disappeared after the training. The preliminary results of the 3V trainees showed substantial improvement only on the trained vowels. The implications of this research for improved training of L2 learners to understand speech will be discussed. [Work supported by NIH-NIDCD DC-006313 & DC-02229.]
Perception of vowels by learners of Spanish and English
Authors: Garcia-Bayonas Mariche
Published: October 2013

This study investigates the perception of English vowels /i I/, /u U/, and /e EI/ and Spanish /i u e/ by native-speakers (NS) and learners (L) and compares these two sets of vowels cross-linguistically. Research on the acquisition of vowels indicates that learners can improve their perception with exposure to the second language [Bohn and Flege (1990)]. Johnson, Flemming, and Wright (1993) investigated the hyperspace effect and how listeners tended to choose extreme vowel qualities in a method of adjustment (MOA) task. The theoretical framework of this study is Fleges (1995) Speech Learning Model. The research question is: Are vowels selected differently by NS and L using synthesized data? Spanish learners (n=54) and English learners (n=17) completed MOA tasks in which they were exposed to 330 synthetically produced vowels to analyze spectral differences in the acquisition of both sound systems, and how the learners vowel system may vary from that of the NS. In the MOA tasks they were asked to select which synthesized vowel sounds resembled the most the ones whose spelling was presented to them. The results include an overview of the vowel formant analysis performed, and which vowels are the most challenging ones to learners.
Questionnaire study of perceived listening quality in renovated university classrooms
Authors: Hodgson Murray , Davies Hugh
Published: October 2013

The research reported here investigated the effect of renovations on student perception of the listening environment in university classrooms. It involved four large classrooms at the University of British Columbia which were studied before and after acoustical renovation. Details of the renovations were identified. Measurements of reverberation time, background-noise level and sound propagation were made in each case. Room-average Speech Transmission Indices were calculated as a physically-based summary quality measure, and their changes on renovation were determined. Questionnaires designed to determine student and instructor perception of the listening environment, as well as the personal, academic and environmental factors that might affect it, were administered to a large number of students taking classes in each classroom, and their instructors, before and after renovation. A summary Perceived Listening Ease (PLE) score, measuring student perception of the quality of the listening environment, was calculated for each questionnaire from the responses. Room-average PLE scores, and the changes on renovation, were then calculated. These results were related to the physical measurement results. Physical, personal, academic and environmental factors affecting the changes in PLE score were investigated. The implications of the results for classroom design were considered.
Investigation of noise issues at U-Hill Elementary School
Authors: York Natalie , Hodgson Murray
Published: October 2013

University Hill Elementary School (U-Hill) has a reputation amongst its teachers, staff and parents as being a noisy school. The present work is an assessment of the acoustical environment at U-Hill with a focus on evaluating how various noise sources contribute to the total noise levels measured in four classrooms. A questionnaire was completed by several of U-Hill’s teachers to determine their reactions to the school’s acoustical environments and what they perceived to be the prevalent noise sources. Standard physical measurements of classroom background noise and reverberation time were made and compared to existing acceptability criteria. Measurements of sound propagation and transmission were made to determine how noise propagates in the hallway, as well as into and between adjacent learning spaces, and the effect of open doors and door grates. Dosimeters were used to monitor sound levels at various hallway source locations and received in the four classrooms studied. Octave-band measurements of typical noise-source levels, such as children walking in the hallways and entering through school doors were made. The measurement data was used to estimate the contributions to total noise levels in the four classrooms of the various noise sources inside and outside the classrooms.
A nearshore observatory for Antarctic krill: Analysis of the spatial variability in their distribution and abundance
Authors: Warren Joseph D. , Demer David A.
Published: October 2013

Annual surveys of the distribution and abundance of Antarctic krill are conducted by the United States Antarctic Marine Living Resources Program in order to assist fishery managers in conserving this economic and ecologic resource. These surveys utilize a large vessel which does not sample close (within 10 km) to the South Shetland Islands. These islands are home to many krill predators (fur seals and penguins) who often forage in these nearshore waters. In order to better understand the abundance and distribution of the krill in these waters and to determine the physical and biological factors affecting the krill, a nearshore observatory has been created that combines multiple sensors and platforms to provide improved spatial and temporal coverage of the nearshore region of Livingston Island. This study utilizes a large research vessel, a small inflatable vessel, an array of instrumented buoys, and a pilot project involving an Autonomous Underwater Vehicle. This presentation will discuss acoustic backscatter measurements made from both large and small vessels. Results from the most recent field season (Jan–Feb 2005) will be presented as well as data from previous years (2002, 2004). [Work supported by the NSF Office of Polar Programs and NOAA.]
Feasibility of noninvasive ultrasound delivery for tumor ablation and targeted drug delivery in the brain
Authors: Hynynen Kullervo , McDannold Nathan , Clement Greg , White Jason , Treat Lisa , Yin Xiangtao , Jolesz Ferenc , Sheikov Nickolai , Vykhodtseva Natalia
Published: October 2013

The objective of our research during the past few years has been to develop multichannel ultrasound phased arrays for noninvasive brain interventions. We have been successful in developing methods for correcting the skull induced beam distortions and thus, are able to produce sharp focusing through human skulls. This method is now being tested for thermal ablation of tumors, with results from animal studies demonstrating feasibility. In addition, the ability of ultrasound to open the blood-brain barrier (BBB) locally has been explored in animal models. The results suggest that the transcranial ultrasound exposures can induce BBB opening such that therapeutic agents can be localized in the brain. This tool is especially powerful since the beam can be guided by MR images, thus providing anatomical or functional targeting. This talk will review our current status in this research, which ultimately aims for the clinical use of this methodology.
Ultrasound enhanced thrombolysis: Clinical evidence
Authors: Alexandrov Andrei V.
Published: October 2013

Phase II CLOTBUST randomized clinical trial (Houston, Barcelona, Edmonton, Calgary) evaluated patients with acute ischemic stroke due to intracranial occlusion and treated with intravenous tissue plasminogen activator (TPA) within 3 h of symptom onset. Randomization: monitoring with pulsed wave 2 MHz transcranial Doppler (TCD) (Target) or placebo monitoring (Control). Safety: symptomatic bleeding to the brain (sICH). Primary end-point: complete recanalization on TCD or dramatic clinical recovery by the total NIHSS score <3, or improvement by >10 NIHSS points within 2 hours after TPA bolus. All projected 126 patients were randomized 1:1 to target (median NIHSS 16) or control (NIHSS 17). sICH: 4.8% Target, 4.8% Controls. Primary end-point was achieved by 31 (49%, Target) versus 19 (30%, Control), p<0.03. At 3 months, 22 (42% Target) and 14 (29% Control) patients achieved favorable outcomes. Continuous TCD monitoring of intracranial occlusion safely augments TPA-induced arterial recanalization, and 2 MHz diagnostic ultrasound has a positive biological activity that aids systemic thrombolytic therapy. For the first time in clinical medicine, the CLOTBUST trial provides the evidence that ultrasound enhances thrombolytic activity of a drug in humans thereby confirming intense multi-disciplinary experimental research conducted worldwide for the past 30 years.
A physical model and experimental testbed for real-time simulation of flute-like instruments
Authors: de la Cuadra Patricio , Fabre Benoît , Abel Jonathan S. , Smith Julius O.
Published: October 2013

In the last decades, a wealth of experimental data has been gathered concerning sound production in flute-like instruments. These data have driven the development and fine tuning of analytical models for the physical processes involved. Here, a number of these results are integrated into a real-time physical model of a flute-like instrument. The model proposed is one-dimensional and driven by a single input pressure. The system was designed in the spirit of a laboratory testbed, where geometric and performance parameters can be controlled in real time, and in which important physical quantities can be viewed in real time, either in the time domain or frequency domain. In this way, the user may observe and validate the behavior of variables that would otherwise be hidden in the feedback loop. Additionally, the system was designed in a modular fashion, so as to allow independent substitution and adjustment of any of the model blocks. So as to allow real-time implementation and parameter control, a novel time-varying jet filter has been developed which not only closely matches measured jet oscillation amplitudes as a function of jet geometry and frequency, but may be rapidly slewed in response to quickly changing performance parameters.
Control of diffusion in digital waveguide reverberators
Authors: Huang Patty
Published: October 2013

Variable diffusion has been incorporated into many room acoustics models, which allows for the representation of materials with different scattering properties. By simulating the scattering of sound waves off surfaces in an acoustical enclosure, a more realistic sound field is produced. Due to constraints on the algorithm architecture and a preference for late reverberation which approaches decaying gaussian noise, it is less common for diffusion to be featured as an adjustable parameter in artificial reverberators. However, parameterized diffusion can be a tool for tailoring the character and density of the reverberant tail, enabling the generation of a greater variety of reverbs. This paper will present methods for implementing and controlling diffusion in artificial reverberation models based on digital waveguides. Sound examples will be given during the presentation.
The effect on sound propagation in streets of the distribution of acoustic scatterers on facades
Authors: Oldham David J. , Ismail Mostafa R.
Published: October 2013

Until recently street noise propagation models assumed that faade reflections were either totally specular or totally diffuse. However, the characteristics of building facades are such that some energy will be reflected specularly and some diffusely. Many current models, therefore, use a scattering coefficient to characterize the diffuse reflection characteristics and the assumption is made that a fraction of the sound energy falling on any point on the facade will be scattered to the same degree. From observation it can be seen that facades are not homogeneous but consist of surfaces which are planar in nature but feature discontinuities such as windows, doors, ledges, etc. which will tend to act as distributed scattering centers. The effect of distributions of scattering centers on the propagation of sound in streets is examined using a combined image source and randomly scattered sound rays. Computer generation of street models using an object based approach enables the study of many different configurations using RAYNOISE software. Results are compared with those obtained assuming a homogeneous distribution of facade scattering using both RAYNOISE and a technique proposed by the authors. The results of a scale model experiment to investigate the effect of distributed scatters are presented.
Microscopic traffic modelling in urban noise assessment
Authors: De Coensel Bert , Botteldooren Dick , De Muer Tom , Peeters Bert , van Blokland Gijsjan
Published: October 2013

The temporal structure of the urban soundscape can be rather complex, due to the presence of many screening and reflecting surfaces and many different sound sources, of which traffic noise is the most dominant. From the point of view of soundscape research, the background level as well as the time structure of noise peaks are important. However, these indicators cannot be estimated easily by current noise prediction models, based on static traffic flows. Therefore, a dynamic traffic noise model was used, based on a microscopic traffic simulation. This way, individual vehicles can be traced, each having an associated set of noise sources that can depend on vehicle properties such as speed and acceleration, as well as on road properties such as the surface type. The model further consists of an ISO 9613 based propagation component, which can account for multiple reflections and diffractions. Maps of statistical noise levels, but also of more complicated measures reflecting the time structure of the soundscape, can be produced. This way, the soundscape contribution of single vehicles can be traced, as well as the influence of more general vehicle properties, such as the contribution of vehicle acceleration noise to the soundscape at junctions.
Auditory spectral integration of dynamic signals
Authors: Feth Lawrence , Krishnamurthy Ashok , Hack Daniel
Published: October 2013

Auditory spectral integration often refers to the ability of the auditory system to sum information across a wide frequency range to improve the detectability of a supra-critical bandwidth signal in a masking experiment. However, in other paradigms, the spectral components of these broad bandwidth signals can be resolved by auditory system. These findings lead to a resolution versus integration paradox for the frequency domain similar to the resolution versus integration paradox in the time domain that led to the multiple-looks hypothesis [N. F. Viemeister and G. H. Wakefield, J. Acoust. Soc. Am., 90, 858–865 (1991)]. In speech, spectral integration refers to finding that two or more resonance peaks in a synthetic vowel can be approximated by a single peak located at the spectral center-of-gravity (COG). In 1996, Lublinskaja demonstrated that changing the COG of a two-resonance signal over time leads listeners to hear a virtual frequency transition that follows the dynamic COG. Dynamic signals may require the auditory system to take multiple looks in both time and frequency. This talk will present a series of psychoacoustic experiments using dynamic signals and a computational model that incorporates peripheral auditory processing and a modification of the PSC model.
L1 literacy affects L2 pronunciation intake and text vocalization
Authors: Walton Martin
Published: October 2013

For both deaf and hearing learners, L1 acquisition calls on auditive, gestural and visual modes in progressive processes over longer stages imposed in strictly anatomical and social order from the earliest pre-lexical phase [Jusczyk (1993), Kuhl & Meltzoff (1996)] to ultimate literacy. By contrast, L2 learning will call on accelerating procedures but with restricted input, arbitrated by L1 literacy as can be traced in the English of French-speaking learners, whether observed in spontaneous speech or in text vocalization modes. An inventory of their predictable omissions, intrusions and substitutions at suprasegmental and syllabic levels, many of which they can actually hear while unable to vocalize in real-time, suggests that a photogenic segmentation of continuous speech into alphabetical units has eclipsed the indispensable earlier phonogenic module, filtering L2 intake and output. This competing mode analysis hypothesizes a critical effect on L2 pronunciation of L1 graphemic procedures acquired usually before puberty, informing data for any Critical Period Hypothesis or amounts of L1 activation influencing L2 accent [Flege (1997, 1998)] or any psychoacoustic French deafness with regard to English stress-timing [Dupoux (1997)]. A metaphonic model [Howell & Dean (1991)] adapted for French learners may remedially distance L1 from L2 vocalization procedures.
Perceived nativeness and sensitivity to temporal adjustments in speech
Authors: Wang Yue , Behne Dawn M.
Published: October 2013

Native Mandarin Chinese speakers productions of English consonant-vowel (CV) syllables have shown syllable-internal temporal adjustments in the direction of native (English)-like CVs (Wang and Behne, 2004). The current study presents two experiments investigating whether these temporal adjustments affect perceived nativeness. For three production types (native-English, Chinese productions of English, native-Chinese), three syllable-internal timing patterns (English-like, Chinese-English-like, Chinese-like) were applied, resulting in nine stimuli types. Native English listeners judged how English-like each stimulus was on a 7-point scale. In the first experiment, production-types and timing patterns were randomized. Results show that listeners can reliably identify nativeness of the three productions, with Chinese productions of English perceived as intermediate to the native Chinese and native American English productions. Listeners also showed a tendency toward using timing within the CV to identify nativeness. In the second experiment the same materials were therefore blocked by production type. Results reveal the perceptual saliency of the temporal adjustments in nonnative productions. These findings support a view of L2 acquisition as a gradual process toward the target L2 (e.g., Caramazza et al., 1973). The current study extends this view, showing evidence that listeners can perceive the inter-language system, bearing the nature of both L1 and L2.
The effect of speaking rate on perception of syllables in second-language speech
Authors: Tajima Keiichi , Akahane-Yamada Reiko
Published: October 2013

Past studies on second-language (L2) speech perception have suggested that L2 learners have difficulty exploiting contextual information when perceiving L2 utterances, and that they exhibit greater difficulty than native listeners when faced with variability in temporal context. The present study investigated the extent to which native Japanese listeners, who are known to have difficulties perceiving English syllables, are influenced by changes in speaking rate when asked to count syllables in spoken English words. The stimuli consisted of a set of English words and nonwords varying in syllable structure spoken at three rates by a native English speaker. The stimuli produced at the three rates were presented to native Japanese listeners in a random order. Results indicated that listeners’ identification accuracy did not vary as a function of speaking rate, although it decreased significantly as the syllable structure of the stimuli became more complex. Moreover, even though speaking rate varied from trial to trial, Japanese listeners’ performance did not decline compared to a condition in which the speaking rate was fixed. Theoretical and practical implications of these findings will be discussed. [Work supported by JSPS and NICT.]
Acoustics of contrastive prosody in children
Authors: Patel Rupal , Piel Jordan , Grigos Maria
Published: October 2013

Empirical data on the acoustics of prosodic control in children is limited, particularly for linguistically contrastive tasks. Twelve children aged 4, 7, and 11 years were asked to produce two utterances ‘‘Show Bob a bot’’ (voiced consonants) and ‘‘Show Pop a pot’’ (voiceless consonants) 10 times each with emphasis placed on the second word (Bob/Pop) and 10 times with emphasis placed on the last word (bot/pot). A total of 40 utterances were analyzed per child. The following acoustic measures were obtained for each word within each utterance: average fundamental frequency (f0), peak f0, average intensity, peak intensity, and duration. Preliminary results suggest that 4 year olds are unable to modulate prosodic cues to signal the linguistic contrast. The 7 year olds, however, not only signaled the appropriate stress location, but did so with the most contrastive differences in f0, intensity, and duration, of all age groups. Prosodic differences between stressed and unstressed words were more pronounced for the utterance with voiced consonants. These findings suggest that the acoustics of linguistic prosody begin to differentiate between age 4 and 7 and may be highly influenced by changes in physiological control and flexibility that may also affect segmental features.
An overview of geophysical investigations at archaeological sites in Helike, Greece
Authors: Witten Alan , Rich Jamie
Published: October 2013

Helike is an area on the south-central coast of the Gulf of Corinth. This name is derived from the lost Classical Greek city of Helike that vanished during an earthquake and subsequent tsunami in 373 BC. It was original believed that the remains of Helike were located offshore in the Gulf of Corinth; however, early searches of this area proved fruitless. More recently, boreholes developed in the coastal plain revealed marine sediments that date to the Classical Greek period suggesting that, as a result of uplift and/or sedimentation, Helike now lies onshore. This find stimulated a sequence of ongoing geophysical investigations and excavations that have revealed buried architecture and artifacts from three periods; Early Bronze Age, Classical Greek, and Roman.
Backscattering of short acoustic pulses from 3-D rough surfaces: Statistical properties of first arrivals
Authors: Godin Oleg A. , Fuks Iosif M. , Charnotskii Mikhail I.
Published: October 2013

Time history of a pulse backscattered by a rough surface contains information about position of the surface and properties of the scatterers. Such information is utilized successfully in a number of remote sensing techniques ranging from echo sounding of the ocean bottom to medical ultrasonics and satellite altimetry. In this paper, statistical properties of backscattered waves are considered in the geometrical acoustics approximation. The probing pulse duration is assumed to be sufficiently short so that signals backscattered in a vicinity of individual specular points on a rough surface do not overlap in time. Theoretical results previously obtained in a 2-D problem [I. M. Fuks and O. A. Godin, Waves Random Media 14, 539–562 (2004)] are extended to sound scattering from 3-D rough surfaces by following an approach developed in stochastic geometry. Predictions of an asymptotic theory are verified against results of a numerical simulation. Travel times and intensities of the first and the second arrivals of the backscattered wave are quantified in terms of statistical moments of roughness. It is found that, as in 2-D case, the travel time and the intensity are strongly correlated; on average, the earlier a signal arrives, the smaller is its intensity.
Benefits of teaching voice amplification as related to subjective laryngeal symptoms and perceived voice quality in teachers
Authors: Jonsdottir Valdis
Published: October 2013

Loud speaking due to noisy working conditions is a common cause for teachers’ voice disorders. One way to diminish the vocal load of teaching is to make use of technical equipment. This Icelandic study explores: (1) if the use of amplification in classrooms would diminish the teachers’ experienced symptoms of vocal fatigue; and (2) whether there is a possible change in perceptual voice quality during a teachers’ working day. Thirty-three teachers, from grade school to university level, voluntarily served as subjects. They used amplifiers while teaching for one week at least. After that, they filled out a questionnaire concerning their symptoms and experiences. The results showed that the majority of teachers found amplification beneficial. They found it easier to talk and experienced less fatigue. The few disadvantages were technical. For a perceptual analysis, three females and two males (mean age 51 years) with long teaching experience and three or more dysphonic symptoms during the term, had their speech recorded while teaching, with and without amplification. In the clinical examination, no pathological changes were found in the vocal folds. In both studies, the quality of the voices was esteemed better when amplification was used.
Installation and impact of sound field systems on hearing and hearing impaired children and their teachers
Authors: Dockrell Julie , Rigby Kate , Shield Bridget , Carey Anne
Published: October 2013

An evaluation of the installation and use of sound field systems in ten schools in England has been carried out. The evaluation included noise surveys of classrooms, questionnaire surveys of pupils and teachers and experimental testing of children with and without the use of SFS. The aim of this project was to investigate the impact of SFS on teaching and learning in elementary school classrooms, in particular, to ascertain whether the SFS differentially benefited children with hearing impairments. Barriers to teachers use of SFS were found in terms of equipment placement and maintenance, appropriate training, and teacher’s knowledge. Nonetheless positive reports are recorded from both teachers and pupils. Teachers’ and pupils’ perceptions are compared with objective data evaluating change in performance when SFS are used for language and cognitive tasks. Data from children with hearing impairments and additional learning needs are analyzed for comparative purposes. The results are discussed in terms of effective practice for the use of SFS with elementary school pupils.
Real world issues in classroom acoustics for hearing impaired students
Authors: Kleinschmidt Klaus
Published: October 2013

Experience is being gained from evaluating and modifying the acoustical properties and background noise levels of existing classrooms for use by hearing impaired students. Projects include more than 25 schools in public school systems that are mainstreaming handicapped children. Various practical and economic restrictions have led to recommendations for modifications that do not necessarily comply with ANSI S12.60 2002. Examples of real world conditions and practical solutions will be described.
Stimulus-response characteristics of a harbor porpoise during active echolocation and passive hearing studied with auditory brain stem recordings (ABR)
Authors: Beedholm Kristian , Miller Lee A.
Published: October 2013

We evaluated the stimulus-response characteristics of hearing by a harbor porpoise using narrow band pulses resembling the animal’s own echolocation pulse (130 kHz, 100 us), but shifted in frequency (80, 100, 125, 160 kHz). Our animal was trained to accept two suction cup electrodes and to station 1 m below the water surface. Stimuli could be presented either as simulated echoes at a fixed delay (5 ms) relative to the animal’s echolocation signals, or at a constant rate chosen by the experimenter. Stimulus levels were varied between 90 and 150 dB re 1uPa and the ABR responses were averaged (16 or more responses) at each level. The relationship between input level (in dB) and ABR amplitude was reasonably linear for simulated echo and constant rate experiments. Regression lines were calculated to determine the level at which the response met the noise, defining the ABR threshold. There was little difference in the ABR threshold (100 to 110 dB re 1uPa) for the four frequencies. The rate of growth of the ABR response with increasing stimulus level was steepest at 125 kHz, which could well reflect a relatively denser population of neurons tuned to this frequency area. [Work done at Fjord & Baelt, Kerteminde, Denmark, and supported by ONR.]
Geoacoustic parameters inversion by ambient noise in South China Sea experiment of ASIAEX
Authors: Wei Ruey-Chang , Kuo Yao-Hsien , Chen Cheng-Hung , Chan Hsiang-Chih
Published: October 2013

Knowing bottom geoacoustic parameters is of great importance for using sonar systems effectively in shallow water. This study is based upon the vertical line array (VLA) in South China Sea experiment of the Asian Seas International Acoustic Experiment (ASIAEX), dated from May 3, 2001 to May 16, 2001, in which the ambient noise was also measured in shallow water. Beamforming is used to calculate the vertical directionality of ambient noise, but limited by the array element spacing, the major analysis frequency range is 100 to 400 Hz. Comparison between forward modeling (normal mode code) and experimental results show the energy ratio of up-looking and down-looking beams, which can be referred to the energy reflection coefficient of the bottom-potentially a function of angle and frequency. From the reflection coefficient, critical parameters of the sediments such as sound speed, density, and attenuation coefficient can be obtained. Finally, this result is verified by on-site chirp sonar surveys during the experiment, and also by other inversion investigation in this area using other sound source.
Uncertainty bounds for geoacoustic inversions due to sound speed variations in water column
Authors: Lin Ying-Tsong , Lynch James F.
Published: October 2013

The uncertainty bounds for geoacoustic inversion results due to sound speed variability in the water column perturbed by internal waves are assessed. Our previous work showed that if the sound speed variations are not taken account into the water column model, they will affect the accuracy of geoacoustic inversions. In this paper, we seek to quantify how well the error bounds could be given under certain knowledge of the sound speed variations. In doing so, the equivalent transform method derived from the linear perturbation theory plays a role in error transferral from water column to bottom. The water column variability is decomposed into ocean dynamic modes or as empirical orthogonal function (EOF) modes. Obtaining the ocean dynamic modes requires having the buoyancy frequency profile, whereas obtaining the EOF modes requires having vertical time series data. In general, it is difficult to assemble full statistics of the sound speed variations, so we examine the uncertainty bounds of the inversion results in the case where only partial statistics can be observed.
Classification of acoustic signals using the statistics of the 1-D wavelet transform coefficients
Authors: Taroudakis Michael I. , Tzagkarakis George
Published: October 2013

The representation of an acoustic signal in terms of the wavelet sub-band coefficients is studied using their statistical features. This type of representation is suggested as an alternative tool for tomographic or geoacoustic inversions. Using a set of representative shallow water environments, the variation of the statistical behavior of the sub-band coefficients is associated with corresponding variations of the environmental parameters. Low frequency signals suitable for ocean acoustic tomography are simulated. It is shown that the statistics of the sub-band coefficients are best described using non-Gaussian heavy-tailed distributions such as those of the alpha-stable family. The variations of the distribution parameters are measured using special statistical similarity functions such as the Kullback-Leibler divergence which has been adopted in the present study. The distances between the statistical parameters of a given and reference signals determined by these functions, can be used for subsequent non-linear inversions aiming at the recovery of the environmental parameters.
Bioheat Transfer Model (BHTE) based temperature estimation technique for high intensity focused ultrasound therapy monitoring
Authors: Kaczkowski Peter J. , Anand Ajay
Published: October 2013

The spatial distribution of tissue temperature is an essential indicator of thermal therapy progress, treatment safety and efficacy. Here, it is shown through in vitro experiments that temperature rise can be accurately measured during therapy delivery and post-treatment cool down phases using RF backscatter data collected with a modified ultrasound scanner. RF data is acquired prior to, during, and after HIFU exposures, in tissue mimicking phantoms and excised animal tissue. Through two calibration experiments, initial estimates for key BHTE parameters (local thermal diffusivity, and magnitude of the HIFU heat source) and the temperature dependence of ultrasonic travel time are obtained prior to therapy. Tissue heterogeneity over a larger targeted region of interest is modeled as a change in the magnitude of the focal heat source. During therapy this magnitude is updated using an iterative optimization technique that minimizes the difference between predicted and measured travel time values. Temperature and thermal dose maps are generated throughout therapy delivery and post-treatment cooling periods. The ultrasound derived estimates are validated against independent thermocouple measurements close to but not at the HIFU focus. This model-based technique permits noninvasive temperature estimation throughout the entire therapeutic range, and is thus a departure from previously reported techniques.
Single crystal cylinder transducers for sonar applications
Authors: Robinson Harold , Stevens Gerald , Buffman Martin , Powers James
Published: October 2013

A segmented cylinder transducer constructed of single crystal lead magnesium niobate-lead titanate (PMN-PT) has been under development at NUWC and EDO Corporation for several years. The purpose of this development was to provide an extremely compact, high power broadband source. By virtue of their extraordinary material properties, ferroelectric single crystals are the ideal transduction material for developing such compact broadband systems. This presentation shall review the evolution of the transducer design as well as present the results of a successful in-water test conducted at NUWC in October of 2003. It shall be shown that design changes intended to eliminate spurious modes limiting the transducer bandwidth first observed in 2002 were successful, resulting in a transducer with a clean frequency response and an effective coupling factor of 0.85. The measured transducer admittance was in nearly exact agreement with theoretical predictions. The NUWC in-water tests demonstrated that the single crystal cylinder achieved an admittance bandwidth (based on the Stansfield criterion) of over 100%, while the tuned power factor was 0.8 or more over 2.5 octaves of frequency. Additionally, the transducer produced 12 dB higher source levels than a similarly sized PZT transducer. [Work sponsored by DARPA.]