bluuebunny/crossref_metadata_2025 huggingface dataset:
A semi-empirical predictive model for the attenuation properties of fine-grained sediments
Authors: Knobles David P. , Stotts Steven A. , Koch Robert A.
Published: May 2015

It is of interest to be able to predict the acoustic properties (especially the compressional sound speed and attenuation) of sediments that can be classified as mud. An inverse problem is constructed to infer estimates of the surface sediment attenuation, the attenuation gradient, and the frequency exponent and applied to acoustic data in the 10–400 Hz band collected in the Gulf of Oman basin. The results indicate that, unlike a sandy seabed, the surface attenuation is about 0.005 dB/m-kHz and the frequency exponent is close to unity. These estimates are compared to those of an inversion analyses for a shallow-water site in the Gulf of Mexico, which is an environment with similar sediment properties. Further, the inferred attenuation values from both experiments are compared to calculated values from the Buckingham grain-shearing model. The geological histories of the shallow- and deep-water seabeds are compared with the intent of constructing a semi-empirical predictive model for the attenuation properties of fine-grained sediments.
A review of basic to clinical studies of quantitative ultrasound of cortical bone
Authors: Laugier Pascal , Bernard Simon , Vallet Quentin , Minonzio Jean-Gabriel , Grimal Quentin
Published: May 2015

The use of quantitative ultrasound (QUS) for bone has increased sharply over the last two decades. QUS offers potential benefits over other diagnostic modalities which include (1) ex vivo non-destructive testing, (2) in vivo non-ionizing testing, and (3) the ability to assess important cortical bone quality factors which cannot easily be captured with X-ray techniques. These advantages have stimulated widespread interest in basic through clinical studies. For instance, resonant ultrasonic spectroscopy (RUS) has provided gains in ex vivo assessment of the anisotropic stiffness and viscoelasticity of bone despite strong damping. RUS is prone to provide answers to questions that remain open regarding the determinants of cortical bone elastic properties. In vivo QUS technologies using guided waves (GW) have the potential to reveal cortical bone strength-related factors such as the cortical thickness and porosity. These properties can be estimated by comparing the measured dispersion curves with an appropriate waveguide model of the cortical bone. This presentation reviews the ex vivo (RUS) and clinical (GW) studies of cortical bone based on major experimental studies particularly within the past decade. These gains still constitute a prelude to what is to come, given the incessant developments of better instrumentation and signal processing techniques.
Relationships among ultrasonic and mechanical properties of cancellous bone
Authors: Wear Keith A. , Sadoughi Saghi , Nagaraja Srinidhi , Dreher Maureen , Keaveny Tony M.
Published: May 2015

Most clinical bone sonometers measure broadband ultrasound attenuation (BUA) and speed of sound (SOS) in calcaneus. In addition, backscatter coefficient (BC) has been shown to have clinical utility. The objective of this work was to assess the extent to which ultrasonic measurements convey mechanical properties of cancellous bone. Twenty-five defatted human calcaneus samples were investigated in vitro. Normalized BUA (nBUA), SOS, and BC were measured using 500 kHz focused ultrasound transducers. Finite Element Analysis, based on micro-computed tomography images (Scanco microCT 100), was used to estimate stiffness and apparent modulus of the samples. Correlation coefficients from linear regressions were as follows: nBUA vs. stiffness—0.80 (p < 0.0001), nBUA vs. apparent modulus—0.81 (p < 0.0001), SOS vs. stiffness—0.80 (p < 0.0001), SOS vs. apparent modulus—0.84 (p < 0.0001), BC vs. stiffness—0.75 (p < 0.0001), and BC vs. apparent modulus—0.69 (p < 0.001). In conclusion, ultrasonic measurements are very sensitive to mechanical properties of cancellous bone. The mention of commercial products, their sources, or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products by the Department of Health and Human Services.
Ultrasound backscattering from cancellous bone in vivo
Authors: Ta Dean , Tang Tao , Liu Chengcheng , Wang Weiqi
Published: May 2015

Osteoporosis is a musculoskeletal disease characterized by a loss of bone mass and a deterioration of trabecular bone microarchitecture. In recent years, significant progress has been made in the quantitative ultrasound technique, and it has become well established as a noninvasive tool for the assessment of bone status. This report will show the ultrasonic backscatter theory in cancellous bone, analyze the ultrasonic backscattering signals, and to investigate correlations among backscatter parameters and bone mineral density (BMD) in vivo. Ultrasonic backscattering measurements were performed on 1226 subjects (601 males and 625 females) at the right calcaneus in vivo using the novel ultrasonic backscatter bone system. Then, the subjects underwent DXA for the BMD at sites located on the lumbar spine (sBMD) and left hip (hBMD). Spectral centroid shift (SCS), mean trabecular bone spacing (Tb.Sp), backscatter coefficient (BC), and apparent integral backscatter coefficient (AIB) were calculated at the central frequencies of 3.5 and 5.0 MHz. Linear regression showed that the SCS at 3.5 MHz exhibited negative correlations with the sBMD (R=−0.66) and hBMD (R=−0.64). The SCS at 5.0 MHz was also found to be closely related to the sBMD (R=−0.68) and hBMD (R=−0.66). Tb.Sp at 3.5 MHz and 5.0 MHz exhibited negative correlations with the sBMD (R=−0.74) and hBMD (R=−0.66).The correlations between backscatter parameters and BMD were found to be statistically significant in both the male and female groups.
Numerical investigation of fast and slow longitudinal waves backscattered from various depths inside cancellous bone
Authors: Hosokawa Atsushi
Published: May 2015

Ultrasound backscattering in cancellous bone was numerically investigated using three-dimensional (3D) finite-difference time-domain (FDTD) simulations with microcomputed tomographic (μCT) models of the bone. The cancellous bone models with various thicknesses, in which artificial absorbing layers were set at the surfaces opposite to the ultrasound-transmitted surfaces, were prepared. The backscattered waveform inside cancellous bone was isolated by deriving the difference between two simulated waveforms obtained using the bone models with different thicknesses, and the backscatter properties from various depths of the bone were investigated. When an ultrasound pulse wave was transmitted in the direction parallel to the main orientation of the trabecular network, the backscattered waves from the deep bone depths could clearly separate into two waves, which could correspond to the backscattered waves of the fast and slow longitudinal waves propagating mainly in the trabecular elements and the pore spaces. For each of the fast and slow waves, the backscatter coefficient, which was the ratio of the backscattered fast/slow wave amplitude to the incident fast/slow wave amplitude, was obtained. The results showed that both backscatter coefficients were weakly correlated with the bone depth.
Energy flux streamlines versus acoustic rays for modeling an acoustic lens: Testing and refinement
Authors: Dean Cleon E. , Braselton James P.
Published: May 2015

As an extension of recently published experimental work [Cleon E. Dean and Kendez Parker, “A ray model of sound focusing with a balloon lens: An experiment for high school students,” J. Acoust. Soc. Am. 131, 2459–2462 (2012)], preliminary results comparing energy flux streamlines [David M. F. Chapman, “Using streamlines to visualize acoustic energy flow across boundaries,” J. Acoust. Soc. Am. 124, 48–56 (2008)] versus acoustic rays for visualizing the energy flow inside and in the focal region of an acoustic lens in the form of a carbon dioxide filled balloon in air were presented. The sound field was expanded in the usual Legendre polynomials and spherical Bessel functions, and the energy flux vectors at points throughout the regions of interest were calculated [J. Adin Mann III, et al., “Instantaneous and time-averaged energy transfer in acoustic fields,” J. Acoust. Soc. Am. 82, 17–30 (1987)]. Deficiencies in the streamline plotting routines used in this earlier version of Mathematica and subtle differences between acoustic rays and acoustic energy flux streamlines lent itself to an inaccurate perception of the results. This talk uses Mathematica 10 routines to revisit these results and concentrates on testing and verification of the conclusions from the previous work.
Development of boundary element method to analyze acoustic models with comparison to finite element model
Authors: Farahikia Mahdi , Miles Ronald N.
Published: May 2015

Numerical and computational models provide valuable information about engineering designs. Of their desirable benefits is reduction of expenses and feasibility of observing the change in behavior of a model with varying design parameters. In this paper, a boundary element method that was developed in Matlab is described. The approach in developing this method is based on the Green’s function for an unbounded acoustical domain. This model allows reading of computer aided designs to further analyze them in acoustic domain. The results obtained from this method are compared with equivalent finite element models carried out in ANSYS and exact analytical solutions to check for accuracy. Steps in analyzing acoustic models in ANSYS and Matlab are also explained in this paper.
Acoustic requirements for audiometric testing and hearing protector fit-testing with mobile platforms
Authors: Murphy William J.
Published: May 2015

Mobile technology platforms present new challenges for implementing hearing loss prevention programs. Laptop computers, smartphones, and tablets have capabilities to generate 16-bit and sometimes 24-bit audio stimuli for hearing tests. For testing hearing at threshold, the noise floor of the sound card of the computer can pose a limitation. During the development of sound compression standards (e.g., MPEG, AAC, MP3), 24-bit resolution and 96 kHz sampling is necessary to encompass the requirements for dynamic level the frequency range of human hearing. However, hearing screening and fit-testing can be accomplished with 44 kHz sampling rates. However, the bit resolution deserves careful treatment to ensure that output is accurate. This paper will describe features for mobile applications for audiometric testing and hearing protector fit-testing. Several external DAC platforms on Windows 7 based laptops along with a small sample of iOS and Android devices have been tested and demonstrate differing levels of performance. Linearity of the systems and output levels for a standard audiometric headphone will be presented.
Acoustic measurements and modeling of air-filled underwater resonator cavities
Authors: Tseng Laura M. , Lee Kevin M. , Wilson Preston S.
Published: May 2015

This project investigated the near-resonance acoustical properties of submerged air-filled resonator cavities intended for use in underwater noise abatement systems, exploring a potential alternative to encapsulated bubbles. The underwater resonator cavities are air-filled containers resembling Helmholtz resonators, inverted and submerged in water, creating a direct interface between the volume of air trapped inside the cavity and the surrounding water. Experiments were performed with a prototype resonator cavity in a closed water-filled laboratory tank operated in the long wavelength limit (under 500 Hz) and the resonance frequencies and Q-factors were measured for various air-fill volumes. A finite-element simulation was used to examine the behavior of the resonator cavities within the experimental tank apparatus, yielding good agreement with measurements. Finally, free-field models were also developed (a finite-element numerical model and a Helmholtz-resonator-based analytical model), both of which yielded good agreement with the tank measurements. The measurements and models presented here indicate that inexpensive and convenient sub-wavelength laboratory tank measurements, along with simple analytical models can be used to accurately design and verify the free-field behavior of low frequency underwater noise abatement resonators.
Absorption and dispersion in Venus' lower and middle atmosphere
Authors: Raut Mathbar S. , Petculescu Andi
Published: May 2015

Vertical profiles for the sound speed and attenuation coefficient are calculated in the troposphere and mesosphere of Venus. The predictions are based on ambient quantities (pressure, temperature, density, and composition) obtained by measurements and global circulation models. The three major species considered for composition are carbon dioxide, nitrogen, and sulfur dioxide. The thermophysical parameters—specific heats, viscosity, and thermal conductivity—for the principal constituents were obtained by interpolation from the NIST Chemistry Webbook, at the pressure/temperature values of each altitude. A real-gas equation of state was used to account for the dense environment of the Venusian troposphere.
Accurate fast field formulation for a uniformly moving source traveling above an impedance plane
Authors: Tong Bao N. , Li Kai Ming
Published: May 2015

The Lorentz transform, which can be applied to a uniformly moving source, effectively converts the time-domain wave equation to an equivalent problem in frequency-domain due to a stationary source. Standard fast field program (FFP) implementations apply the property of conjugate symmetry in the wavenumber domain for improved efficiency. Recent literature [D. Dragna et al., AIAA 52, 1928–1939 (2014)] suggests the use of a Dopplerized frequency-dependent impedance model to account for the effects of source motion. Consequently, the FFP kernel function is no longer identical for the positive and negative wavenumbers. Additional complications are introduced by the necessity to compute the positive and negative horizontal separation distances in the Lorentz frame to obtain a complete time history of sound pressures for the source approaching and receding from the receiver. Further development of the FFP algorithm in the Lorentz frame is explored such that a frequency-dependent impedance model is developed. Both moving line and point monopole sources are considered in the current investigation. Results are validated against direct numerical integration schemes and with the published time-domain solutions. Applications for an aircraft operating in cruise condition is also examined in the present study. [Work Sponsored by the Federal Aviation Administration.]
Longitudinal results in the childhood development after cochlear implantation study
Authors: Niparko John K.
Published: May 2015

This NIDCD-funded study has aimed to develop a longitudinal, multivariate model of spoken language outcomes after early cochlear implantation. Our national cohort accrued subjects in their infant and toddler stages. As the study enters its 12th year, the study offers a model of post-implant language development, now at a stage when participants are able to self-assess their interaction with peers, school performance, and quality of life. Here, we will present our primary outcome of interest-spoken language acquisition-discussing modifying variables related to auditory function, cognition, device, and environmental variables.
Importance of cochlear health for cochlear-implant function
Authors: Pfingst Bryan E. , Zhou Ning , Colesa Deborah J. , Watts Melissa M. , Strahl Stefan B. , Garadat Soha N. , Schvartz-Leyzac Kara C. , Raphael Yehoash , Zwolan Teresa A.
Published: May 2015

In humans with cochlear implants, functional measures show considerable variation from one stimulation site to another along the electrode array. Our research has demonstrated that (1) the across-site patterns of the functional data are stable over time but differ across subjects; and (2) the across-site patterns are measure specific. These observations are consistent with the hypotheses that implant performance at a given stimulation site is dependent on specific conditions near the site, and that the various functional measures do not all depend on the same conditions. However, we lack direct evidence as to the specific conditions leading to the site-specific differences in performance in humans. Studies in our guinea pig laboratory and elsewhere have demonstrated highly significant correlations between psychophysical or electrophysiological measures of implant function and anatomical measures of cochlear health. Furthermore, the correlated anatomical features differ across functional measures. Finally, some functional measures that are correlated with anatomical measures of cochlear health in animals are predictive of speech recognition ability in human implant users. The data support efforts to preserve and/or restore the health of the implanted cochlea. [This work was supported by NIH/NIDCD grants R01 DC010786, R01 DC010412, and P30 DC05188, and a contract from MED-EL.]
Engineering contributions to the development of the cochlear implant
Authors: Zeng Fan-Gang
Published: May 2015

The cochlear implant is a product of deliberate systems engineering, starting with a clear design goal by physicians to restore human hearing by means of electrical stimulation. The engineering development of the cochlear implant has been a dynamic interplay between a perfectionist's approach attempting to replicate the intricate sensing and processing in a normal biological system and a reductionist's approach building an artificial system with minimal components and complexity. The reductionist's approach won the initial battle as the first FDA-approved single-channel cochlear implant consisted of simply a microphone, an amplifier, and a pair of coils. Borrowing techniques and knowhow’s from diverse engineering areas in acoustics, aerospace, and electronics, modern multi-channel cochlear implants have shifted towards the perfectionist's approach. Acoustic researchers, particularly speech scientists, have played an important role in the engineering development of the cochlear implant. From an engineering perspective, I will highlight development milestones, evaluate their contributions to actual implant performance, and delineate the complicated relationships between artificial and natural hearing.
A transformation-based formulation of an airfoil cloak using Joukowski mapping
Authors: Telly Saliou , Balachandran Balakumar
Published: May 2015

Since its introduction in 2006, the transformation approach to cloaking has been extensively explored for electromagnetic and acoustic fields, due to its intuitive nature as well as the methodology. In this approach, the construction of invisibility cloaks consists of exploiting a change of coordinates to create a void region within a finite space while keeping the outer boundary of the considered space unchanged. Such changes in physical coordinates can be interpreted as a transformation of material properties related to electromagnetics and acoustics, given the invariance of the respective field equations to coordinate change. Based on the transformation, properties of an invisibility cloak can be inferred using available formulae. To this date, this approach has been successfully applied to various two-dimensional geometries including circular and square cylinders. In this work, as an extension, the authors present initial results obtained for the cloaking of a two-dimensional airfoil section. They take advantage of the mapping properties of the well-known Joukowski transformation, a complex mapping that is used in aerodynamics applications.
Acoustoelectric admittance of two-dimensional ferroelectric metamaterial under dispersion curve branching
Authors: Nusierat Ola H. , Cremaldi Lucien , Ostrovskii Igor
Published: May 2015

The acoustoelectric admittance Y of the ZX-cut periodically poled LiNbO3 plate is investigated experimentally and theoretically computed. The sample consists of 88 inversely poled domains of 0.45 mm-long each. The vector voltmeter, digital oscilloscope, and function generator were used to measure the frequency dependencies Y(F) at room temperature. Double peaks were observed in the admittance measurements near the lower edge of a stop-band at frequencies 3.268 MHz and 3.287 MHz. Another double peak exists near upper edge of the acoustic stop band at frequencies 3.651 MHz and 3.663 MHz. The double peak in Y can be explained as follows. Ultrasound in this ferroelectric acoustic metamaterial (FAM) has a so-called stop band when an acoustic wavelength is close to a double-length of ferroelectric domain within the inversely poled structure. The dispersion curves computed by the finite element method reveal an effect of decoupling of two acoustic displacements in a zero-antisymmetric mode. The two displacements Ax and Az along the X and Z axes become decoupled near the boundaries of the acoustic Brillouin zone. This can be explained by different diffraction losses in two orthogonal displacements within the FAM. Computations are in a good agreement with experiments.
Acoustic Poisson-like effect
Authors: Titovich Alexey , Norris Andrew N.
Published: May 2015

A sonic crystal with a particular local resonance is capable of transferring incident acoustic energy to a perpendicular direction. This is done with a square array of cylindrical scatterers vibrating with a non-axisymmetric mode which couples to the anti-symmetric mode (deaf mode) of the crystal via an evanescent band unlocking it from the bandgap boundaries and resulting in perpendicular propagation. The scatterer is an elastic shell designed to be acoustically transparent with impedance and index matched to water, which is vibrating with the n = 2 in-plane bending mode. The shells’ collective motion resembles the quasi-static Poisson effect in elastic solids and results in a quadrupole scattering pattern which causes a purely perpendicular mode to be excited at normal incidence. Thus, the acoustic Poisson-like effect is non-refractive and also highly efficient. Variations of this novel effect will also be discussed such as different local resonances, lattices and crystals. [Support from ONR is gratefully acknowledged.]
Acoustic ground cloaks revisited
Authors: Kerrian Peter , Hanford Amanda , Capone Dean , Miller Scott
Published: May 2015

The unique material properties now obtainable with acoustic metamaterials have led to unprecedented control of acoustic wave propagation, resulting in many applications including acoustic cloaking. The two fundamental approaches in the development of a ground cloak are quasiconformal mapping [Li et al. Phys. Rev. Lett. 101, 203901 (2008)] and coordinate transformations [Popa et al. Phys. Rev. B. 83, 224304 (2011)]. The differences in the required material properties prescribed by these two approaches lie in the amount of anisotropy and inhomogeneity, as well as the size of the cloak relative to object. The coordinate transformation approach has been used to produce a realizable anisotropic homogeneous ground cloak in the acoustic domain. This presentation will highlight the findings of work that examined how advances in metamaterial development could lead to the realization of required material properties for ground cloaks, and explore alternative transformations to expand the applications for acoustic ground cloaks.
Channel and noise robustness of articulatory features in a deep neural net based speech recognition system
Authors: Mitra Vikramjit , Sivaraman Ganesh , Nam Hosung , Espy-Wilson Carol Y. , Saltzman Elliot
Published: May 2015

Articulatory features (AFs) are known to provide an invariant representation of speech, which is expected to be robust against channel and noise degradations. This work presents a deep neural network (DNN)—hidden Markov model (HMM) based acoustic model where articulatory features are used in addition to mel-frequency cepstral coefficients (MFCC) for the Aurora-4 speech recognition task. AFs were generated using a DNN trained layer-by-layer using synthetic speech data. Comparison between baseline mel-filterbank energy (MFB) features, MFCCs and fusion of articulatory feature with MFCCs show that articulatory features helped to increase the noise and channel robustness of the DNN-HMM acoustic model, indicating that articulatory representation does provide an invariant representation of speech.
A method for estimating lingual cavity volume in click consonants
Authors: Miller Amanda L.
Published: May 2015

A method for estimating lingual cavity volume in click consonants is presented. The upper edge of the lingual cavity is estimated from stone palate casts, which were scanned using a Polhemus 3D Digitizer. The floor of the midline of the lingual cavity was estimated using 114 fps mid-sagittal ultrasound traces of the tongue collected with the CHAUSA method (Miller and Finch 2011). The width of the cavity from front to back was estimated by measurements of the cavity width at six different locations in linguograms. Changes in lingual cavity volume for the four coronal click types in Mangetti Dune !Xung are estimated by changing the mid-sagitttal ultrasound trace that corresponds to one of five stages in click production. 3-D images of the changes in cavity volume for each of the four coronal click types recognized by the IPA (2006) are presented.
Measurement of child speech complexity using acoustic landmark detection
Authors: Speights Marisha , Boyce Suzanne , MacAuslan Joel , Fell Harriet
Published: May 2015

An important measure of intelligibility in children is the ability to articulate complex syllables. At the same time, the transcription and analysis of young children’s speech data is laborious and time-intensive, requiring specialized training and expert perceptual abilities on the part of researchers. Researchers have called for automatized methods to quantify these measures of articulatory complexity. One such method, Automatic Syllabic Cluster Analysis, may allow for more efficient analysis by using acoustic landmarks [Stevens et al.,1992] to systematically detect abrupt and maximal events in the speech signal, group them into syllable patterns and further group the syllable patterns into utterances. Statistics derived from these groupings are used to determine the complexity of utterances. Automatic Syllabic Cluster Analysis does not require transcription for analysis of the speech because it is not lexically driven, instead employing measurements of acoustic parameters that characterize changes in articulatory precision. To identify a potential application for this automated approach, this pilot research examines syllabic complexity in children to differentiate between children who are typically developing and those with diagnosed speech disorders. Preliminary results indicate that Automatic Syllabic Cluster Analysis can identify articulatory differences between the groups.
Audio dilation in real time speech communication
Authors: Novak John S. , Archer Jason , Shafiro Valeriy , Kenyon Robert V.
Published: May 2015

Algorithmically decreasing speech tempo, or “audio dilation,” can improve speech perception in attentionally demanding tasks [Gygi & Shafiro (2014), Hear. Res. 310, pp. 76–86]. On-line audio dilation [Novak, et al. (2013), Interspeech 1869–1871] is a recently developed technique that decreases the tempo of audio signals as they are generated. This pilot study investigated effects of on-line audio dilation on performance in interactive problem solving tasks. We used a Diapix task [Baker & Hazan (2011), Behav. Res. Methods 43(3), 761–770] to elicit and record spontaneous speech from pairs of participants under various dilation conditions: participants, seated in different rooms, were asked to find ten differences on two similar pictures, while their speech was either transmitted as spoken or dilated. Conditions tested include stretching one, both, or neither audio signal by 40%. Subsequent analysis shows that the technique, even using this substantial increase, did not interfere with interactive problem solving tasks, and did not lead to changes in speech production rate, measured as number of syllables per second. The lack of negative effects of on-line speech dilation provides a preliminary basis for further assessment of this method in speech perception tasks with high attentional and memory load.
Human-system turn taking analysis for the let’s go bus information system
Authors: Zhao Tiancheng , Eskenazi Maxine
Published: May 2015

We examined turn-taking in the Let’s Go Bus spoken dialog data from two aspects: study the consequences of system barge-in when users are not finished speaking (false system barge-in, FSB); determine whether using a partial recognition result other than the final one produces better results. The consequence of FSBs is a less user-friendly system coupled with poor recognition caused by barge-ins, which divide one user turn into several fragments (UFs). We observed that UFs result in longer dialogs because the dialog manager has to recover from misrecognized utterances. Dialogs with UFs have 34 turns on average those without have 27. Poor recognition and long dialogs together cause lower task success rate. Dialogs with UFs have a success rate of 62% versus 84% for dialogs without. Moreover, we annotated the number of correct and incorrect slots for all partial recognitions. For 51% of the utterances, there exists a partial that contains more correct slots than the final recognition result. This will lead us to develop an algorithm to find the best partial. We conclude that systems that avoid FSB will have more efficient dialogs. They will also have better recognition by using the best partial instead of only the final one.
Shannon entropy predicts the sonority status of natural classes in English
Authors: Llanos Fernando , Alexander Joshua M. , Stilp Christian E.
Published: May 2015

Speech sounds tend to co-occur in the speech stream according to specific combinatory patterns predicted from their sonority status [Parker, S. G. (2002). Quantifying the sonority hierarchy. Unpublished doctoral dissertation, University of Massachusetts, Amherst, MA]. This study introduces a measure of spectral complexity, inspired by Shannon entropy, that ranks American English phonemes into a minimal version of the sonority hierarchy: vowels > approximants > nasals > fricatives > affricates > stops. Spectral complexity for every consonant and vowel in the TIMIT database was calculated by first parsing the phonemes into 20-ms segments and computing an FFT. For each short-term FFT, Shannon entropy was computed using the distribution of relative amplitudes (dB) across frequency. Average entropy across the FFTs was used to index spectral complexity for the phonemes, which were then sorted by sonority status. Results of a between-group comparison with spectral complexity as the independent variable and natural class as the dependent variable revealed the existence of six significantly different groups with spectral complexity ranking according to the sonority hierarchy. These findings suggest that Shannon entropy is a reliable acoustic correlate of sonority and may account for the combinatory patterns of co-occurrence of speech sounds in the speech stream.
A spectral filtering method for tracking formants in children's speech
Authors: Story Brad H. , Bunton Kate
Published: May 2015

Children's speech is typically characterized by high fundamental frequencies (e.g., 300–600 Hz) that create widely spaced harmonic components, producing an apparent undersampling of the vocal tract transfer function. The purpose of this study is to describe a formant measurement technique based on cepstral analysis that does not require modification of the cepstrum itself or transformation back to the spectral domain. Instead, the spectrum is low-pass filtered with a cutoff point (i.e., cutoff “quefrency” in the terminology of cepstral analysis) to preserve only the spectral envelope. To test the method, speech representative of a 2 to 3 year-old child was simulated with an airway modulation model of speech production. The model includes physiologically-scaled vocal folds, vocal tract, and trachea and generates sound output analogous to a microphone signal. The true formant frequencies can be calculated independently of the output signal and thus provide test cases that allow for assessing the accuracy of the formant tracking algorithm. Formant analysis will also be applied to children’s natural speech samples to demonstrate the method. [Work supported by NIH R01-DC011275 and NSF BCS-1145011.]
Double entendre: Embedding a secondary message in pointillistic speech
Authors: Kidd Gerald , Mason Christine R.
Published: May 2015

A dual-purpose application for pointillistic speech (Kidd et al., JASA 126, EL186–201) will be described. The speech was represented by a time-frequency matrix of pure-tone “points” derived from the original stimulus. The pattern of frequencies and intensities of the points coded the primary message while the phases of the points coded an independent secondary message. For example, the audible and intelligible word “shoes” may also convey the (inaudible, unintelligible) ASCII characters of the phrase “The road goes ever on and on…” by the binary phase-coded bit pattern of the pointillistic representation of “shoes.” The success in recovering the secondary message via signal processing was examined while the intelligibility of the primary message in speech recognition experiments was measured. Tradeoffs for accuracy in primary and secondary message transfer/reception were explored for both pointillistic speech and hybrid speech comprising natural and pointillistic representations. Some initial observations about the possible uses and limitations of this approach will be considered. [Supported by AFOSR award FA9550-12-1-0171.]
The Sound Lab at Fort Trumbull, New London, Connecticut, 1945–1996
Authors: Clark Cathy Ann
Published: May 2015

The Navy Underwater Sound Laboratory was formed in 1945 when the U.S. Navy merged on-going efforts of Columbia and Harvard Universities to combat the German U-boat threat in the North Atlantic. Prior to that time, the Division of War Research of Columbia, housed in a single building at Fort Trumbull, was sponsored by the National Defense Research Committee (NDRC) while the Harvard Underwater Sound Laboratory was doing similar work in Cambridge, Massachusetts. For the next 50 years, until it was formally closed in 1996, the “Sound Lab” continued to support virtually all aspects of Naval Warfare technology. This talk will attempt to describe the rich scientific culture and technological contributions of the New London Sound Lab.
Contributions to underwater acoustics by the Naval Ordnance Laboratory (NOL)
Authors: Blatstein Ira , Tino John
Published: May 2015

This presentation documents the contributions to underwater acoustics by NOL, built in White Oak, MD, in 1946 and operated until closing (as the White Oak Laboratory of NSWC) in 1997. Initial work on mine systems led to R&D on a variety of more sophisticated passive/active acoustic weapon systems for mine warfare, submarines, and ASW aircraft. The increasingly complex mission requirements led to research in a wide range of underwater acoustic disciplines and included development of some key measurement systems, platforms, and facilities across a broad range of frequencies. The measurements obtained by NOL personnel advanced the state of knowledge in underwater acoustic short and long range propagation, surface and bottom acoustic reverberation, sound speed variability with depth, as well as a variety of other research topics. This research led to the development of sensors, materials, target detection systems, and other systems that were applied to a wide variety of acoustic systems. The evolution of this work, and its wide variety of applications, will be discussed.
A few Canadian contributions to underwater acoustics
Authors: Merklinger Harold M. , Osler John C.
Published: May 2015

An historical perspective on four Canadian achievements in underwater acoustics will be presented: Towed Variable Depth Sonar (TVDS); Chapman-Harris model for reverberation; seabed-interaction in shallow water, and uninhabited underwater vehicles (UUVs) for Arctic acoustics. The poor performance of hull-mounted sonars in Canadian waters during WWII prompted TVDS development in 1947. The resulting prototype (CAST/1X) was tested against UK and US developmental systems in 1958. Subsequently, the UK purchased the Canadian system and the US “re-packaged” their sonars according to the Canadian design. An understanding of the effects of back-scattering from the sea surface and bottom was required to model sonar system performance. Experiments began circa 1960 leading to a new model for sea surface back-scattering, and revealing the ocean volume as an additional factor. The conditions governing propagation and noise in shallow waters remained mysterious in the 1970s, until the significant role of the seabed emerged through theoretical developments (e.g., loss due to shear-waves) and experiments conducted over a variety of seabed types. Political, sovereignty and energy issues prompted Canada to investigate under-ice acoustics in the Arctic beginning circa 1957. The efforts ultimately resulted in the ability to undertake under-ice acoustic and geophysical surveys using long endurance UUVs.
History of underwater electroacoustic transducer standards, calibration methods, facilities, and some early contributors
Authors: Brown David A. , Paolero Anthony
Published: May 2015

The practice of realizing underwater acoustic standards and methods for the systematic calibration of the wide variety of electroacoustic transducers is rich in tradition and has given rise to some unique facilities. In about 1940, the US Navy Office of Scientific Research and Development established a center for Underwater Acoustic Metrology under the expertise of Columbia University in collaboration with Bell Laboratories, which subsequently resulted in the establishment of the Underwater Sound Research Laboratory (USRL) in Orlando Florida with unique acoustic lake testing facilities. That facility later became a detachment of the Naval Research Laboratory (USRD) and was the home for a concerted effort in transducer development and calibration for many years. The National Bureau of Standards and later the National Institute for Standards (NIST) deferred the activity of establishing and maintaining underwater acoustic standards and calibration methods to the USRD Navy facility. This paper summarizes some of the transducers standards, methods and facilities and many of the important contributions of early pioneers in this field including Ira Groves, Robert Bobber, Joseph Blue, and others. USRD continues today as a division at NUWC, Newport.
A series of special sessions on architectural acoustics and audio
Authors: Hoover K. Anthony , Case Alexander U.
Published: May 2015

Along with his love of concert halls, opera houses, and pipe organs that are often considered the top of the architectural acoustics food chain, Dick Campbell always shared his enthusiasm for smaller rooms, loudspeakers, computers, signal processing, and all forms of media. Daring to incorporate MIDI-driven, synthesized sounds produced through loudspeakers into the pit orchestra, Dick knew how to rabble rouse—and inspire. One legacy of his politely provocative thinking is a series of 11 special sessions—so far—started with him at the 1999 Columbus meeting, and continued to this day by the authors. The thread of related special sessions had its most recent iteration at the Fall 2014 meeting in Indianapolis, “Architectural acoustics and audio—Rooms, systems, and techniques for adapting, enhancing, and fictionalizing acoustic traits”, with 22 papers covering a wide range of ideas and concepts. A tour of these sessions’ past topics and authors reveals a rich body of work that might otherwise have been overlooked in ASA meetings without the seed planted by Dick Campbell.
Radiation torque, streaming, and viscous absorption due to orthogonal waves in slightly viscous fluids
Authors: Zhang Likun , Marston Philip L.
Published: May 2015

Torque generated by orthogonal waves in slightly viscous fluids is analyzed to explore its connection with the near-boundary viscous absorption and streaming [Zhang and Marston, J. Acoust. Soc. Am. 131, 2917–2921 (2014)]. The analysis is based on a viscous correction and beam superposition of vortex fields. The analysis reports an approximation for the torque on a compressible small solid sphere and the viscous power absorption [Eqs. (15) and (21) in Zhang and Marston]. The torque expression in the dense sphere limit recovers prior expressions using near-boundary flow and streaming analyses: [Busse and Wang, J. Acoust. Soc. Am. 69, 1634–1638 (1981)] and [Lee and Wang, J. Acoust. Soc. Am. 85, 1081–1088 (1989)]. Our analysis extends prior results to give the torque on small compressible solid spheres of finite mass. The torque does not depend explicitly on the compressibility of the sphere, but does depend on the density of the sphere. Our analysis also gives the proportional relationship between the torque and the near-boundary viscous absorption. The results are generalized to cases of standing orthogonal waves and acoustic vortex fields, and other small axisymmetric obstacles such as circular cylinders and disks. [Work supported by the 2013-14 F. V. Hunt Postdoctoral Fellowship (Zhang) and by ONR (Marston).]
Sternal vibrations reflect hemodynamic changes during immersion: Underwater ballistocardiography
Authors: Wiens Andrew D. , Carek Andrew , Inan Omer T.
Published: May 2015

Ballistocardiography (BCG) is a method for measuring the small vibrations of the body caused by the beating of the human heart. In this study, vibration measurements of the sternum for the purpose of noninvasive hemodynamic monitoring during total body immersion in water are recorded and examined for the first time. Three individuals wore a low-noise accelerometer while immersed in water of varying temperature up to the neck, and Valsalva maneuvers were performed. The resulting waveforms reveal distinct differences in signal morphology between three postures and two water temperatures, suggesting that underwater BCG could be applied in aquatic environments without a need for electrodes.
Careers in acoustics: A journey from research lab engineer to tenure-track faculty
Authors: Barnard Andrew R.
Published: May 2015

As they approach the end of their Bachelor's or Master's degree, many students ask themselves “Should I get my Ph.D. or take the money and move to industry?” There is a perception that it may be more difficult to get a job after obtaining a Ph.D. due to the dreaded “over-qualification.” I have found the opposite in my career. In this talk, I will present my story of completing my Ph.D. and moving into a position at a university research laboratory, the Applied Research Lab at Penn State, and my subsequent transition into a tenure-track faculty position in the department of Mechanical Engineering—Engineering Mechanics at Michigan Tech University. Pros and Cons of both positions will be discussed as will my view on the importance of the Ph.D. researcher in the future of academia, government, and industry. I will conclude with my advice for current and future Ph.D. students interested in research and/or academics.
Perspective from a college of engineering at a large, public research university
Authors: Atchley Anthony A.
Published: May 2015

A career at a large, public research-intensive university is the gateway to a life-long opportunity to create new knowledge, develop realistic solutions to the world's greatest challenges, influence young minds, educate the next generation of leaders, and service society. The value proposition for such a privileged career opportunity, however, requires a life-long commitment to excellence, self-improvement, and reinvention. This presentation, based upon the author's experience as a faculty member, graduate program chair, and senior college-level administrator, is aimed at students who are considering faculty positions at such institutions. It will address getting the most out of your Ph.D. program and post-doctoral experience; the critical first few years as a faculty member; balancing the demands of and integrating teaching, research, and service; becoming skilled at writing proposals and desseminating research results; qualities you should seek in an institution you are considering and questions you should ask when interviewing.
Preparing for a career in academia: Managing students in research
Authors: Gee Kent L. , Neilsen Tracianne B. , Sommerfeldt Scott D. , Leishman Timothy W.
Published: May 2015

A new faculty member faces challenges associated with meeting and balancing various teaching, research, and citizenship demands. This includes managing students as part of developing a research program. Despite the vital importance of this skill, effective employee management is not something a student inherently learns in graduate school nor does it often receive attention as part of new faculty development workshops. This presentation discusses lessons learned regarding research student management. These include setting a scholarly goal at the outset with specific result-driven milestones and clear expectations of the “end game,” adopting a management style that is best suited to each student’s personality, adapting the project where possible to student strengths, and helping them learn to write as early as possible. Graduate students can be trained to become effective peer mentors of undergraduate students, increasing both a sense of teamwork and overall productivity. New faculty members will benefit from actively seeking mentorship by more experienced colleagues who have successfully built student-based research programs.
Coupling of drumhead vibrations: Experimental and numerical analysis
Authors: Worland Randy , Boe Benjamin
Published: May 2015

Many musical drums, such as snare drums, bass drums, and tom toms, consist of two stretched membranes at opposite ends of a cylindrical shell. Vibrations of the two heads are coupled acoustically by the enclosed air and mechanically by the shell itself. The degree of coupling varies with modal frequency and shape, and depends on several factors including the geometry of the drum shell (diameter and length) and the tensions of the two heads. Experimental measurements of coupled vibrations on drums of various sizes have been made using an electronic speckle-pattern interferometer to image the deflection shapes, amplitudes, and relative phases of both heads simultaneously. These measurements are compared with a finite element model of the system that illuminates the role of the vibrational patterns of the enclosed air in the coupling process.
From laboratory to concert hall: The invention and production of a new drum tuning system
Authors: Krishnamurthy Rohan
Published: May 2015

I discuss the motivations behind the invention and production of my new drumhead tuning system. The design originated with the mridangam, an ancient and popular pitched drum from South India, which has been constructed the same way for centuries. The mridangam is notoriously difficult to tune and replace drumheads, which consists of multiple layers of leather and a complex iron oxide and starch loading. My new design makes tuning and head replacement more user-friendly and durable, and can be applied to any drum that needs to be fine-tuned. I present my research comparing the acoustics of the traditional mridangam design with my new design. I also explore the challenges and opportunities involved in the international manufacturing process that is currently underway. The presentation concludes with an interactive performance on the mridangam.