bluuebunny/crossref_metadata_2025 huggingface dataset:
On the number of channels needed to classify vowels: Implications for cochlear implants
Authors: Fourakis Marios , Hawks John W. , Davis Erin
Published: October 2013

In cochlear implants the incoming signal is analyzed by a bank of filters. Each filter is associated with an electrode to constitute a channel. The present research seeks to determine the number of channels needed for optimal vowel classification. Formant measurements of vowels produced by men and women [Hillenbrand et al., J. Acoust. Soc. Am. 97, 3099–3111 (1995)] were converted to channel assignments. The number of channels varied from 4 to 20 over two frequency ranges (180–4000 and 180–6000 Hz) in equal bark steps. Channel assignments were submitted to linear discriminant analysis (LDA). Classification accuracy increased with the number of channels, ranging from 30% with 4 channels to 98% with 20 channels, both for the female voice. To determine asymptotic performance, LDA classification scores were plotted against the number of channels and fitted with quadratic equations. The number of channels at which no further improvement occurred was determined, averaging 19 across all conditions with little variation. This number of channels seems to resolve the frequency range spanned by the first three formants finely enough to maximize vowel classification. This resolution may not be achieved using six or eight channels as previously proposed. [Work supported by NIH.]
Variability in the clear speech intelligibility advantage
Authors: Konopka Kenneth , Smiljanic Rajka , Bradlow Ann
Published: October 2013

The overall intelligibility advantage for sentences produced in clear versus conversational speech is well-documented. This study looked at recognition accuracy across words in early and late positions in semantically anomalous and meaningful sentences spoken in clear versus conversational speaking styles. For both sentence types, the results showed the expected overall intelligibility advantage for clear speech over conversational speech. For the semantically anomalous sentences, in both speaking styles, a decline in keyword identification rate was observed with words earlier in the sentence being more accurately recognized than words later in the sentence. Furthermore, the intelligibility advantage for clear over conversational speech remained relatively constant across word positions. For the meaningful sentences, the decline in keyword identification rate across word positions was observed for conversational speech only. Meaningful sentences spoken in clear speech yielded a high, relatively stable word identification rate across position-in-sentence, resulting in a larger clear speech intelligibility benefit for words late in the sentence than for words early in the sentence. These results suggest that for typical meaningful sentences, the acoustic-phonetic enhancements of clear speech and the availability of semantic-contextual information combine to ‘‘boost’’ the intelligibility of words in late sentence positions.
Landmark analysis of clear and conversational speaking styles
Authors: Boyce Suzanne , Bradlow Ann , MacAuslan Joel
Published: October 2013

Speakers appear to adjust speech production according to tradeoffs between intelligibility and economy of effort [Lindblom (1992)]. Recently, there has been much interest in investigation of differences between the clear style of speech addressed to disadvantaged listeners (non-native speakers, hearing impaired listeners, etc.) and ordinary, or conversational speaking style. Clear speech has been shown to be more intelligible across a wide range of listener types [Bradlow et al., (2002); Bradlow et al., (2003)], but the full range of parameters of variation remain undetermined. Recently also, the use of abrupt changes in the speech signal, i.e., acoustic landmarks, as an organizing principle for speech recognition has garnered attention [Espy-Wilson (2005)]. Using a landmark analysis procedure based on that of Stevens (1991) and Liu (1995), we present evidence that clear and conversational speaking styles can be distinguished in terms of the distribution of particular clusters of landmarks, corresponding very roughly to syllable-sized units. The implications of this differential distribution of landmarks across speaking styles for the organization of speech production will be discussed.
Testing theories of vowel inherent spectral change
Authors: Morrison Geoffrey Stewart , Nearey Terrance M.
Published: October 2013

Models which include information about vowel inherent spectral change (VISC) have higher correct classification rates, and greater correlation with human response patterns, compared to models which only include static spectral information. Three hypotheses have been proposed as to the aspect of VISC which is relevant for human perception. All three agree that the initial target (e.g., F1 and F2 values at the beginning of the vowel) is important. The dual-target hypothesis states that the final target (e.g., F1 and F2 values at the end of the vowel) is the other relevant factor. The target-plus-slope hypothesis states that it is the rate of change in spectral values over time that is relevant. The target-plus-direction hypothesis states that only the direction of formant movement (e.g., in an F1–F2 plane) is relevant. Synthetic /e/−/I /−/ε/ stimuli with a fixed initial target but varying final target, slope, direction, and duration were identified by monolingual Western Canadian English listeners. Models of the listeners perception were parametrized according to the three hypotheses. Results indicate that the final−target model outperformed the slope modal. Neither the linear−final−target model nor the direction model clearly outperformed the other, but a final−target model including a cubic term was superior.
The perceptual relevance of locus equations
Authors: Rhone Ariane E.
Published: October 2013

Locus equations reflect the linear relationship between the second formant (F2) at vowel onset and midvowel nucleus as a function of place of articulation for voiced stop consonants. Locus equations have been shown to provide a robust stop-place categorization metric across a variety of languages. However, there is a discrepancy between traditional locus equation calculations and data from human perception studies. While locus equations are derived from two points in the speech signal that are separated by 60–110 ms, listeners are capable of categorizing English voiced stops when presented with as little as the initial 10–30 ms of stop-vowel syllables. In order to investigate the perceptual relevance of the locus equation, 20 English speakers read 150 /CVt/ syllables (/b/, /d/, or /g/ in one of ten vowel contexts repeated five times) in a carrier phrase. F2 measurements were made at vowel onset and at each glottal pulse up to and including the traditional midvowel nucleus. In addition to expected replication of previous results, this research will establish at which point in the vowel stable and distinct locus equations emerge and the relation of that point to place categorization by human listeners.
The grain size of auditory mismatch response in speech perception
Authors: Zhang Yang , Kuhl Patricia , Imada Toshiaki , Imada Toshiaki , Kotani Makoto
Published: October 2013

This phonetic study examined neural encoding of within-and cross- category information as a function of language experience. Behavioral and magnetoencephalography (MEG) measures for synthetic /ba–wa/ and /ra–la/ stimuli were obtained from ten American and ten Japanese subjects. The MEG experiments employed the oddball paradigm in two conditions. One condition used single exemplars to represent the phonetic categories, and the other introduced within-category variations for both the standard and deviant stimuli. Behavioral results showed three major findings: (a) a robust phonetic boundary effect was observed only in the native listeners; (b) all listeners were able to detect within-category differences on an acoustic basis; and (c) both within- and cross- category discriminations were strongly influenced by language experience. Consistent with behavioral findings, American listeners had larger mismatch field (MMF) responses for /ra–la/ in both conditions but not for /ba–wa/ in either. Moreover, American listeners showed a significant MMF reduction in encoding within-category variations for /ba–wa/ but not for /ra–la/, and Japanese listeners had MMF reductions for both. These results strongly suggest that the grain size of auditory mismatch response is determined not only by experience-dependent phonetic knowledge, but also by the specific characteristics of speech stimuli. [Work supported by NIH.]
The role of fundamental frequency and formants in the perception of speaker sex
Authors: Hillenbrand James M.
Published: October 2013

The purpose of this study was to determine the relative contributions of fundamental frequency (F0) and formants in controlling the speaker-sex percept. A source-filter synthesizer was used to create four versions of 25 sentences spoken by men: (1) unmodified synthesis; (2) F0 only shifted up toward values typical of women; (3) formants only shifted up toward values typical of women; and (4) both F0 and formants shifted up. Identical methods were used to generate four comparable versions of 25 sentences spoken by women (e.g., unmodified synthesis, F0 only shifted down toward values typical of men, etc.). Listening tests showed: (1) perceived talker sex for the unmodified synthesis conditions was nearly always correct; (2) shifting both F0 and formants was usually effective (∼82%) in changing the perceived sex of the utterance; (3) shifting either F0 or formants alone was usually ineffective in changing the perceived sex of the utterance. Both F0 and formants are apparently needed to specify speaker sex, though even together these cues are not entirely effective. Results also suggested that F0 is just slightly more important than formants, despite the fact that the male–female difference in F0 is proportionally much larger than the difference in formants. [Work supported by NIH.]
Backward masking for speech and tones
Authors: Paumen Allison L. , Schlauch Robert S. , Windsor Jennifer
Published: October 2013

The purpose of this research was to determine if listeners who have difficulty with backward masking for tones in noise will also have difficulty recognizing speech sounds in noise that is presented in a backward-masking paradigm. To achieve this goal, backward masking for tones (1.0 kHz) and for speech (vowel-constant syllables) was measured in a sample of children and adults. Participants included four adults, and five children ranging in age from 8 to 13 years. Results show a significant correlation between tonal thresholds and speech recognition performance in the presence of a backward masker. There was large individual variability, with some of this variance accounted for by age. [Work supported by Research Experience for Undergraduates (REU) Program, University of Minnesota.]
The interaction of acoustic and linguistic grouping cues in auditory object formation
Authors: Shapley Kathy , Carrell Thomas
Published: October 2013

One of the earliest explanations for good speech intelligibility in poor listening situations was context [Miller et al., J. Exp. Psychol. 41 (1951)]. Context presumably allows listeners to group and predict speech appropriately and is known as a top-down listening strategy. Amplitude comodulation is another mechanism that has been shown to improve sentence intelligibility. Amplitude comodulation provides acoustic grouping information without changing the linguistic content of the desired signal [Carrell and Opie, Percept. Psychophys. 52 (1992); Hu and Wang, Proceedings of ICASSP-02 (2002)] and is considered a bottom-up process. The present experiment investigated how amplitude comodulation and semantic information combined to improve speech intelligibility. Sentences with high- and low-predictability word sequences [Boothroyd and Nittrouer, J. Acoust. Soc. Am. 84 (1988)] were constructed in two different formats: time-varying sinusoidal sentences (TVS) and reduced-channel sentences (RC). The stimuli were chosen because they minimally represent the traditionally defined speech cues and therefore emphasized the importance of the high-level context effects and low-level acoustic grouping cues. Results indicated that semantic information did not influence intelligibility levels of TVS and RC sentences. In addition amplitude modulation aided listeners’ intelligibility scores in the TVS condition but hindered listeners’ intelligibility scores in the RC condition.
Optimal sonar tactics over uncertain sediments
Authors: DelBalzo Donald R. , Powers William J. , Cole Bernie F.
Published: October 2013

Tactical patterns for monostatic sensors were developed during the Cold War for deep, uniform underwater environments, where a simple median detection range defined a fixed spacing between search ladder legs. Acoustic conditions in littoral environments are so complex that spatial variability of bottom sediment properties destroys the simple homogeneous assumption associated with standard tactical search concepts. Genetic algorithms (GAs) have been applied to this problem to produce near-optimal, non-standard search tracks for monostatic mobile sensors that maximize probability of detection in such inhomogeneous environments. The present work describes a new capability called SPEAR (search planning with environmentally adaptive response) that adds tactical adaptation to search paths in a complex, littoral environment, as new in situ backscattering and bottom loss information becomes available. This presentation reviews the GA approach and discusses tactical adaptation to uncertain bottom sediment properties. The results show that easily implemented dynamic changes in active pulse depression angles and frequencies can produce significant improvement in detection performance in a complex littoral area. [Work supported by NAVSEA.]
Mode-based adaptive processing in uncertain environments
Authors: Velankar Manish R. , Zurk Lisa M.
Published: October 2013

Previous work explored the advantage of decomposing an acoustic field into normal modes and selecting appropriate modal subspaces. One primary motivation was the ability to separate surface sources from submerged sources for subsequent matched field processing. However, it was found that for many shallow environments, the modal subspaces are not sufficiently separated for adequate interference removal through filtering. This problem was further exacerbated in uncertain environments when details of the channel are unknown. In this paper, the addition of adaptive beam-forming techniques will be considered for the ability to detect and localize targets in the presence of surface interferers. In particular, robustness of the adaptive processing to environmental mismatch will be quantified. Schemes for providing robustness to adaptive self-nulling through modal filtering will be discussed and presented.
Confidence intervals for low probability for false alarms and probability for a miss at low values based small sample space support
Authors: Baggeroer Arthur
Published: October 2013

When using ROCs (receiver operating characteristics) based upon experimental data derived from either experimental or simulated data, there is a tendency to concentrate on the high values of PFA and PM (miss probability) in the middle of the ROC figure. Nevertheless, most good systems want to have a performance near the upper left of an ROC (low PFA, low PM) and this is where results based upon finite sample support have the largest proportional errors. While this may now be an artifact that ‘‘probability paper’’ is no longer routinely used, fitting a curve through these regions is almost always misleading unless the sample support is very large. The problem is fundamentally one of fitting the ‘‘tail’’ of a distribution with little data. Various methods from probability such as ‘‘Chi squared’’ and Kolmogorov-Smirnov test can be used, but they almost always lead to rejection being tested in this low probability region. Here, we use an approach based upon ‘‘Chernov tilted densities’’ to capture the uncertainty of predictions in these regions when there is sparse, or small, sample support.
Spectral coupled mode approach to three-dimensional propagation and reverberation in two-dimensional, range-dependent environments
Authors: Luo Wenyu , Schmidt Henrik
Published: October 2013

The use of spectral decomposition to 3D propagation and reverberation in 2D range-dependent environments is well established [J. Fawcett and T. Dawson, J. Acoust. Soc. Am. 88, 1913 (1990)]. The resulting 2D Helmholtz equation for each value of the separation variable can be solved by any available two-way propagation model, e.g., wave number integration [H. Fan and H. Schmidt, J. Acoust. Soc. Am. 93, 2322 (1993)] or the parabolic equation [G. J. Orris and M. D. Collins, J. Acoust. Soc. Am. 96, 1725 (1994)]. However, these approaches are computationally intensive for realistic propagation problems due to the large number of solutions required to adequately sample the spectral integral kernel. However, if the two-way problems are formulated in terms of coupled modes, as has been suggested for cylindrical seamount problems by Taroudakis [Proceedings of the 14th IMACS World Congress (1994)], the resulting modal eigenvalue problems can be shown to be independent of the separation variable and therefore have to be solved only once, leaving only the mode coupling to be handled separately for each value of the separation variable. This approach has been efficiently implemented using a two-way, modified version of the csnap single-scatter coupled-mode code for the 2D problems. The code has been validated by comparison to exact 2D solutions for range-independent problems, and applied to a wide range of shallow-water propagation problems, and to modeling of diffraction around cylindrical seamounts. The paper will describe the modeling approach and its numerical implementation, and demonstrate and discuss the significance of 3D propagation and reverberation effects for such problems.
Mode extraction from a radially accelerating cw source in shallow water
Authors: Walker Shane C. , Roux Philippe , Kuperman William A.
Published: October 2013

Recently a broadband method was introduced for extracting the depth dependence of the modes by filtering them according to their wave number spectrum. Here, a method is introduced for using a moving narrow-band source to extract the modes over a partial-water-column spanning vertical line array. Because the modes from a moving cw source are Doppler shifted in direct relation to their radial wave numbers and the radial velocity of the source, their depth dependence can be isolated directly in the frequency domain within the limits of the frequency resolution. Interestingly, the unambiguous relation between measured time and source range directly relates the frequency resolution to the wave number resolution. Thus, the range aperture covered by the source determines the extraction limits. Because a large aperture is required for low-order mode extraction, radial accelerations of non-end-fire sources subject to currents, wind, and waves tend to limit the usable aperture to an impractical extent. As a result, a technique is demonstrated to compensate for the time-dependent Doppler shift from a radially accelerating source. The technique is applied to simulation, laboratory, and ocean data.
Iso-deviant 2D gridding with efficient adaptive gridder for littoral environments (EAGLE)
Authors: Rike Erik R. , DelBalzo Donald R.
Published: October 2013

Transmission loss (TL) computations in littoral areas require a dense spatial and azimuthal grid to achieve acceptable accuracy and detail. The computational cost of accurate predictions led to a new concept, OGRES (Objective Grid/Radials using Environmentally-sensitive Selection), which produces sparse, irregular acoustic grids, with controlled accuracy. Recent work to further increase accuracy and efficiency with better metrics and interpolation led to EAGLE (Efficient Adaptive Gridder for Littoral Environments). On each iteration, EAGLE produces grids with approximately constant spatial uncertainty (hence, iso-deviance), yielding predictions with ever-increasing resolution and accuracy. The EAGLE point-selection mechanism is tested using the predictive error metric and 2D synthetic data sets created from combinations of simple signal functions (e.g., polynomials, sines, cosines, exponentials), along with white and chromatic noise. The speed, efficiency, fidelity, and iso-deviance of EAGLE are determined for each combination of signal, noise, and interpolator. The results show significant efficiency enhancements compared to uniform grids of the same accuracy. [Work sponsored by NAVAIR.]
The environmental, health, and safety issues of acoustical materials: A strategy for finding, using, and evaluating information effectively
Authors: Bischel Marsha S.
Published: October 2013

Concern over the safety of our indoor environments has increased in recent years. The definition of safety has also evolved to include not just life safety issues such as fire, but issues such as mold growth, toxins, the emission of volatile organic compounds, seismic concerns, and ergonomic issues. Consequently, the understanding of product safety has become increasingly more complex. Simultaneously, there has been an explosion in the number of products available to specifiers, due largely to access to the World Wide Web by international manufacturers of all sizes. Some of these manufacturers may be unable to test all aspects of product safety, or simply may be unaware of safety regulations. Specifiers can no longer assume a product is inherently safe and must do their own evaluations of product safety attributes. This paper will lay out a basic methodology for finding, using, and evaluating environmental, health, and safety information on acoustical products in an effective manner.
Acoustical products used as interior finish materials: Product testing and requirements
Authors: Sloan Dwayne E.
Published: October 2013

This paper will focus on the test methods, requirements, and code specifications on acoustical products when used as interior finish materials. The content will discuss the test methods and the interpretation of results of key Standards such as ASTM E84, UL 723, ASTM E136, ASTM C423, and others. The content will also discuss the code differences between Class A, B, and C materials and other important aspects of the governing building codes.
Seasonal and diurnal calling patterns of Ross and leopards
Authors: Rogers Tracey L. , Rowney Gayle A. , Ciaglia Michaela B. , Cato Douglas H.
Published: October 2013

The temporal calling patterns of two Antarctic pack ice seals, the leopard and Ross seal, were examined. This included seasonal onset and decline of calling (coinciding with their breeding season) as well as diurnal changes. Understanding of calling behavior has important implications for acoustic surveying, since this allows the number of calls to be related to an index of the number of animals present and to estimate abundance. The monthly changes in diurnal calling and haul-out patterns (measured via satellite telemetry) were compared. Underwater acoustic recordings were made between 14 October 2003 and 10 January 2004 off Mawson, Eastern Antarctica (660 44.243S and 690 48.748E). Recordings were made using an Acoustics Recording Package (ARP by Dr. John Hildebrand, Scripps Institute of Oceanography, La Jolla, CA) which is designed to sit on the seafloor and passively record acoustic signals. The package was deployed at a depth of 1320.7 m. The sampling rate was 500 Hz and the effective bandwidth from 10 to 250 Hz, covering the bandwidth of only the low-frequency calls of the Ross and leopard seal.
Diel and seasonal patterns of underwater sounds by Weddell seals, leopard seals, and killer whales in the Antarctic: When it’s adaptive to be quiet
Authors: Mindach Debrah , Thomas Jeanette
Published: October 2013

Automated underwater recordings taken during the austral breeding season of the Weddell seal (Leptonychotes weddellii) in Antarctica also provided data on the vocalizations of predators in the area; leopard seals (Hydrurga leptonyx) and killer whales (Orcinus orca). Weddell seals inhabit fast ice areas to give birth, mate, and molt. Near the end of the breeding season in December the fast ice often breaks out and the two pack ice predators are able to move near the Weddell seal colonies and prey on them, especially pups. Recordings were taken continuously for a 2.5-min period each hour from mid-October 1977 and late-January 1978 at Hutton Cliffs and South Turtle Rock Crack, in McMurdo Sound. The leopard seals increased their trill calls when killer whales came into the area as evidenced by an increase in their frequency-modulated squeak calls. Weddell seals decreased their vocalization rate dramatically (∼10 sounds/min) compared to during the peak of the breeding season (∼75 sounds/min). Perhaps by being quiet, Weddell seals do not attract predators to their area.
Advantages of time reversal acoustic focusing system in biomedical applications
Authors: Sutin Alexander , Sarvazyan Armen
Published: October 2013

The development and biomedical applications of time reversal acoustics (TRA) systems for focusing and manipulating ultrasound beams are reviewed. The TRA focusing system (TRA FS) is capable to deliver ultrasound energy to the chosen region in highly inhomogeneous medium (including soft tissues and bones) with focusing efficacy hardly achievable using conventional phased array transmitters. TRA FS is able to focus and stir ultrasound beams in a 3-D volume using just a few piezoceramic transducers glued to the facets an aluminum block. Another advantage of TRA FS is its ability to produce pulses with arbitrary waveforms in a wide frequency band. A custom-designed compact multichannel TRA system operating in a wide frequency range from 0.01 to 10 MHz has been developed. Measurements of TRA field structure were conducted in a large variety of inhomogeneous tissue phantoms and ex vivo bones and soft tissues. Principles of TRA focusing optimization based on acoustical properties of the resonator material, parameters of the sonicated medium, and the coupling of the TRA resonator with the medium were developed and applied in the tested TRA systems. [Work was supported by NIH.]
Asymmetric oscillation of adherent targeted microbubbles
Authors: Zhao Shukui , Ferrara Katherine W. , Kruse Dustin E. , Dayton Paul A.
Published: October 2013

Recent development of molecular imaging with targeted ultrasound contrast agents calls for a selective and sensitive detection method for adherent targeted agents, which depends on our understanding of the response of adherent agents to ultrasound interrogation. Here, asymmetric oscillation of targeted microbubble contrast agents adherent to a cellulose microtube was studied with a high-speed camera and compared to the oscillation of free-floating microbubbles. The microbubbles were biotinylated in order to bind to avidin on the inside of the microtube. A 1.5-MHz, three-cycle ultrasound pulse was used to insonify the microbubbles. Adherent microbubbles were observed to oscillate asymmetrically in the plane normal to the boundary and nearly symmetrically in the plane parallel to the boundary, with a maximum expansion in each dimension significantly smaller for bound than free microbubbles (p<2E−5 and p<0.015, respectively). The observed oscillation period of adherent microbubbles was significantly different from that of free microbubbles (p<0.0015) with the former closer to the period of the driving pulse. Asymmetric oscillation led to shape instability and with sufficient acoustic pressure a jet was observed traveling toward the boundary and fragmentation of the adherent microbubbles was observed. A fraction of the resulting fragments were observed to float freely in solution.
A transfer matrix formulation of an electromechanical Helmholtz resonator
Authors: Liu Fei , Cattafesta Lou , Sheplak Mark , Horowitz Stephen , Nishida Toshi
Published: October 2013

An electromechanical Helmholtz resonator (EMHR) employing a compliant piezoelectric composite backplate is under development at the University of Florida. The acoustic impedance of the EMHR is made tunable and additional degrees of freedom (DOF) are added by coupling the piezoelectric composite diaphragm to a passive electrical shunt network. A formula of the transfer matrix is subsequently derived to predict the behavior of the EMHR. The theoretical aspects of electromechanical tuning are then reviewed and proof-of-concept experimental data are presented for a variety of resistive, capacitive, and inductive shunts in a normal-incidence plane wave tube (PWT). For resistive and capacitive shunt circuits, the resonator is shown to be a two DOF system, and short-circuit and open-circuit loads define the limits of the tuning range. There is approximately a 9% tuning limit under these conditions for the resonator configuration studied. An inductive shunt load results in a three DOF system with an enhanced tuning range of over 20% that is not restricted by the short-circuit and open-circuit limits.
Acoustic levitation
Authors: Hansen Uwe J.
Published: October 2013

A speaker, driven by an amplified audio signal is used to set up a standing wave in a 3b-ft-long, 4-in.-diam transparent tube. Initially the tube is oriented horizontally, and Styrofoam packing peanuts accumulate near the pressure nodes. When the tube is turned to a position with the axis oriented vertically, the peanuts drop slightly, until the gravitational force on the peanuts is balanced by the force due to the sound pressure, at which point levitation is observed. Sound-pressure level measurements are used to map the air column normal mode pattern. Similarly, standing waves are established between an ultrasonic horn and a metal reflector and millimeter size Styrofoam balls are levitated.
Demonstration of nonlinear effects in acoustic landmine experiments using a clamped-plate soil oscillator
Authors: Korman Murray S. , Bond Emilia
Published: October 2013

Current nonlinear experiments involving the detection of plastic landmines using acoustic-to-seismic coupling have been developed from Sabatier’s (linear) and Donskoy’s (nonlinear) earlier methods. A laboratory apparatus called the soil-plate oscillator has been developed at the National Center for Physical Acoustics, and later at the U.S. Naval Academy, to model acoustic mine detection. The apparatus consists of a thick-walled cylinder filled with sifted homogeneous soil resting on a thin elastic plate that is clamped to the bottom of the column. It represents a good simplified physical model for VS 1.6 and VS 2.2 inert anti-tank plastic buried landmines. Using a loudspeaker (located over the soil) that is driven by a swept sinusoid, tuning curve experiments are performed. The vibration amplitude versus frequency is measured on a swept spectrum analyzer using an accelerometer located on the soil-air interface or under the plate. The backbone curve shows a linear decrease in peak frequency versus increasing amplitude. A two-tone test experiment is performed using two loudspeakers generating acoustic frequencies (closely spaced on either side of resonance, typically ∼100 Hz). A rich vibration spectrum of combination frequency tones (along with the primaries) is observed which is characteristic of actual nonlinear detection schemes.
Vibro-acoustic prediction of low-range planetary gear noise of a automotive transfer case
Authors: Narayanaswamy Ravi , Glynn Charles D.
Published: October 2013

This paper discusses a practical approach to predict low range planetary gear noise in an automotive transfer case using commercial numerical codes. Dynamic responses of the planetary gear set are calculated using a 2D finite element/contact mechanics model. These responses are used as boundary conditions to calculate surface velocities on the transfer case housing using model frequency response analysis. Subsequently, the surface velocities are used in a vibro-acoustic model to predict acoustic responses of the transfer case. The predicted acoustic responses are compared to experimental measurements conducted in a hemianechoic chamber. It is shown that the predictions are in reasonable agreement with the experiments and the approach enables designers to obtain required information on acoustic responses of the transfer case in a timely and cost-efficient manner.
Demonstrating adequacy of railroad warnings: A case study
Authors: Erdreich John , DiFrancesco Victor
Published: October 2013

Frequently a jury is asked to evaluate a claim that a device provided adequate warning of a hazardous condition. Although there is extensive research on which basis an expert may evaluate such claim, the layman is unprepared to integrate such information into a decision. Previous attempts to produce courtroom demonstrations of warnings have been easily challenged by opposing experts. In a recent case involving a pedestrian accident on a railroad right-of-way we produced a jury demonstration that was accepted by the court, was not challenged effectively by opposing counsel, and communicated effectively with the jury. This paper describes a demonstration that incorporated binaural recording and presentation with a synchronized video orientation and simulation. We will present an excerpt of the demonstration.
Health Insurance Portability and Accountability Act (HIPAA) legislation and its implication on speech privacy design in health care facilities
Authors: Tocci Gregory C. , Storch Christopher A.
Published: October 2013

The Health Insurance Portability and Accountability Act (HIPAA) of 1996 (104th Congress, H.R. 3103, January 3, 1986), among many things, individual patient records and information be protected from unnecessary issue. This responsibility is assigned to the U.S. Department of Health and Human Services (HHS) which has issued a Privacy Rule most recently dated August 2002 with a revision being proposed in 2005 to strengthen penalties for inappropriate breaches of patient privacy. Despite this, speech privacy, in many instances in health care facilities need not be guaranteed by the facility. Nevertheless, the regulation implies that due regard be given to speech privacy in both facility design and operation. This presentation will explore the practical aspects of implementing speech privacy in health care facilities and make recommendations for certain specific speech privacy situations.
A novel ultrasonic method for characterizing suspensions of nanoparticles
Authors: Africk Steven
Published: October 2013

The Ultrasonic Pulsed Doppler (USPD) technique for characterization of nanoparticle suspensions is described. This method uses a single transducer as both source and receiver of pulsed ultrasound to measure backscattered energy from suspended and moving particles. Particle motion can be provided mechanically (e.g., by stirring or unidirectional flow) or by acoustic streaming generated by the interrogating acoustic field itself. The only requirement on sample volume is that it be larger than several cubic millimeters. It has been demonstrated that the system can measure particle concentration for Islets of Langerhans (on the order of 150 μm in diameter), cells (20 μm), emulsions (150 nm), carbon nanotubes (10 nm diameter), and polymer beads as small as 40 nm. Preliminary data suggest that the system can detect and measure dendrimers on the order of 4 nm in diameter. Other potential applications include measurement of particle size distribution, suspension viscosity, sample purity, and particle compressibility. The system concept is proposed as a research tool and is under development as a quality control device for nanomanufacturing in batch mode or as a monitor of a stream with particles. [Work supported by NIH.]
Ultrasonic scattering in two-phase polycrystalline media
Authors: Liu Dalie , Turner Joseph A.
Published: October 2013

Successful processing of materials by powder sintering relies on the creation of strong interparticle bonds. During certain critical stages of the sintering process, the medium may be modeled as two phases consisting of the particles and a surrounding matrix. Ultrasonic methods have been proposed as a potential tool for monitoring such sintering processes. Thus, an understanding of the propagation and scattering of elastic waves in two-phase solids is of fundamental importance to these monitoring techniques. Here, a combined theoretical and numerical approach is used to address this problem. Ultrasonic attenuation and diffuse backscatter are studied theoretically using elastodynamic and stochastic wave theory, based on the spatial statistics of the density and Lamé parameters of the materials constituents under assumptions of statistical homogeneity and statistical isotropy. The numerical models are based on Voronoi polycrystals surrounded by a matrix of different material properties. Elastic wave simulations using the finite-element method (FEM) are then created to examine the influence of the grain size, wave type, and material statistics. The numerical results are compared with the attenuation theory proposed. The results presented are anticipated to impact the monitoring of materials processing of important engineering materials. [Work supported by U.S. DOE.]
Vibration transfer mobility measurements using maximum length sequences
Authors: Singleton Herbert L.
Published: October 2013

Vibration transfer mobility measurements are required under Federal Transit Administration guidelines when developing detailed predictions of ground-borne vibration for rail transit systems. These measurements typically use a large instrumented hammer to generate impulses in the soil. These impulses are measured by an array of accelerometers to characterize the transfer mobility of the ground in a localized area. While effective, these measurements often make use of heavy, custom-engineered equipment to produce the impulse signal. To obtain satisfactory signal-to-noise ratios, it is necessary to generate multiple impulses to generate an average value, but this process involves considerable physical labor in the field. To address these shortcomings, a transfer mobility measurement system utilizing a tactile transducer and maximum length sequences (MLS) was developed. This system uses lightweight off-the-shelf components to significantly reduce the weight and cost of the system. The use of MLS allows for adequate signal-to-noise ratio from the tactile transducer, while minimizing the length of the measurement. Tests of the MLS system show good agreement with the impulse-based method. The combination of the cost savings and reduced weight of this new system facilitates transfer mobility measurements that are less physically demanding, and more economical when compared with current methods.
Relative saliency of pitch versus phonetic cues in infancy
Authors: Cardillo Gina , Kuhl Patricia , Sundara Megha
Published: October 2013

Infants in their first year are highly sensitive to different acoustic components of speech, including phonetic detail and pitch information. The present investigation examined whether relative sensitivity to these two dimensions changes during this period, as the infant acquires language-specific phonetic categories. If pitch and phonetic discrimination are hierarchical, then the relative salience of pitch and phonetic change may become reversed between 8 and 12 months of age. Thirty-two- and 47-week-old infants were tested using an auditory preference paradigm in which they first heard a recording of a person singing a 4-note song (i.e., ‘‘go-bi-la-tu’’) and were then presented with both the familiar and an unfamiliar, modified version of that song. Modifications were either a novel pitch order (keeping syllables constant) or a novel syllable order (keeping melody constant). Compared to the younger group, older infants were predicted to show greater relative sensitivity to syllable order than pitch order, in accordance with an increased tendency to attend to linguistically relevant information (phonetic patterns) as opposed to cues that are initially more salient (pitch patterns). Preliminary data show trends toward the predicted interaction, with preference patterns commensurate with previously reported data. [Work supported by the McDonnell Foundation and NIH.]
Intelligibility and clarity of clear and conversational speech by children with implants and hearing aids
Authors: Carney Arlene E. , Nie Yingjiu , Main Jennifer , Carney Edward , Higgins Maureen B.
Published: October 2013

Studies of clear versus conversational speech have shown perceptual and acoustic differences. The basic premise is that the speaker understands the direction to speak more clearly, and translates the direction to speech motor acts. Children with hearing losses receive intervention during which they are instructed to use their best speech. The purpose of this study was to determine: (1) whether hearing-impaired children’s intelligibility changed with directions to use better speech, and (2) whether these children’s speech was judged to be clearer when they had intended to produce clear speech. There were two groups of speakers: 14 deaf children with cochlear implants and 7 hard-of-hearing children with hearing aids. Each produced ten short sentences using typical speech, better speech, and best speech. All sentences were presented to a total of 189 adult listeners with normal hearing who wrote down what they heard. Hard-of-hearing children had average speech intelligibility of 98%; those with implants averaged 66%. Both groups had very small increases across conditions. All sentences in three speech conditions were presented in a paired-comparison task to ten additional listeners. Results of clarity judgments will be discussed in relation to the relatively small changes in speech intelligibility. [Research supported by NIH.]
Importance of low-frequency on understanding interrupted speech: Sentence recognition of hearing-impaired (HI) and normal-hearing (NH) listeners
Authors: Jin Su-Hyun , Nelson Peggy
Published: October 2013

In a recent study of HI listeners’ speech perception in noise (Jin and Nelson, 2004), two main factors, low-frequency audibility and auditory filter bandwidths, were highly related to amplified sentence recognition in modulated noise. Nine young adult listeners with sensorineural hearing loss and eight young NH listeners as controls participated in the series of experiments. Amplified speech recognition of the HI listeners was equal to that of the NH listeners in quiet and in steady noise, but was significantly poorer in modulated noise. Thus, even with adequate amount of amplification, HI listeners experienced significantly less masking release from the modulated maskers. The results indicated that those listeners with greatest hearing losses in the low frequencies were poorest at speech recognition in modulated noise. Additional results from HI and NH listeners will be presented, in which we systematically vary the audibility of different frequency regions of speech by filtering. Sentences are interrupted by either speech-shaped noise or silence gap while measuring the percent of sentence recognition. The purpose of the current study is to examine the importance of low-frequency audibility for auditory segregation/integration of interrupted speech.
Effects of masking noise on vowel and sibilant contrasts in normal-hearing speakers and postlingually deafened cochlear implant users
Authors: Perkell Joseph S. , Denny Margaret , Lane Harlan , Matthies Melanie L. , Stockmann Ellen , Tiede Mark , Zandipour Majid , Vick Jennell
Published: October 2013

The role of auditory feedback in speech production was investigated by examining how speakers modify phonemic contrasts in response to increases in the noise-to-signal (N/S) level in their auditory feedback. Seven cochlear implant users and seven normal-hearing controls pronounced utterances containing the vowels IY, UW, EH, and AE and the sibilants s and SH while hearing their speech mixed with noise at seven equally spaced levels over their tolerated ranges (which were smaller for implant users than for controls). Average vowel duration and spl rose with increasing N/S, monotonically for controls and more irregularly for implant users. On the other hand, a measure of overall vowel contrast rose initially then fell with increasing N/S. The initial rise is interpreted as part of speakers attempts to maintain clarity with degraded acoustic transmission conditions. As N/S increases further, speakers can no longer detect phoneme contrasts, and economy of effort becomes an increasingly predominant influence, leading to contrast decrements. The sibilant contrast was more vulnerable to noise: the s-SH contrast distance fell over the entire range of increasing N/S. Results from implant users were more variable than from controls, especially for the sibilants. [Research supported by the NIDCD.]
Effects of speaking condition and hearing status on vowel production in postlingually deaf adults with cochlear implant
Authors: Menard Lucie , Denny Margaret , Lane Harlan , Matthies Melanie L. , Perkell Joseph S. , Stockmann Ellen , Vick Jennell , Zandipour Majid , Balkany Thomas , Polack Marek , Tiede Mark K.
Published: October 2013

This study investigates the effects of speaking condition and hearing status on vowel production by postlingually deafened adults. Thirteen cochlear implant users produced repetitions of nine American English vowels in three time samples (prior to implantation, one month, and one year after implantation); in three speaking conditions (clear, normal, and fast); and in two feedback conditions after implantation (implant processor turned on and off). Ten speakers with normal hearing were also recorded. Results show that vowel contrast, in the F1 versus F2 space, in mels, does not differ from the pre-implant stage to the 1-month stage. This finding indicates that shortly after implantation, speakers had not had enough experience with hearing from the implant to adequately retune their auditory feedback systems and use auditory feedback to improve feedforward commands. After 1 year of implant use, contrast distances had increased in both feedback conditions (processor on and off), indicating improvement in feedforward commands for phoneme production. Furthermore, after long-term auditory deprivation, speakers were producing differences in contrast between clear and fast conditions in the range of those found for normal-hearing speakers, leading to the inference that maintenance of these distinctions is not affected by hearing status. [Research supported by NIDCD.]
Perception and production of /r/ allophones improve with hearing from a cochlear implant
Authors: Matthies Melanie , Guenther Frank , Denny Margaret , Perkell Joseph , Stockmann Ellen , Vick Jennell , Tiede Mark , Lane Harlan
Published: October 2013

While variations in tongue shape for /r/ occur in different contexts, they normally result in only small changes in the primary acoustic cue (lowered F3). It was hypothesized that deaf speakers would show larger allophonic variation than normal-hearing speakers and that auditory feedback from a cochlear implant would reduce that variability. In this study, acoustic variation of stop and stop+/r/ tokens was evaluated pre- and post-implant (n=8) and once in normal-hearing controls (n=8). Measures included (1) r-variation: distance from the center of the distribution defined by the F3 transition and the value of F3 minus F2 at the /r/-vowel boundary for wabrav, wadrav, and wagrav tokens (2) vowel variation: distance from the center of F1, F2 for the second /a/ in wabav, wadav, and wagav tokens and (3) pairwise r-variation normalized by vowel variation. Pre-implant, seven of eight speakers had significantly greater normalized /r/ variation than the hearing speakers mean. Post-implant, seven of eight speakers had normalized /r/ are variation that was not different from the control mean. Implant users perception and production of stop and stop+/r/ blend productions improved; however, their /b-br/ and /g-gr/ contrast distances were still smaller one-year post-implant than the controls. [Research supported by NIDCD.]