bluuebunny/crossref_metadata_2025 huggingface dataset:
From W. House to the present: A brief history of cochlear implants
Authors: Dorman Michael
Published: May 2015

The history of cochlear implants can be divided into four stages. The first, in the early 1960s, was the period of the pioneers (e.g., House, Doyle, and Simmons) who found minimal interest, even distain, from others for their work. The second stage, in the 1970s, saw a worldwide proliferation of groups who designed devices with multiple sites of cochlear stimulation and minimally effective, but very useful, speech coding strategies. The third period (1983–2003) saw the development of more effective processing strategies that utilized multiple sites of stimulation. These strategies, or their derivatives, are the ones in use today. Unfortunately, there have been no gains in group mean word understanding scores for patients fit with a single cochlear implant over a period of about 20 years. For that reason, in the current, fourth stage, researchers have improved performance by adding information (i) from residual low-frequency hearing (under 500 Hz) either in the implanted ear or in the ear contralateral to the implant or (ii) from a second implant. In this talk, I will view these stages from the standpoint of speech acoustics and the seemingly minimal amount of information that is sufficient to support high levels of speech understanding.
The punctuation mark in an equilibrium state: Modern signal processing
Authors: Wilson Blake S.
Published: May 2015

As recently as the late 1980s, the speech reception performance of cochlear implants (CIs) was relatively poor compared to today’s performance. As noted in the 1988 NIH Consensus Statement on CIs, only about 1 in 20 users of the best CIs at the time could carry out a normal conversation without the aid of lipreading. In contrast, the great majority of today’s users can understand speech in relatively quiet conditions with their CIs and restored hearing alone. Indeed, most users communicate routinely via telephone conversations. As noted in the 1995 NIH Consensus Statement on CIs in Adults and Children, “A majority of those individuals with the latest speech processors for their implants will score above 80 percent correct on high context sentences, even without visual cues.” Such abilities are a long trip from total or nearly total deafness. In this talk, I will (1) present some historical aspects; (2) describe the jump up in performance that was achieved in 1989 and provided the basis for many subsequent developments; and (3) mention some possibilities for further improvements in these already marvelous devices.
Neuroplasticity in deafness: Evidence from studies of patients with cochlear implants
Authors: Sharma Anu
Published: May 2015

Deafness alters the normal connectivity needed for an optimally functioning sensory system—resulting in deficits in speech perception and cognitive functioning. Cochlear implants have been a highly successful intervention because they bypass cochlear damage and directly stimulate the auditory nerve and brain, taking advantage of high degree of neuroplasticity of the auditory cortex. Deaf adults and children who receive intervention with cochlear implants have provided a unique platform to examine the trajectories and characteristics of deprivation-induced and experience-dependent neuroplasticity in the central auditory system. I will describe changes in neural resource allocation secondary to hearing impairment, cross-modal cortical re-organization from the visual and somatosensory modalities, and the multimodal and cognitive re-organization that results from auditory deprivation. Overall, it appears that the functional activation of cognitive circuitry resulting from cortical reorganization in deafness is predictive of outcomes after intervention with electrical stimulation. A better understanding of cortical functioning and reorganization in auditory deprivation has important clinical implications for optimal intervention and re-habilitation of cochlear implanted patients. [Work supported by NIH.]
Imaging with reconfigurable active acoustic metamaterials
Authors: Popa Bogdan , Cummer Steven
Published: May 2015

We present a design procedure to obtain active metamaterial structures that cover a large range of linear and non-linear acoustic responses, and whose flexibility makes it suitable to numerous applications. The presentation will briefly outline the types of material properties enabled, and then focus on the potential of this approach to various imaging applications. The design method is illustrated experimentally using a very thin metamaterial slab whose functionality is set electronically. This ensures that multiple imaging techniques can be demonstrated using the same physical slab by simply swapping the electronic modules that determine the metamaterial behavior. Using this method, we implement a thin acoustic lens whose focal length can be controlled at will. In addition, we show how time reversal imaging techniques can be implemented in real-time and in a continuous manner. Finally, the slab is configured to act as an acoustic multiplexer that takes sound incident from multiple directions and funnels it in exactly one direction.
Effect of air volume fraction and void size on the performance of acoustically thin underwater noise isolation panels
Authors: Hicks Ashley J. , Haberman Michael R. , Wilson Preston S.
Published: May 2015

We present experimental measurements of the acoustic behavior of underwater sound absorbing and isolating panels composed of three deeply sub-wavelength layers. The panels were constructed with an inner layer of Delrin plastic containing through-thickness circular air-filled holes sandwiched between two rubber layers. Panel isolation efficacy was quanitifed by measuring insertion loss for non-dimensional panel thicknesses, kd, ranging from 7.2 x 10-3 to 8.5 x 10-2. Finite element numerical simulations will be discussed which indicate that the panel structure mimics a planar encapsulated bubble screen exactly one bubble thick but displays measured performance that is significantly more broadband. Experimental and numerical results indicate that panels with kd ranging from 2.8 x 10-2 to 7.2 x 10-2 can generate a frequency-averaged insertion loss ranging from 5 to 12 dB, dependent on air volume fraction in the panel. The effect of individual air pocket resonance frequency on insertion loss will also be discussed. [Work supported by ONR.]
Experimental analysis of intraglottal flow and geometry
Authors: Oren Liran , Khosla Sid , Gutmark Ephraim
Published: May 2015

During phonation, skewing of the glottal area and glottal flow refers to phenomenon that occurs when the area or the flow decelerates more rapidly than it accelerates. This skewing is clinically important because it increases the glottal efficiency (defined by the acoustic intensity divided by the subglottal pressure). Current theoretical models predict that skewing of the area is not directly proportional to skewing of the flow due to the affects of vocal tract inertance. Recently, we have developed a method that can measure airflow velocity, the distance between the folds, and the glottal flow rate in excised canine larynx. In the current study, PIV measurements are taken in five excised canine larynges having all the structures above the vocal folds removed. The results show strong correlation between the maximum closing rate at the superior aspect of the folds and the lowest negative pressure that is computed inside the glottis during the closing phase. The results also show that the magnitude of the divergence angle that develops in the glottis during closing is directly proportional to the glottal efficiency. These are important observations because they hold new mechanisms that can increase glottal efficiency without the affects of vocal tract inertance.
Indirect evidence of perturbation leads to changes in production of voice amplitude and fundamental frequency
Authors: Casserly Elizabeth D. , Talesnick Lily , Celestin Nicholas
Published: May 2015

In this study, we explore the juncture of real-time feedback-based changes in speech production and those initiated by top-down knowledge of external factors such as audience characteristics or audience listening conditions. Twenty-four speakers were asked to solve interactive puzzles via remote auditory connection with an experimenter under five signal transmission conditions: normal/baseline, increased signal amplitude, decreased amplitude, + 100 cents shift in pitch, and −100 cents shift in pitch. Evidence of these changes was available to talkers only through the speech of the experimenter; no sidetone was introduced in the connection and listening conditions for talkers were otherwise normal. In response to hearing amplitude shifts in their partner’s speech, 19/24 talkers significantly altered their mean voice amplitude, while 6/24 altered f0 in response to shifted experimenter vocal pitch (RM-ANOVA, all corrected p’s < 0.05). Approximately 30% of responses countered the signal manipulation (e.g., f0 increase in response to low experimenter f0), while the remainder imitated the observed change. This combination of perturbation-like compensation and imitation/accommodation suggests that speakers can interpret transmission circumstances differently, or pursue different speech-related goals, during even very simple, constrained tasks.
Acoustic correlates of creaky voice in English
Authors: Khan Sameer ud Dowla , Becker Kara , Zimman Lal
Published: May 2015

We compared auditory impressions of creaky voice in English to acoustic measures identified as correlates of contrastive voice qualities in other languages (e.g., Khmer, Chong, Zapotec, Gujarati, Hmong, Trique, and Yi). Sixteen trained linguistics undergraduates listened to the IP-final word “bows” produced five times each by five American English speakers reading the Rainbow Passage, and gave a rating from 0 (no creak) to 5 (very creaky). Results show that stronger auditory impressions of creak are significantly correlated with lower f0, lower cepstral peak prominence (CPP), lower harmonics-to-noise ratios (HNR), and higher subharmonics-to-harmonics ratio (SHR). This suggests that listeners perceive greater creakiness as the voice becomes lower pitched, less periodic, and more audibly interspersed with subharmonic frequencies (i.e., diplophonia). Notably, none of the spectral amplitude measures proposed as acoustic correlates of glottal configurations for creaky voice in other languages (e.g., lower H1-H2 for smaller open quotient, lower H1-A1 for smaller posterior aperture, lower H1-A3 for more abrupt closure, etc.) was significantly correlated with these judgments in any expected direction. Taken together, these results suggest that while listeners consistently use pitch and periodicity as cues to creak, speakers might be varying in their articulatory strategies to achieve those acoustic effects.
Coarticulation and speech stability for three lifespan groups
Authors: Belmont Alissa , Frisch Stefan A. , Maxfield Nathan
Published: May 2015

Using ultrasound recording of tongue movement during speech production, repetitions of kV initial monosyllabic words were measured for nine vowel contexts in three different age groups (children 8–12, young adults 18–35, and older adults 50–65). Coarticulation was measured by average minimum point-to-point distance between tongue traces (Zharkova & Hewlett 2009). Speech stability was quantified by average distance between productions with the same vowel. Coarticulation was quantified by average distance between productions with different vowels. For all three talker groups (n = 11 or greater per group), the measure of coarticulation was greater than the measure of stability, demonstrating coarticulatory differences. Across the lifespan, measures of coarticulation and stability both decreased from group to group. This suggests that speech production becomes more segmental (less coarticulated) and more stable (less variable) continuously throughout the lifespan of speaking experience.
Coupling relations underlying complex coordinative patterns in speech production
Authors: Lancia Leonardo , Grawunder Sven , Rosenbaum Benjamin
Published: May 2015

In studying linguistic behavior, we are often faced to complex dynamical patterns arising from the highly coordinated activity of many partially autonomous processes. In this work, we apply a new approach aimed at studying abstract coupling relations coordinating the behavior of dynamical systems governed by goal oriented behavior. The approach, based on an original version of recurrence analysis, allows to deal with the principal difficulties of this task, which are mainly related to the heterogeneity, the lack of separability and the lack of stationarity of the processes under study. The method is validated trough simulations of theoretical systems and it is adopted to capture (1) invariant abstract coupling structure underlying systematically varying trajectories of the speech articulators involved in the production of labial and coronal plosive and fricative consonants (produced at slow and fast speech rate by five German speakers and recorded via electromagnetic articulography); (2) systematic differences in the coordination between energy modulations observed at different frequency bands in the acoustic signal and showing the interplay between syllable and stress related processes and its relation to rhythmic differences between typologically different languages (pear story narrations were recorded from five speakers per language in German, Italian, French, English, and Polish).
The effect of palate morphology on lingual shape during vowel production
Authors: Vick Jennell , Foye Michelle L. , Schreiber Nolan , Lee Gregory S.
Published: May 2015

A previous report described significant differences between males and females in the shape of the tongue during the production of vowels (Vick et al., 2014). The purpose of the present study was to understand the influence of palate morphology on these measured differences in tongue shape. This study examined tongue movements in consonant-vowel-consonant sequences drawn from words in phrases as produced by 32 participants, including 12 adults (6m, 6f) and 20 children (2m and 2f at each age of 11, 12, 13, 14, and 15 years). Movements of four points on the tongue were tracked at 100 Hz using the Wave Electromagnetic Speech Research System (NDI, Waterloo, ON, CA). Palate curvature measures were derived from a hard palate trace made with a 6dof probe sensor. The phrases produced included the vowels /i/, /I/, /æ/, and /u/ in words (i.e., “see,” sit,” cat,” and “zoo”). The horizontal curvature of the tongue was calculated at the trajectory speed minimum associated with the vowel production using a least-squares quadratic fit of the positional coordinates of the four points on the tongue. A regression model was used to determine the variance in tongue shape explained by palate morphology in the 32 talkers.
An articulatory model of the velum developed from cineradiographic data
Authors: Laprie Yves
Published: May 2015

The objective of this work is to develop an articulatory model which comprises the velum so as to be able to synthesize nasal vowels and consonants in French. Unlike one exception of a velum model developed from static 3D MRI images there is no model derived from articulatory data that can be used within a vocal tract articulatory model. Our model is derived from X-ray films of the DOCVACIM database. The velum contour has been tracked semi-automatically and then carefully checked and corrected from 1050 mid-sagittal images of the vocal tract. Principal component analysis has been applied onto these contours. The first component represents more than 50% of the variance and controls the velum opening. The next two components capture 20 and 12 % of the variance, respectively, and explain the deformation of the velum between open and close configurations. In parallel a series of MRI images of nasal vowels and consonant of French was analyzed. The velum opening roughly has a shape of a bean, whose length is almost constant for one speaker and width is given by the 2D articulatory model. Together with an evaluation of the nasal cavities this model can be used for articulatory synthesis.
An acoustic phonetic study on the production accuracy of lexical stress contrasts in Arabic and Mandarin-accented English
Authors: Keyworth Paul R.
Published: May 2015

The researcher explored the socio-morphophonetic characteristics of English as a second language lexical prosodic competence. One hundred participants from Midwest USA (29), Saudi Arabia (38), and China (33) were recorded producing English lexical stress (ELS) in tokens containing seven different stress-moving suffixes—[-ic], [-ical], [-ity], [-ian], [-ify], [-ial], and [-ious]. Fundamental frequency, duration, and intensity productions were analyzed using Praat. In total, 2125 vowels in 800 spectrograms were analyzed (excluding stress placement and pronunciation errors). Statistical sampling techniques were used to evaluate acquisition of accurate ELS production versus native language and language proficiency. Speech samples of native-speakers were analyzed to provide norm values for cross-reference and to provide insights into the proposed Salience Hierarchy of the Acoustic Correlates of Stress (SHACS). The results support the notion that a SHACS does exist in the L1 sound system and that native-like command is attainable for English language learners through increased study/L2 input. Saudi English speakers, who often do not fully reduce vowels, produced durational contrasts more accurately when they had studied English for longer. Similarly, proficient Chinese learners of English seemed to be able to overcome negative transfer from their tonal system as they produced pitch in a more native-like manner.
Speech rhythm processing
Authors: Perdereau Xiao
Published: May 2015

Speech rhythm is one of the main prosodic features of spoken languages. The quantitative research data on this topic in the literature are not numerous may be due to the confusing divergence in this concept definition. In order to render clear this concept, we investigated a speech segment in Mandarin. Due to its delicate temporal structure, it leads easily to the semantic ambiguities, well known in speech recognition. In order to understand how human manage the speech meaning in a natural language processing, we designed a series of lexical duration and pause interval modulations based on the speech segment for production. By analyzing the resultant acoustic patterns, we observed two types of temporal grouping. The type 1 is context dependent, the time range has no regularity, the modulations suffered from semantic ambiguities. The type 2 includes the stable patterns presenting temporal regularities. We consider the temporal structures in this type as speech rhythm. This definition corresponds to the articulatory periodicity that produces the consonant and vowel alternations. They are context independent and reproducible.
Harvey C. Hayes: First superintendent of the Sound Division at the Naval Research Laboratory, Washington, D.C
Authors: Erskine Fred T.
Published: May 2015

Harvey Cornelius Hayes, physicist, had a long tenure (1923–1947) as the first Superintendent of the Sound Division (later renamed Acoustics Division) at the Naval Research Laboratory (NRL), Washington, D.C. In the period prior to World War II, Hayes led a small group of only five to eight researchers that was devoted to developing active (echo-ranging) sonar and improved passive (listening) sonar for the navy’s surface ships and submarines. They developed a tunable type of sonar that found widespread use in World War II. They conducted field experiments to take detailed measurements on the propagation of sound in oceanic acoustic ducts. They developed techniques for silencing “singing” propellers in navy ships and aircraft carriers by sharpening propeller edges. During World War II the Sound Division expanded in size about twentyfold and NRL researchers conducted numerous experiments to address navy concerns regarding sonar performance. Sound Division researchers made significant advances including the development of communications equipment for divers, torpedo countermeasures, the development of streamlined sonar domes for ships, control and stabilization of sonar transducers, methods for localization of a submerged target beyond the resolution of the sonar beam, and coordination of sonar systems with fire-control systems. In the period following World War II, Hayes initiated new efforts on shock and vibration, crystal development, and physiological acoustics.
The Submarine Signal Company
Authors: Howarth Thomas R.
Published: May 2015

The Submarine Signal Company (SSC) was established in 1901 in Boston, MA, and was the first commercial enterprise organized to conduct underwater sound research and to develop equipment to be used for increasing safety of navigation. The initial product line (prior to 1914) included underwater bells for shore based stations, buoys, and lightships, as well as encased microphones for sound detection on the ships. The bells were used for navigational and hazard warning purposes. In April 1912, future SSC President H. J. W. Fay had a chance meeting with Professor Reginald Fessenden at a Boston railroad station. This meeting led to an invitation for a Fessenden visit to SSC where upon Reginald so impressed company managers and engineers that SSC hired Fessenden consulting services to redesign their hydrophones. Based on this and later contributions to underwater sound products, H. J. W. Fay and R. A. Fessenden are two of the five named pioneers of the ASA award known as “The Pioneers of Underwater Acoustics Medal”. This presentation will discuss the formation and product lines of SSC through their formation till 1946 when they were merged with Raytheon Company.
The naval science of Albert Beaumont Wood, O.B.E., D.Sc
Authors: Buckingham Michael J.
Published: May 2015

A. B. Wood’s career in Naval scientific research spanned a period of nearly 50 years, from the early days of the first World War to the time of his death in 1964. After graduating from Manchester University with a first class honors degree in Physics he seemed destined for a career of distinction in academia. But, like many young men at the time, when the U.K. was becoming deeply embroiled in war, he felt dissatisfied with the cloistered academic life and instead became one of the first two physicists to receive an official appointment with the Admiralty under the newly formed “Board of Invention and Research”. Thus, the Royal Navy Scientific Service was born and Dr. Wood began his celebrated research into the propagation of sound underwater, about which little was known at the time. Many of his technical achievements were made at the Admiralty Research Laboratory, Teddington and, shortly before his death, he spent a year at the U.S. Naval Electronics Laboratory, as it was then called, in San Diego. He was awarded the Pioneer of Underwater Acoustics medal by the Acoustical Society of America and his Text Book of Sound is still a standard work on the subject.
R. J. Urick—Introduction of the sonar equations
Authors: Bradley David
Published: May 2015

The Sonar Equations were developed during the Second World War to calculate the maximum ranges of sonar equipment. They were formally discussed in a series of reports published by the Office of Naval Research in the mid 1950’s entitled “A Summary of Acoustic Data” authored by R. J. Urick and A. W. Pryce. Later codified in Urick’s Book, Principles of Underwater Sound, they are the primary tool for design, development, and testing of undersea acoustic hardware. They also provide a useful means for estimating expected values of marine physical properties (e.g., ambient noise, transmission loss) or, conversely, a sanity check on data collected at sea. The presentation is focused on the history of the sonar equations, their early use and transition to modern form and employment.
The cardiovascular effects of noise on man
Authors: Babisch Wolfgang
Published: May 2015

Noise is pervasive in everyday life and induces both auditory and non-auditory health effects. Systematic research of the effects of noise on the cardiovascular system has been carried out for more than 50 decades. Noise is a stressor that affects the autonomic nervous system and the endocrine system. Animal experiments, laboratory and field studies carried out on humans provide evidence that persistent exposure to environmental noise affects physiological endpoints, which in turn are adversely associated with cardiovascular diseases. These include hypertension, coronary heart disease, and stroke. New endpoints have been studied, including clinical states of metabolic syndrome such as diabetes mellitus. Chronic sleep disturbance is considered as an important mediator of the effects. Public health policies rely on quantitative risk assessment to set environmental quality standards and to regulate the noise exposure that is generated by environmental noise sources in the communities. Meta-analyses were carried out to derive exposure-response relationships between noise and cardiovascular health. Most of the epidemiological studies refer to road traffic and aircraft noise. No biologically determined threshold values can be determined. Cardiovascular effects due to noise and traffic-related air pollutants are largely independent of one another due to different biological mechanisms.
Transdisciplinary, clinical analysis of the effects of noisy environment on the cognitive performance of healthcare providers
Authors: Xiang Ning , Sykes David , Triner Wayne R. , Dodds Peter
Published: May 2015

Karl Kryter’s pioneering and encyclopedic effort begun over six decades ago to document “The Effects of Noise on Man” opened a door to trans-disciplinary, translational research. His approach continues to challenge many of us in acoustical science, medicine, and the development of codes and standards. The authors have emulated Kryter’s trans-disciplinary approach by forming a unique and stable partnership between doctors at a major medical center, scientist-engineers at a polytechnic institute, and a division of the American Hospital Association that promulgates evidence-based building criteria. This partnership enables detailed and insightful, quantitative research to be conducted in a variety of previously inaccessible clinical environments (e.g., hospitals) on the impacts of ambient noise on the cognitive performance of healthcare professionals. The authors couple psychoacoustic methods and soundscape analysis with cognitive performance tests to examine questions of major concern in the healthcare professions such as the extent to which medical errors are caused by environmental stresses such as noise. Several studies are currently being designed that highlight the challenges and opportunities of emulating Kryter’s approach using 21st century methods.
Karl Kryter—Soundscape pioneer
Authors: Brooks Bennett M.
Published: May 2015

Karl Kryter was a pioneer in the soundscape analysis field, even before the field had a name. Defined as the combination of the study of physical sound parameters with the perception of sound by listeners in an environmental context, soundscape analyses were conducted and reported by Kryter well before the term “Soundscape” was coined by R. Murray Schafer in 1977. These included several studies of community reactions to noise from subsonic aircraft while Kryter was with Bolt, Beranek and Newman in the 1950’s. Those studies were followed by laboratory and field tests of listener reactions to aircraft noise in the 1960’s. Kryter compiled and compared similar attitudinal and perceptional studies of transportation noise by other researchers in his 1970 book “The Effects of Noise on Man”. This compilation has proven to be comprehensive and enduring in its presentation of noise perception data. Kryter’s insights from those early studies provide valuable guidance to current and future soundscape researchers and soundscape design practitioners.
Contribution of floor treatment characteristics to background noise levels in health care facilities, Part 2
Authors: Ackerman Adam C. , Zonenshine Jonathan , King Eoin A. , Celmer Robert D. , LoVerde John J.
Published: May 2015

Additional acoustical tests were conducted as Part 2 of a previous study [JASA 136(4), 2219–(2014)] on ten types of commercial grade flooring to assess their potential contribution to surface-generated noise within healthcare facilities. These floor samples utilized an ECORE ForestFX sheet vinyl wear layer and tested with rubber-backing thicknesses ranging from 2 mm–10 mm, plus a composite backing composed of two 2 mm layers. Two types of ECORE International adhesives, EGripIII and Evolve, were tested as part of the adhesive used during manufacturing as well as with local mounting of all floors on concrete substrates. Sound power tests were conducted in compliance with ISO-3741-2010 for two source types, an impact tapping machine and a rolling hospital cart. The sample that achieved the lowest radiated sound power levels for both the rolling cart and tap tests was Forest FX sheet vinyl with 10 mm rubber backing and Evolve adhesive. Two trends were observed. First, measured sound power levels reduced as backing thickness rose. Second, the Evolve adhesive demonstrated lower sound power levels for all tap/rolling tests when compared with those utilizing the EGripIII adhesive. The suitability of using thicker floor backings in healthcare facilities are discussed. [Work supported by Paul S. Veneklasen Research Foundation.]
Karl Kryter: The evolution of the Articulation Index
Authors: Allen Jont B.
Published: May 2015

When one trained in speech perception hears the name Karl Kryter, they immediately think of the AI standard, which Kryter ferried through the standards process. Today, the AI has been studied to the point that we are beginning to understand both its beauty, and its fundamental limitations. The AI was created by Fletcher and Galt, as reported first in JASA in 1950, and in Fletcher's two books. It is based on two important intertwined observations: (1) that the average consonant error Pe is exponential in an average of critical band signal to noise ratios (i.e., $Pe(SNR) = 0.015{AI}$) and (2) the total error is the product of independent critical band errors. While AI theory has been verified many times over, the real question is “Why does it work?” In this talk, I will answer this question, and in the process expose the AIs key weaknesses. AI theory has guided us to our modern understanding of speech perception in normal and hearing impaired ears. The publications supporting this work date from 1994–2014 and may be found at http://hear.ai.uiuc.edu/Publications.
Geoacoustic modeling for acoustic propagation in mud ocean-bottom sediments
Authors: Siegmann William L. , Pierce Allan D.
Published: May 2015

This paper reviews research developed since 2007 at BU and RPI, with leadership by the late W.M. Carey, on acoustic properties of mud. Marine mud consists primarily of small clay mineral platelets, which are comprised of crystalline layers and usually carry charge because of isomorphous substitution. Because of resulting electrical forces, the physical nature of mud is considerably different from sand sediments. In particular, as platelets settle under gravity, electrical forces repel face-to-face contact while strong van der Waals forces permit edge-to-face attachment. This platelet aggregation results in card-house structures, for which a tentative quantitative model has been analyzed (J.O. Fayton, RPI Ph.D. thesis). The model preserves basic physics of platelet interactions and leads to low shear wave speed predictions that are consistent with observations. However, because compressional sound speed is independent of the electrostatic interactions, accurate sound speed estimates are available from the Mallock-Wood formula, which also incorporates bubble effects. The basic physical concepts and semi-empirical formulas derived for shear attenuation and its frequency dependence in sandy sediments do not apply for mud, nor do assumptions behind the often cited Biot theory for poro-elastic media. Consideration is given to incorporating geoacoustic models into equations for acoustic propagation in mud.
In situ measurements of sediment compressional and shear wave properties in Currituck Sound
Authors: Ballard Megan S. , Lee Kevin M. , McNeese Andrew R. , Wilson Preston S. , Muir Thomas G. , Costley R D.
Published: May 2015

This paper reports in situ measurements of compressional and shear wave speed and attenuation collected below the sediment-water interface in Currituck Sound, North Carolina. Three measurement locations having distinctly different sediment types will be presented: (1) a near shore site with coarse sand, (2) a shallow-water site with silty fine-grained sand, and (3) an offshore site with loamy clay. At each site, grab samples were collected and later analyzed in the laboratory to quantify physical properties of the sediment, including grain size, density, and porosity. The in situ acoustic data were acquired using two measurement systems, each consisting of four probes mounted on a rigid frame. The shear wave system consisted of bimorph elements to generate and receive horizontally polarized shear waves; the compressional wave system was composed of cylindrically shaped piezoelectric elements. Both systems were manually inserted into the sediment, and waveforms were recorded by shipboard equipment. The measured wave speeds and attentions are compared to predicted values from one or more sediment models using the measured physical properties as inputs. The Biot-Stoll model, grain-shearing theory, Mallock-Wood equation, and card-house theory are considered for this analysis. [Work supported by ERDC, ARL:UT, and ONR.]
Fine-grained sediments from the poroelastic perspective
Authors: Chotiros Nicholas P. , Isakson Marcia J.
Published: May 2015

Fine-grained sediments, such silt and clay, are porous media, consisting of solid particles saturated by water; however, the skeletal structure of the solid component is significantly different than that of larger grained sediments such as coarse and fine sands. The modeling of fine grained sediments from the poroelastic perspective, such as the Biot theory, can be challenging. A stumbling block is the frequency dependence of attenuation, which from experimental measurement is shown to be proportional to the first power of frequency, while the Biot theory generally predicts a second power of frequency dependence at low frequencies. One approach to reconcile this difference is based on the distribution of pore sizes [Yamamoto and Turgut, 1988]. When a broad distribution of pore sizes in taken into consideration, the frequency dependence approaches the first power of frequency within a limited frequency band. Another approach is to examine the relaxation process at the grain-grain contact, which is governed by a thin fluid film in the contact region. In fine-grained sediments, the contact region is extremely small and nano-fluid effects must be expected. In this study, a derivation of a poroelastic model, based on the relaxation process associated with the grain contact region will be discussed. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]
Seabed attenuation inversion from broadband reverberation measurements in the Yellow Sea
Authors: Wan Lin , Badiey Mohsen
Published: May 2015

The Yellow Sea 1996 experiment was the first joint China-U.S. shallow water experiment conducted in August, 1996. The water depth is 75 m with a deviation of ±1 m at the experimental area. The seabed sound speed and attenuation in this experiment have been successfully estimated using the sound propagation measurements [Wan, Zhou, and Rogers, J. Acoust. Soc. Am. 128(2), 2010]. During this experiment, the monostatic reverberation data produced by 1-kg TNT shots provide a spatial sampling of the acoustic field and contains the information of seabed acoustic properties. Thus, the present paper uses the inverted seabed sound speed from the aforementioned propagation measurements as a constraint condition and analyzes the reverberation data for seabed attenuation inversion. The broadband normal mode filter is applied to the reverberation data received by a 32-element vertical line array. The reverberation level of the first three modes is obtained as a function of range to extract the modal attenuation coefficients. The seabed attenuation is inferred by minimizing the difference between the theoretical and measured modal attenuation coefficients. The inverted seabed attenuation over a frequency range of 400–1000 Hz shows non-linear frequency dependence.
Efficient geoacoustic inversion of spherical-wave reflection coefficients for muddy seabeds
Authors: Quijano Jorge E. , Dosso Stan E. , Dettmer Jan , Holland Charles W.
Published: May 2015

This paper presents efficient geoacoustic inversion of high-resolution reflectivity data for a seabed site consisting of a thick mud layer (~10 m) over multi-layered sandy sediments. Wide-angle, broadband reflection-coefficient data were collected using a towed source and a recording hydrophone located a few meters above the seabed. Trans-dimensional Bayesian inversion is applied to estimate sound-speed, density, and attenuation profiles for an unknown number of sediment layers. Due to the experiment geometry, the data should be modeled as spherical-wave reflection coefficients, which require numerical integration of rapidly oscillating functions and can be computationally intensive. Here, a speed-up of two to three orders of magnitude is achieved by introducing a fast Levin-type numerical integration implemented on a graphics processing unit. The new fast integration algorithm/implementation alleviates time constraints for the spherical-wave inversion, which would otherwise require weeks of computation time, and precludes the use of fast but less-accurate plane-wave theory. Inversion results are presented for simulated data and for experimental data collected on the western Malta Plateau. The analysis of muddy sediments in this work is expected to provide insight into the geoacoustics of the New England mud patch, location of the upcoming ONR Seabed Characterization Experiment 2016 (SCAE16).
Measurement of shear wave velocity in marine sediments
Authors: Bradshaw Aaron S. , Baxter Christopher D.
Published: May 2015

This presentation describes the shear wave velocity measurement techniques that have been utilized over that past decade at the Marine Geomechanics Laboratory (MGL) at the University of Rhode Island (URI). The shear wave velocity of marine sediments is of interest to both the underwater acoustics and marine geotechnical engineering communities. In underwater acoustics, sediment shear wave velocity plays an important role in understanding compressional wave attenuation. Geotechnical engineers utilize shear wave velocity, for example, for the analysis of seismic site response and evaluation of soil liquefaction potential. The shear wave measurement techniques that will be covered include laboratory bender element tests made within the triaxial apparatus that allows for the application of situ stress states on the test specimen. Bender elements have also been used in the lab to make shear wave velocity measurements in reconstituted sand fills at very low stress levels, as well as on intact clay sediments directly within a piston core. More recently, field measurements of shear wave velocity have been made using a system developed by colleagues at URI that involves the measurement and inversion of Scholte waves. The presentation aims to stimulate dialog between the fields of underwater acoustics and marine geomechanics on the topic of shear wave velocity.
A novel ultrasound device for estimating bone mineral density at the 1/3 radius
Authors: Kaufman Jonathan J. , Stein Emily , Luo Gangming , Shane Elizabeth , Siffert Robert S.
Published: May 2015

This study evaluated a new ultrasound device for estimating bone mineral density (BMD) at the 1/3 radius (1/3R), as well as investigated its ability to discriminate fracture (fx) and non-fx cases. The device measures two net time delay parameters, NTDDW and NTDCW. NTDDW is the difference between transit time of an ultrasound pulse through soft-tissue, cortex and medullary cavity, and transit time through soft tissue of equal distance. NTDCW is the difference between transit time of an ultrasound pulse through soft-tissue and cortex only, and transit time through soft tissue of equal distance. The square root of the product of these two parameters is a measure of BMD at the 1/3R as measured by DXA. A clinical IRB-approved study measured 77 adults using ultrasound and DXA. An age and sex-matched subset of these subjects was used to determine the capability of DXA and ultrasound to discriminate between fx and non-fx cases. A linear regression showed that BMDUS = 0.19 * {NTDDW * NTDCW}½ + 0.28 and that the linear correlation between BMDUS and BMDDXA was 0.93 (P<0.001). We found that ultrasound measurements yield results that are closely associated with those from DXA. In the case-control fx study, we found a small decrease in mean BMDDXA (1/3R) for the fx cases (P = 0.20) but a somewhat greater decrease in mean BMDUS (P = 0.05). In conclusion, the new ultrasound device should enable significant expansion of the identification of bone loss as occurs in osteoporosis and also may ultimately be able to provide additional data on fx risk.
Piezoelectric response of bone in the MHz range
Authors: Matsukawa Mami , Matsukawa Sayaka , Tsuneda Hiroko
Published: May 2015

The healing mechanism of bone fractures by low intensity ultrasound is not yet to be fully understood. As one possible initial process of this mechanism, we focus on the piezoelectricity of bone and demonstrate that bone can generate electrical potentials by ultrasound irradiation in the MHz range. We have fabricated ultrasonic bone transducers using bovine cortical bone as the piezoelectric device. Electrical potentials induced by the ultrasound irradiation were obtained from all transducers. The electrical potentials changed as a function of time during immersed ultrasonic measurements and became stable when the bone was fully wet. The sensitivities of bone transducers were around 1/1000 of a poly(vinylidene fluoride) ultrasonic transducer and did not depend on the magnitude and alignment of hydroxyapatite crystallites in bone. In addition, the magnitude of the induced electrical potentials changed owing to the microstructure in the cortical bone. The potentials of transducers with haversian structure bone were higher than those of plexiform structure bone, which informs about the effects of bone microstructure on the piezoelectricity.
Sample thickness dependence of Bayesian and modified least squares Prony’s analysis methods on systematically shortened bovine cancellous bone
Authors: Groopman Amber , Wear Keith , Nagatani Yoshiki , Mizuno Katsunori , Matsukawa Mami , Taki Hirofumi , Katz Jonathan , Holland Mark , Miller James
Published: May 2015

The goal of this study was to compare the results from two proposed methods for separating fast and slow waves from mixed-mode signals, one using Bayesian probability theory and one using modified least-squares Prony’s (MLSP) [Wear, J. Acoust. Soc. Am. 133, 2490–2501 (2013)], on measurements of cancellous bone. Ultrasonic through-transmission data were acquired on a bovine femoral head specimen for thicknesses ranging from 15 mm to 6 mm. The thickness was reduced in 1 mm increments and measurements were acquired at each sample thickness [Nagatani et al., Ultrasonics 48, 607–612 (2008)]. A Bayesian parameter estimation analysis was performed on the experimentally acquired signals to isolate the fast and slow waves and to obtain estimates of the fast and slow wave’s ultrasonic properties. Results for the corresponding ultrasonic properties were estimated using the modified least squares Prony’s method plus curve fitting (MLSP + CF) on the same bovine sample by Wear et al. (J. Acoust. Soc. Am. 136, 2015–2024). The results show good agreement between the phase velocities estimated by Bayesian and MLSP + CF analysis methods for both the slow wave and the fast wave. Both analysis methods yielded fast and slow wave phase velocities that depended on sample thickness. This may imply that the propagation model, which is used in both methods, may be incomplete.
Transcranial time-of-flight estimation using backscattered infrared data
Authors: Wang Qi , Howell Mark , Reganti Namratha , Clement Gregory T.
Published: May 2015

Recently, we reported on our observation that diffuse infrared (IR) light transmitted through human skull bone exhibits an intensity that correlates positively with acoustic (1 MHz) time-of-flight data acquired at equivalent locations [POMA 22, 020002 (2015)]. Presently, we investigate the potential to exploit this correlation as a means of correcting for skull-induced aberration. For measurement, a dual ultrasonic/infrared array capable of illuminating a localized region of the skull bone and recording the backscattered light was constructed. The array design utilized 940 nm IR emitters (TSAL4400, 3-mm-diameter) and a single detector (TEFD4300-3 mm) configured to transmit and record under the face of an ultrasonic PZT ring transducer. Initial tests consisted of a three-emitter configuration, with fiberglass-reinforced foil used to isolate the direct infrared signal between the emitters and the receiver. Effects of skin were considered by attaching a skin-mimicking layer to the skull and comparing results with and without the layer. Data acquired on a set of eight skull samples will be presented. Preliminary results show good correlation between ultrasound and IR intensity. [Work supported by NIH award R01EB014296.]Posters will be on display and contributors will be at their posters during the session break from 2:40 p.m. to 3:05 p.m.
Acoustic engineering by design—Example of a service learning course for undergraduate engineering students
Authors: King Eoin A. , Faraci Philip P. , Celmer Robert D.
Published: May 2015

The University of Hartford has two ABET-accredited undergraduate engineering programs in the area of acoustics—a Bachelor of Science in Mechanical Engineering with acoustics concentration and a Bachelor of Science in Engineering with a major in acoustical engineering and music. Students participating in both of these programs take an acoustic engineering design course with a focus on service learning during their sophomore year. Service learning is an alternative to the traditional teaching model and offers students the opportunity to apply their classroom studies to local issues in the community; thus, students achieve academic objectives by meeting real community needs. Each year members of the community approach the University to request assistance with rooms exhibiting poor acoustic characteristics due to improper reverberation times and/or excessive background noise levels. Students are required to design and communicate solutions to these issues in a manner similar to a professional consultation. Recent examples include a science center exhibit hall, a restaurant, an architecture studio classroom, and a retirement community auditorium. This presentation will provide examples of such projects completed as part of this class. Challenges and benefits associated with this service learning course for acoustic engineering undergraduate students will be discussed.