bluuebunny/crossref_metadata_2025 huggingface dataset:
Gabriel Weinreich: The life and style
Authors: Hartmann William M.
Published: October 2013

Gabriel Weinreich (Gabi) was born in Vilna, Poland (now the capitol of Lithuania) one year prior to the founding of the Acoustical Society of America. When the second world war began in central Europe, Gabi’s family came, in serial fashion, to New York City—Gabi himself arriving in 1941. Gabi studied physics at Columbia, and received a Ph.D. in 1953 for a thesis on atomic physics directed by the legendary I. I. Rabi. He subsequently worked on fundamental properties of semiconductors, first at Bell Labs, then, starting in 1960, at the University of Michigan. In 1977 he turned his attention to the acoustics of musical instruments, mainly the piano and bowed strings. He studied all phases of the physical elements: string excitation, string vibration, coupling, and radiation. Gabi brought his special style to acoustics—a combination of theory and experiment that imaginatively imports ideas and techniques from one area of physics into another, a willingness to attack traditional problems afresh by returning to first principles, and the ability to present ideas with incisive wit and charm so that information is not only informative but is also entertaining.
A detailed experimental comparison between active and passive approaches for the reduction of total far-field radiated sound power from a point-driven simply support plate
Authors: Herdic Peter C. , Houston Brian H. , Corsaro Robert D.
Published: October 2013

Passive and active control of sound radiation from plates has been a challenging problem for a number of years where numerous surface treatments have been examined. The two most viable active surface treatments are active constrained layer damping (ACLD) and modal restructuring (MR). ACLD minimizes the total radiated power through a combination passive/active damping mechanisms as well as by applying restoring forces/moments. MR, on the other hand, achieves far-field attenuation by reducing the plates radiation efficiency through a restructuring of its mode shape. These active approaches show considerably more performance when compared to an optimized (Ross–Kerwin–Ungar) passive constraint layer damping design. The performance is evaluated by scanning near-field acoustic holography (NAH) measurements at several mode frequencies associated with strong radiation. The quantities determined via NAH include the power radiated in the half space as well as spatially dense surface motions of the plate. Both ACLD and MR show ∼50 dB reductions of total far-field radiated sound power (per unit input power). These experimental results will be discussed with particular emphasis placed on the tradeoffs between the passive and active surface treatments as well as the level of performance that can be obtained through other control approaches.
Vibration-controlled modules for use in active segmented partitions
Authors: Leishman Timothy
Published: October 2013

Active segmented partitions (ASPs) have become an important topic in the research of active sound transmission control (ASTC). Many ASTC applications require lightweight partitions, high transmission loss over a broad frequency range, and applicability to a variety of source and receiving space conditions. This paper provides theoretical, numerical, and experimental evaluations of specific ASP module configurations used to satisfy these requirements. The control objective for each is to induce global vibration control of its various transmitting surfaces through direct minimization of the normal vibration of its principal transmitting surface. Normal-incidence transmission loss estimates are based on equivalent circuit analysis and corresponding experimental measurements are made using plane wave tube techniques. The paper explains why characteristic single diaphragm configurations are unable to use this strategy effectively. It also discusses two dual diaphragm configurations that use the control scheme particularly well to produce efficient global control of their transmitting surfaces and achieve very high transmission loss over a broad frequency range. The designs facilitate incorporation into full ASP arrays and satisfy other useful criteria.
Dynamics of concerted bubble cluster collapse in shock wave lithotripsy
Authors: Pishchalnikov Yuri A. , McAteer James A. , Evan Andrew P. , Sapozhnikov Oleg A. , Cleveland Robin O. , Colonius Tim , Bailey Michael R. , Crum Lawrence A.
Published: October 2013

Cavitation bubble cluster collapse at the surface of artificial kidney stones during shock wave lithotripsy was investigated in vitro by means of multiframe high-speed photography, passive cavitation detection (PCD), and pressure waveform measurements using a fiber-optic probe hydrophone (FOPH). It was observed that after the passage of the lithotripter shock pulse the stone was covered by numerous individual bubbles. During their growth phase the bubbles coalesced into bubble clusters, with the biggest cluster at the proximal face of the stone. High-speed camera images suggested that cluster collapse started at the periphery and ended with a violent collapse in a small region in the center of the surface of the stone. Shadowgraphy resolved numerous secondary shock waves emitted during this focused collapse. Shock wave emission during cluster collapse was confirmed by PCD. Measurement with the FOPH showed that these shock waves were typically of short duration (0.2 μs). The majority of the shock waves emanating from cluster collapse were low amplitude but some shock waves registered amplitudes on the order of the incident shock pulse (tens of MPa). [Work supported by NIH DK43881, DK55674.]
Two-dimensional acoustic aerosol concentration
Authors: Meegan G. Douglas , Ilinskii Yurii A.
Published: October 2013

The detection of very dilute but dangerous biological and/or chemical aerosols can be significantly improved by densely concentrating the aerosols in a small air stream before they enter existing analyzers. Aerosol concentration can be accomplished by passing the sampled air stream through a chamber containing a sound field that forces aerosols to align themselves along a single line while the air continues to flow straight through the device. Several well-known physical mechanisms responsible for aerosol concentration include Stokes drag, Kings force, and nonlinear viscosity. However, these existing models assume one-dimensional acoustic fields and other simplifying approximations that are violated in most realistic situations. In this talk, a reformulation of the three physical mechanisms is presented that removes simplifying assumptions and describes aerosol concentration in a multi-dimensional sound field (cylindrical and Cartesian geometries). The influence of the boundary layer surrounding individual particles is included in the calculations. It was found that selective acoustic aerosol concentration (SAAC) is possible whereby aerosols in a specific particle size range can be concentrated and particles outside that size range can be excluded. Experiments will be described that convey the unique capabilities of SAAC that other methods, such as electrostatic aerosol concentration, cannot achieve.
Effects of eye-glasses, hair, headgear, and clothing on measured head-related transfer functions Part Ib
Authors: Riederer Klaus A. J.
Published: October 2013

Extensive head-related transfer function (HRTF) measurements show high HRTF repeatability, consequences of different measurement methods, and conditions covering the whole three-dimensional space [Riederer, J. Audio Eng. Soc. (Abstracts) 46, 1036 (1998), preprint 4846]. This study concentrates on specific effects on HRTFs carefully re-measured on the same Cortex dummy head applying Sennheiser KE4-211-2 microphones at its silicone putty blocked ear-canal entrances, employing 252 sound incidents including seven elevations. The effects of five different wigs (synthetic, natural, thick, thin, long and short hair) with varied hairstyles, four hats (cap, bicycle helmet, mens and womens trilby), clothes (alpaca pullover, bicycling drymax-jacket) and spectacles were investigated under 28 combinations. The influences are highly dependent on direction, frequency, and case. Clothes and eye-glasses affect minimally HRTF; hair has a stronger effect, depending on the actual hairdo (typically above 7 kHz). Hats alter intensively HRTFs (typically above 5 kHz), depending on the model. The measurements give deeper insight to the development of idiosyncratic features in binaural localization cues. The second part of the study addresses their perceptual effects [Riederer, J. Acoust. Soc. Am., this issue]. [Work supported by Graduate School of Electronics, Telecommunication and Automation; thanks to Finnish Broadcasting Company, Mr. Hellstrom; Mrs. Chen.]
Transducer placement for robustness to variations in boundary conditions for active structural acoustic control
Authors: Sprofera Joseph D. , Clark Robert L. , Gibbs Gary P. , Cabell Randolph H.
Published: October 2013

The study of control strategies aimed at the reduction of turbulent boundary layer noise transmission into the fuselage of an aircraft has been a topic of academic and industrial research for several years. In this work we focus on an approach that will attempt to address a practical application issue: the impact of uncertainty in boundary conditions on the choice of actuator and sensor locations for structural acoustic control. The selection of an optimized set of transducers and the creation of a suitably adjustable test system is used to demonstrate that robustness to bounded variations in boundary conditions of a plate is achievable in active structural acoustic control. This robustness is achieved through the optimization of transducer placement with respect to maximizing control of structural acoustic radiation over the desired range of boundary conditions. This project incorporates energy based modeling of the structure, electromechanical piezo coupling, radiation filter modeling, and control analysis through the use of Hankel Singular Value (HSV) estimates and optimization based upon the genetic algorithm. Testing in a transmission loss facility will be used to validate the selected transducer placements and demonstrate a reduction in radiated sound power. [Work supported by NASA.]
Optimal control forces for absorption and transmission through composite porous layers
Authors: Kidner Michael
Published: October 2013

A composite infinite panel consisting of a plate, a foam layer, a layer of active forces, and another foam layer could be constructed such that the absorbtion coefficient on the foam side is equal to unity and the TL is infinite. This paper derives the required active force and discusses conflicts between achieving these goals with one set of forces. The practical implications of realizing this optimal force distribution are discussed. The effect of limited power and discrete actuation of the active layer is investigated. The influence of the macroscopic properties of the foam layers on the performance of the system is also considered.
Prosodic domain-initial effects on the acoustic structure of vowels
Authors: Fox Robert Allen , Jacewicz Ewa , Salmons Joseph
Published: October 2013

In the process of language change, vowels tend to shift in ‘‘chains,’’ leading to reorganizations of entire vowel systems over time. A long research tradition has described such patterns, but little is understood about what factors motivate such shifts. Drawing data from changes in progress in American English dialects, the broad hypothesis is tested that changes in vowel systems are related to prosodic organization and stress patterns. Changes in vowels under greater prosodic prominence correlate directly with, and likely underlie, historical patterns of shift. This study examines acoustic characteristics of vowels at initial edges of prosodic domains [Fougeron and Keating, J. Acoust. Soc. Am. 101, 3728–3740 (1997)]. The investigation is restricted to three distinct prosodic levels: utterance (sentence-initial), phonological phrase (strong branch of a foot), and syllable (weak branch of a foot). The predicted changes in vowels /e/ and /ε/ in two American English dialects (from Ohio and Wisconsin) are examined along a set of acoustic parameters: duration, formant frequencies (including dynamic changes over time), and fundamental frequency (F0). In addition to traditional methodology which elicits list-like intonation, a design is adapted to examine prosodic patterns in more typical sentence intonations. [Work partially supported by NIDCD R03 DC005560-01.]
Exploration of question intonation in read American English
Authors: Syrdal Ann K. , Jilka Matthias
Published: October 2013

Several generally accepted intonational features of questions in American English have not been the subject of much empirical study: namely that wh-questions end in L-L% phrasal accents, and that their intonational contours are identical to those of declarative sentences, while yes/no questions end in H-H% phrasal accents. The study addresses the following questions about question intonation: How frequently do yes/no questions end in H-H% phrasal tones, and how often do wh-questions end in L-L% phrasal tones? How similar are the intonational contours and features of declarative sentences and wh-questions with phrase-final falls (L-L%)? How do the sentence pitch ranges of yes/no questions, wh-questions, and declarative sentences compare? Does a speaker’s characteristic pitch range affect the character or frequency of occurrence of question phrasal-tones? Speaker and utterance pitch ranges and their relation to prosodic features of pitch accents and phrasal tones were observed in yes/no and in wh-questions, and compared to a sample of simple declarative sentences spoken by the same speakers: 5 female and 3 male American English professional voice talents. The same set of 12 sentences were read by each of the 8 speakers in the same contexts. Theoretical and practical implications of the results will be discussed.
Kalman filtering with neural networks for change detection in simulated sidescan sonar data
Authors: McDowell Pamela J. , Gendron Marlin L. , McDowell Patrick M. , Ioup Juliette W. , Ioup George E.
Published: October 2013

Sidescan sonars produce acoustical imagery which is used to detect bottom objects and characterize features of the seafloor. Change detection is a method that can be used to flag new bottom objects which were not detected during previous sidescan sweeps. Improvements in object detection and classification are critically needed to improve change detection methods. Adaptive filtering techniques may be used to identify objects known or previously marked from historical data, and flag new objects detected as changed. In this study Kalman Filter techniques will be used to estimate weights for a supervised feed-forward perceptron neural net classifer. Both noise-free and noisy data are considered. Preliminary results from these techniques using simulations that model sidescan sonar data sets will be presented.
Spatial filtering techniques applied to source localization
Authors: Stotts Steven A. , Koch Robert A. , Knobles David P.
Published: October 2013

Matched-field processing outputs may be degraded by the presence of multiple sources. To isolate single sources, a spatial filtering algorithm has been developed. Element level data are transformed to beam space, filtered in bearing, then transformed back to element level data which are then used in simulated annealing inversions. The efficacy of the approach was demonstrated by comparing filtered and unfiltered ambiguity surfaces of depth, range, and bearing using a cross-correlation cost function in a simulated multisource environment with equally spaced array elements [Stotts et al., J. Acoust. Soc. Am. 113, 2217 (2003)]. Recently, this method was successfully applied to a real data set where localizations had previously been obtained using beam processing, and ground truth bottom properties have been established. Ambiguity surfaces are exhibited to demonstrate filter performance for real data. Examining the spectrum of singular values associated with the filter shows differences between equally and non-uniformly spaced elements, where a modification is required for frequencies greater than ideal. Energy conservation requirements validate filter output. Filter design details and results for both simulated and real data will be presented. Effectiveness as a function of signal-to-noise ratio, measured relative to an interferer, is also examined.
Focalization in the presence of internal waves
Authors: Collins Michael D. , Baer Ralph N.
Published: October 2013

Focalization is an approach for localizing an acoustic source in a medium with environmental uncertainties [J. Acoust. Soc. Am. 90, 1410–1422 (1991)]. With this approach, key environmental parameters are adjusted in an attempt to bring the source into focus and determine its location. This approach has proven to be effective for problems involving deterministic environmental parameters. Due to the nature of the parameter space, focalization should also be effective for problems involving uncertain stochastic parameters. Due to a parameter hierarchy in which source parameters are more important than environmental parameters, it is often possible to localize the source without determining the correct environmental parameters. This paper will investigate focalization in the presence of internal waves, which are often sufficient to cause conventional localization techniques to fail. [Work supported by ONR.]
Inversion for source levels and environmental and source track parameters
Authors: Koch Robert A. , Knobles D. P.
Published: October 2013

A methodology for simultaneous inversion for source levels, source track parameters, and environmental parameters is described. An application to acoustic data recorded on a bottom-mounted, horizontal line array at a soft-sediment, shallow-water site in the Gulf of Mexico off Port Aransas, TX is discussed. This inversion approach may be viewed as a technique for making TL measurements with sources of opportunity by a generalization of the inversion of measured TL as a function of range for geoacoustic parameters for which the source depth is known. The technique involves minimizing a cost function formed from a sum over hydrophones and frequencies of the squared difference between received levels and modeled intensities. The inversion methodology will be validated using known cw tones emitted by a towed source and demonstrated for sources of opportunity using acoustic emissions from the RV LONGHORN, the experimental platform for the experiment. [Work supported by ONR.]
Could the gunshot be heard?
Authors: Schomer Paul
Published: October 2013

Witnesses, friends and family of a man chased through a field by the police, said they heard gunshots. The man chased says that the police shot at him. The police say that no shots were fired. Could the witnesses have heard the gunshots? The main technical issues are source strength and directivity, weather effects on sound propagation, attenuation by forests, sound transmissions through walls, and signal detectability. This paper lays out the material much as the jury heard it.
Passive monitoring and localization of marine mammals in open ocean environments using widely spaced bottom mounted hydrophones
Authors: Jarvis Susan , Moretti David , Morrissey Ronald , DiMarzio Nancy
Published: October 2013

The Marine Mammal Monitoring on Navy Ranges (M3R) project has developed a toolset for passive detection and localization of marine mammals using the existing infrastructure of Navy’s undersea ranges. The Office of Naval Research funded the M3R project as part of the Navy’s effort to determine the effects of acoustic and other emissions on marine mammals and threatened/endangered species. A necessary first step in this effort is the creation of a baseline of behavior, which requires long-term monitoring of marine mammals. Such monitoring, in turn, requires the ability to detect and localize the animals. This paper will present the passive acoustic monitoring and localization tools developed under M3R. It will also present results of the deployment of the M3R tools at the Atlantic Undersea Test and Evaluation Center (AUTEC), Andros Island, Bahamas from June through November 2003. Finally, it will discuss current work to improve automated species classification.
A comparison of model-based and hyperbolic localization techniques as applied to marine mammal calls
Authors: Tiemann Christopher O. , Porter Michael B.
Published: October 2013

A common technique for the passive acoustic localization of singing marine mammals is that of hyperbolic fixing. This technique assumes straight-line, constant wave speed acoustic propagation to associate travel time with range, but in some geometries, these assumptions can lead to localization errors. A new localization algorithm based on acoustic propagation models can account for waveguide and multipath effects, and it has successfully been tested against real acoustic data from three different environments (Hawaii, California, and Bahamas) and three different species (humpback, blue, and sperm whales). Accuracy of the model-based approach has been difficult to verify given the absence of concurrent visual and acoustic observations of the same animal. However, the model-based algorithm was recently exercised against a controlled source of known position broadcasting recorded whale sounds, and location estimates were then compared to hyperbolic techniques and true source position. In geometries where direct acoustic paths exist, both model-based and hyperbolic techniques perform equally well. However, in geometries where bathymetric and refractive effects are important, such as at long range, the model-based approach shows improved accuracy.
A frequency domain blind deconvolution algorithm in acoustics
Authors: Gramann Mark R. , Erling Josh G. , Roan Michael J.
Published: October 2013

It is common in acoustics to measure a signal that has been corrupted by an unknown filtering function during propagation from an unknown source. Blind deconvolution is a technique for learning and applying the inverse of the unknown channel impulse response in order to recover the original source signal. One approach to accomplishing this task is based on an adaptive nonlinear algorithm using mutual information as a cost function [A. J. Bell and T. J. Sejnowski, Neural Comput. 7, 1129–1159 (1995)]. A new frequency domain implementation of this algorithm is presented which greatly reduces computational cost. The frequency domain approach allows adaptive learning rates to be applied individually to each frequency bin of the inverse filter. This technique can lead to improved convergence times for filters with a large spread of frequency response magnitudes. Preliminary results suggest that a factor of two reduction in convergence time and a factor of ten reduction in computational cost can be attained. Experimental results for several simple acoustical systems are presented comparing the performance of the pre-existing time domain algorithm and the new frequency domain implementation. [Work supported by Dr. David Drumheller, ONR Code 333, Contract No. N00014-00-G-0058.]
Simultaneous focal spots obtained at sea using time reversal and reciprocity
Authors: Roux Philippe , Kuperman W. A. , Hodgkiss W. S. , Song Hee Chun , Akal Tuncay , Stevenson Mark
Published: October 2013

Time reversal can be implemented between an array of emitters and an array of receivers by invoking reciprocity in the experimental procedure. The actual process requires connectivity between the two arrays but eliminates the requirement of actually having a probe source. Multiple time reversal focal spots can then be achieved simultaneously in the water column. We verify with data taken in a recent experiment that this streamlined, reciprocity-based procedure yields the same results as the classical method. Of greater importance, it provides a versatile method to study a TRM in a fluctuating medium.
Experimental results of time reversal and optimal inverse filtering performed in a one dimensional waveguide
Authors: Dumuid Pierre M. , Cazzolato Ben S.
Published: October 2013

Time reversal is a common technique for improving the temporal and spatial focusing in the transmission of signals and has been demonstrated in a wide variety of applications. An alternative to time reversal is inverse filtering. Inverse filters are similar to time reversal filters in that they also remove the phase aberations, but they have the added advantage that they also counter the amplitude abberations such that the resulting response through the system has a flat response in the frequency domain. Inverse filtering also provides a means to develop a filter structure that provides a cross-talk cancellation system for multiple input/multiple output systems. In this presentation, results from experimental observations made within a one dimensional waveguide are compared with the commonly used technique of time reversal with an optimal inverse filtering technique. The aim of such experiments is to examine the performance of the time reversal and optimal inverse filtering techniques within a real waveguide and compare these against theoretical predictions. The experiments performed have been developed with a view to extend the research to underwater acoustic communications.
Citadel in Teotihuacan
Authors: Beristain Sergio
Published: October 2013

Teotihuacan, the largest archaeological site nearby Mexico City, is also a place where traditions are maintained through some ceremonies on specific dates, by the Sun and Moon pyramids, and history telling by the pyramids in day to day light and sound shows. This enormous site has a large square in the south known as The Citadel (La Ciudadela), a place some 200×300 meters (m), surrounded by 2.2 m high pyramid basements, and two pyramids to the East (one in front of the main one dedicated to the good Quetzalcoatl). Near the center of this large square sits a 2.2 m basement 18×20 m where some special sound events (theatre, dance, music, etc.) are occasionally presented. Sound level measurements have proved that due to the site conditions, the sound level decreases 3–4 dB on the average per doubling distance, which makes it suitable for large audiences with the only problem of some minor echoes in small portions of the audience area.
Otoacoustic emissions measured in spotted hyenas (Crocuta crocuta)
Authors: McFadden Dennis , Pasanen Edward G. , Weldele Mary L. , Glickman Stephen E. , Place Ned J.
Published: October 2013

From birth, female spotted hyenas exhibit highly masculinized bodies and behaviors. Their external genitalia greatly resemble those of males, and they are behaviorally dominant over males. This marked masculinization raised the question of whether the otoacoustic emissions (OAEs) of female spotted hyenas also would be masculinized. Click-evoked OAEs were measured in six female and six male hyenas at two click levels. Also, distortion-product OAEs were measured at four or more primary levels in three frequency regions: 2, 3.5, and 5.0 kHz. Both CEOAEs and DPOAEs were strong in both sexes in spotted hyenas. In humans, both CEOAEs and DPOAEs are stronger in females than males and stronger in right ears than left. Unlike humans, both the CEOAEs and DPOAEs in female spotted hyenas were weaker than those in males, and unlike humans, OAEs were not stronger in right ears. The implication is that the same androgenizing processes that masculinize the body and behavior of female hyenas also masculinize those elements of the cochlea responsible for OAEs. That implication is being tested by measuring the OAEs of other hyenas in the Berkeley colony that were treated with antiandrogenic agents during fetal development. [Work supported by NIDCD.]
Distortion product otoacoustic emissions provide clues to hearing mechanisms in the frog
Authors: Vassilakis Pantelis , Narins Peter M.
Published: October 2013

Cubic distortion product otoacoustic emissions (DPOAEs) were recorded from 10 Rana pipiens and 10 Rana catesbeiana, 5 males and 5 females each. The I/O curves obtained from the amphibian papilla (AP) of both species are very similar to the respective mammalian curves, indicating that, like in the mammalian cochlea, there may be an amplification process active in the frog AP. The DPOAE level dependence on primary levels is also similar to the mammalian case, suggesting a mechanical structure in the frog inner ear may be functioning analogously to the mammalian basilar membrane. DPOAE audiograms were obtained for primary frequencies spanning the animals hearing range and levels determined by the previous experiments. R. catesbeiana produce stronger emissions than R. pipiens and, consistent with previously reported sexual dimorphism in the mammalian and anuran auditory systems, females from both species produce stronger emissions than males. Additionally, the 2f1−f2 DPOAE is generated primarily at the DPOAE frequency place, while the 2f2−f1 DPOAE is generated primarily at a frequency place between the primaries. This difference in mammalian and frog DPOAEs may be linked to an anatomical difference that results in the acoustic energy following opposite paths through the mammalian and frog inner ears. [Work supported by NIH Grant No. DC-00222 to Peter M. Narins.] a)Currently at De Paul Univ., School of Music, Chicago, IL 60614.
Nonlinear and linear wave equations for propagation in media with frequency power law losses
Authors: Szabo Thomas L.
Published: October 2013

The Burgers, KZK, and Westervelt wave equations used for simulating wave propagation in nonlinear media are based on absorption that has a quadratic dependence on frequency. Unfortunately, most lossy media, such as tissue, follow a more general frequency power law. The authors first research involved measurements of loss and dispersion associated with a modification to Blackstock’s solution to the linear thermoviscous wave equation [J. Acoust. Soc. Am. 41, 1312 (1967)]. A second paper by Blackstock [J. Acoust. Soc. Am. 77, 2050 (1985)] showed the loss term in the Burgers equation for plane waves could be modified for other known instances of loss. The authors’ work eventually led to comprehensive time-domain convolutional operators that accounted for both dispersion and general frequency power law absorption [Szabo, J. Acoust. Soc. Am. 96, 491 (1994)]. Versions of appropriate loss terms were developed to extend the standard three nonlinear wave equations to these more general losses. Extensive experimental data has verified the predicted phase velocity dispersion for different power exponents for the linear case. Other groups are now working on methods suitable for solving wave equations numerically for these types of loss directly in the time domain for both linear and nonlinear media.
Are the energy analysis (EA) and the statistical energy analysis (SEA) compatible?
Authors: Maidanik G. , Becker K. J.
Published: October 2013

The statistical energy analysis (SEA) is being used commercially to find ways of achieving noise control on vehicles of various types. A tenet of SEA states that the modal energy stored in a force-driven (master) dynamic system may not exceed the modal energy stored in a passive (adjunct) dynamic system to which it is coupled. Some recent computations using an energy analysis (EA) of generic coupled dynamic systems shows that this rule may not be obeyed in (EA). To render (EA) compatible with (SEA) a lower limit on the value of the modal overlap parameter in the adjunct dynamic system must be imposed. The value must exceed a threshold for these two analyses to be compatible. [Work supported by ONR.]
Landmine vibration modes
Authors: Donskoy Dimitri , Zagrai Andrei , Ekimov Alexander
Published: October 2013

Recent experimental and theoretical studies in the field of seismo-acoustic landmine detection proved high potential of this technique. Investigations have also demonstrated that acoustic detection and discrimination of landmines is a complex problem dependent upon interaction between soil and buried mines and their respective properties. Vibration characteristics of a mines casing play a critical role in this problem. Our recent tests, for the first time, revealed the multi-modal vibrations of mines. It was observed that the resonance frequencies of the soil/mine system depend on the burial depth and soil conditions. The present study provides analysis of this phenomenon both experimentally and though physical modeling. The experimental investigations were focused on the effects of burial depth and soil moisture content on vibration response measured on the soil surface above the buried mine. The modeling efforts were based on the electro-mechanical analogy approach where each vibration mode was represented as an oscillator with its own effective parameters. The validity of this consideration was confirmed through comparison against conventional modal analysis approach. The study demonstrated good agreement between the developed model and experimental results.
Fundamentals of spoken word recognition
Authors: Luce Paul A. , McLennan Conor
Published: October 2013

Researchers have made significant progress in identifying the basic principles responsible for the normal-listener’s rapid and accurate identification of spoken words. In particular, there is now almost uniform consensus that spoken word recognition involves two fundamental processes: activation and competition. Most current models of recognition propose that stimulus input (i.e., a spoken word) activates a set of representations of similar sounding words in memory that subsequently vie for recognition. Despite the fact that similarity is afforded a crucial role in activating and discriminating among lexical competitors, we currently have little precise information regarding perceived similarity relations among spoken words. We will discuss the fundamental role of similarity in current models of spoken word recognition, past attempts to capture perceived similarity among spoken words, and ongoing efforts in our laboratory to understand more deeply the precise role of similarity in the perception of spoken stimuli. [Work supported by NIH.]
Two perspectives on similarity between words
Authors: Frisch Stefan A.
Published: October 2013

This presentation examines the similarity between words from both bottom up (phonetic) and top down (phonological/psycholinguistic) perspectives. From the phonological perspective, the influence of structure on similarity is explored using metalinguistic acceptability judgments for multisyllabic nonwords. Results from an experiment suggest that subjects try to align novel words with known words in order to maximize similarities while minimizing dissimilarities. This finding parallels results from psychology on similarity judgments for visual scenes. From the phonetic perspective, the influence of similar gestures on speech error rates is examined using ultrasound measurement of tongue position. In a pilot experiment, subjects, produced tongue twisters containing words where onset and vowel phonemes had similar gestures (e.g., tip, comb) and where the onset and vowel had dissimilar gestures (e.g., tube, keep). Preliminary results suggest that misarticulations are more frequent in the context of dissimilar gestures (e.g., in the tongue twister tip cape keep tape, error rates are higher for /k/ than /t/). These errors appear to be gestural interactions rather than errors at the phonemic or featural level of phonological spellout. Together, these two experiments indicate that similarity relations between words are found at multiple levels, any which are potentially relevant to the structure of phonological systems.
The development of sensitivity to speech sound dissimilarity in humans
Authors: Ponton Curtis
Published: October 2013

The understanding of spoken language development has been expanded by examining speech-sound evoked brain activity recorded using an oddball presentation paradigm. When brain activity is recorded using this paradigm, a response known as the mismatch negativity (MMN) is generated. The MMN is regarded as a neurophysiological correlate of short-term auditory memory processes that are necessary for behavioral discrimination. Numerous investigations have demonstrated that neural generators underlying the MMN are sensitive to a wide range of acoustic contrasts, including both nonspeech and speech sounds. Recent studies have shown that for at least some speech sound contrasts, the MMN is present at birth and is insensitive to native/non-native speech contrasts. The appearance of language-specific contrasts around six months of age appears to correspond with the emergence of myelinated connections between the thalamus and auditory cortex. Combined, the neurophysiological and anatomical data suggest that this neural mechanism for detecting dissimilarity may have subcortical or cortical loci, depending on the speech contrast. Particularly for vowels, this dissimilarity processing may be the basis for developing categorization.
The importance of duration in the perception of glides and vowels
Authors: Coren Amy E. , Warren Willis J.
Published: October 2013

The segmental duration for the perception of glides versus vowels was investigated. A central Texas Spanish speaker produced a single token of radio with a high vowel duration of 150 ms. The duration of the high vowel, [i], was edited at the midpoint in 10-s intervals to see at what length listeners perceive a complete vowel versus a glide, i.e., radyo versus radio. Ten listeners judged ten repitions of the ten tokens. It was determined that the steady state of the vowel must retain somewhere near 80 ms to be perceived as a full vowel.
The impact of phonetic dissimilarity on the perception of foreign accented speech
Authors: Weil Shawn A.
Published: October 2013

Non-normative speech (i.e., synthetic speech, pathological speech, foreign accented speech) is more difficult to process for native listeners than is normative speech. Does perceptual dissimilarity affect only intelligibility, or are there other costs to processing? The current series of experiments investigates both the intelligibility and time course of foreign accented speech (FAS) perception. Native English listeners heard single English words spoken by both native English speakers and non-native speakers (Mandarin or Russian). Words were chosen based on the similarity between the phonetic inventories of the respective languages. Three experimental designs were used: a cross-modal matching task, a word repetition (shadowing) task, and two subjective ratings tasks which measured impressions of accentedness and effortfulness. The results replicate previous investigations that have found that FAS significantly lowers word intelligibility. Furthermore, in FAS as well as perceptual effort, in the word repetition task, correct responses are slower to accented words than to nonaccented words. An analysis indicates that both intelligibility and reaction time are, in part, functions of the similarity between the talker’s utterance and the listener’s representation of the word.
Automatic computational models of acoustical category features: Talking versus singing
Authors: Gerhard David
Published: October 2013

The automatic discrimination between acoustical categories has been an increasingly interesting problem in the fields of computer listening, multimedia databases, and music information retrieval. A system is presented which automatically generates classification models, given a set of destination classes and a set of a priori labeled acoustic events. Computational models are created using comparative probability density estimations. For the specific example presented, the destination classes are talking and singing. Individual feature models are evaluated using two measures: The Kologorov–Smirnov distance measures feature separation, and accuracy is measured using absolute and relative metrics. The system automatically segments the event set into a user-defined number (n) of development subsets, and runs a development cycle for each set, generating n separate systems, each of which is evaluated using the above metrics to improve overall system accuracy and to reduce inherent data skew from any one development subset. Multiple features for the same acoustical categories are then compared for underlying feature overlap using cross-correlation. Advantages of automated computational models include improved system development and testing, shortened development cycle, and automation of common system evaluation tasks. Numerical results are presented relating to the talking/singing classification problem.
Acoustic intensity in the interaction region of a parametric source
Authors: Lauchle G. C. , Gabrielson T. B. , Van Tol D. J. , Kottke N. F. , McConnell J. A.
Published: October 2013

The goal of this project was to measure acoustic intensity in the strong interaction region of a parametric source in order to obtain a clear definition of the source-generation region and to separate the local generation (the reactive field) from propagation (the real or active field). The acoustic intensity vector was mapped in the interaction region of a parametric projector at Lake Seneca. The source was driven with primary signals at 22 kHz and 27 kHz. Receiving sensors were located 8.5 meters from the projector. At that range, the secondary at 5 kHz was between 40 and 45 dB below either primary. For the primary levels used, the plane-wave shock inception distance would have been at least 14 meters. Furthermore, the Rayleigh distance for the projector was about 4 meters so the measurements at 8.5 meters were in the strong interaction region but not in saturation. Absorption was negligible over these ranges. The intensity measurements were made at fixed range but varying azimuth angle and varying depth thus developing a two-dimensional cross-section of the secondary beam. Measurements of both the active and reactive intensity vectors will be presented along with a discussion of measurement error. [Work supported by ONR Code 321SS.]
Cardioid processsing of reverberation data observed on the STRATAFORM with the Five Octave Research Array (FORA)
Authors: Preston John R.
Published: October 2013

The author recently participated in ONR’s 2003 Geoclutter Experiment to study shallow water bottom reverberation and clutter in the STRATAFORM off New Jersey. The experimental effort was lead by M.I.T. and included researchers from the Naval Research Laboratory, Penn State Univ., and the Naval Underwater Weapons Center. Sources were bistatic coherent pulses from 400 to 3600 Hz. The receiver was the new Five Octave Research Array (FORA). The STRATAFORM is known to have benign surface morphology but contains many buried river channels and other sub-surface horizons. Some highlights of the reverberant returns are discussed that include the correlation of returns with a bottom mounted target and probable fish schools. The main objective of this work is to assess the directional characterization of the observed clutter. The cardioid aperture of FORA should, in theory, yield good estimates of the sources of reverberation above ∼1800 Hz. Examples from the rverberation data analysis are presented using a cardioid beamforming algorithm developed by SACLANTCEN. [Work supported by ONR Code 32, Grant N00014-03-1-0113.]
Ocean acoustic wave propagation and ray method correspondence: Internal wave fine structure
Authors: Cerruti Nicholas R. , Hegewisch Katherine C. , Tomsovic Steven
Published: October 2013

Acoustical wave fields can only detect structures in the ocean’s sound-speed fluctuations that are on the order of the smallest acoustic wavelength component. On the other hand, geometrical ray-tracing methods are sensitive to infinitely fine structures in the wave modeling of these fluctuations. Hence, a proper model seeking agreement between ray methods and wave propagation must, at a minimum, filter out the fine oscillations of the internal wave field. Starting from an efficient numerical scheme for generating the internal waves introduced by Brown and Colosi [J. Acoust. Soc. Am. 103, 2232 (1998)], which reproduces the Garrett–Munk spectrum, we introduce a smoothing technique that removes the unphysical portion of the internal wave modeling. The key is to find a smoothing that does not significantly alter the propagated wave field, yet eliminates as much of the ‘‘micro-folding’’ phenomena that was discussed by Simmen et al. [J. Acoust. Soc. Am. 102, 239 (1997)]. We give a characterization of the extent of smoothing necessary as a function of acoustic frequency and propagation range, and show how it improves the correspondence. Finally, we note that the smoothing allows detailed ray methods to be implemented further in range. [Work supported by ONR.]
Scattering in a 3-D wedge with a rough bottom boundary
Authors: Knobles D. P.
Published: October 2013

Scattering problems in ocean waveguides may be formulated in the context of a set of coupled inhomogeneous integral equations. A particular problem of interest is the physics of low frequency reverberation in an ocean waveguide with a bottom described by a rough interface superimposed on a sloped boundary that defines the water–sediment interface. An idealization of such a waveguide is a 3-D wedge with a rough bottom. The Helmholtz equation for the propagation of sound for such an environment is examined by solving the basic coupled integral equations. Reverberation time series for a bistatic source–receiver geometry are computed by Fourier synthesis of the frequency response of the sum of the direct, refracted, and scattered components of the acoustic field. An objective of the computations is to examine the interplay between the refracted component of the field that results from the wedge geometry and the scattering components that result from the rough bottom. Although this picture of reverberation is incomplete since the physics of volume scattering is ignored, it allows one to examine the basic physics of reverberation in a waveguide that has variations in both range and azimuth. [Work supported by ONR.]
Recent developments in underwater acoustic modeling
Authors: Etter Paul C.
Published: October 2013

This is the fourth paper in an ongoing series of research reviews presented at eight-year intervals [P. C. Etter and R. S. Flum, J. Acoust. Soc. Am. Suppl. 1 65, S42 (1979); P. C. Etter, ibid. 82, S102 (1987); J. Acoust. Soc. Am. 97, 3312 (1995)]. This review of international developments in underwater acoustic modeling reveals an inventory containing 114 propagation models, 17 noise models, 17 reverberation models and 26 sonar performance models representing a 38% increase over the 1995 inventory. As in previous reviews, older models have been retained to provide an historical perspective that enables researchers to pose well-informed questions regarding the need for future developments. When executed in higher-level simulations, these models generate predictive and diagnostic outputs that are useful to sonar technologists or acoustical oceanographers in the analysis of complex systems operating in the undersea environment. Recent applications of underwater acoustic models in naval operations, offshore industries and oceanographic research will be discussed. This review coincides with the appearance of the third edition of Underwater Acoustic Modeling and Simulation (Spon Press, London, 2003), which provides a detailed account of research conducted over the past four decades.
Acoustical design issues in justice facilities
Authors: Pelton Howard K. , Carnes Ted N.
Published: October 2013

This paper presents various acoustical design challenges experienced by the authors with regard to courtrooms and jail facilities. The challenges in courtrooms include avoiding the sound focusing tendencies of concave curved surfaces and the general preference by courtroom designers for hard (i.e., sound reflecting) surface material. Jail facilities have attempted in recent years to incorporate sound absorbing surfaces to reduce noise, but this is difficult to achieve with durable materials that also must meet the security requirements of such facilities. Another interesting challenge is mitigating the intrusive noise of industrial grade toilets flushing when they are located in holding tanks adjacent to courtrooms.