bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of burst parameters on automotive brake squeal suppression
Authors: Badertscher Jeff , Cunefare Kenneth A.
Published: October 2013

Implementing a dither control signal with a 100% duty cycle is an effective means of suppressing automotive brake squeal. Dither control is a method by which high-frequency control efforts are introduced into a system to suppress a lower frequency disturbance. Dither is introduced to a brake by placing a piezoelectric stack actuator in the piston of a floating caliper brake. Burst mode dither control is characterized by duty cycles of less than 100%. A burst control signal of a specific duty cycle is also specified by the burst count and burst rate. Burst mode signals are shown to suppress brake squeal. This paper examines the nature of suppression and the effectiveness of burst mode dither control signals with varied burst parameters. An examination of the squeal response and dither control signal is used to examine the nature of suppression during bursting and dwell time. The amplitude of the control signal that is necessary to obtain full control of the system is used to assess control signal effectiveness.
Modeling the effect of bearing properties on the eigenvalues of a rotordynamic system
Authors: Wagner Ben B. , Ginsberg Jerry H.
Published: October 2013

Experimental data indicate that changes in bearing properties alter the natural frequency and damping ratios of rotordynamic systems [R. M. Baldwin, ASME 92-GT-53]. The work presented here examines the development of a mathematical model that will be used to investigate how natural frequency, modal damping ratio, shaft rotation rate, bearing clearance, and lubricant viscosity are related. The modeled system consists of a uniform, elastic, rotating shaft, which is supported by two plain journal bearings, and a single, rigid disk, which is concentrically welded to the shaft away from midspan. Standard lubrication theory is used to generate the stiffness and damping matrices for the bearings. A Ritz series expansion is used to generate the mass, shaft stiffness, and gyroscopic matrices describing the shaft and disk. The combined action of the bearings and shaft/disk system is described by matrices representing the effects of stationary and rotational inertia, stiffness, and internal and external damping. The radial clearance and lubricant viscosity are independently adjustable at each bearing, and the range of shaft speed for analysis is user-specified. A nonsymmetric generalized eigenvalue problem solver is used to calculate eigenvalues, whose real part is proportional to the modal damping ratio, and whose imaginary part is the natural frequency. For Structural Acoustics and Vibrations Best Student Paper Award. Submitted for Structural Acoustics and Vibrations Young Presenter Award.
Active noise control using damped resonant filters
Authors: Bisnette Jesse B. , Vipperman Jeffrey S. , Budny Daniel D.
Published: October 2013

Active Noise Control (ANC) has been found to work well at low frequencies, thereby complementing passive noise control techniques. There are two distinct topologies for ANC: feedforward and feedback. Feedforward implementations work through the superposition of a primary and secondary sound field while feedback systems work by augmenting the dynamics of an enclosed sound field to add damping. Model-based feedback control systems are cumbersome to implement due to typical high modal density and simple output feedback systems are complicated for two reasons. First, perfectly collocated sensor (microphone) and actuator (loudspeaker) pairs are difficult to achieve, and second, the dynamics of the loudspeaker are destabilizing. Lane and Clark (1998) have reported compensating loudspeaker dynamics over a bandwidth to produce an approximate volume velocity source and demonstrated rate feedback acoustic control. Here, an acoustic control method using second order filters, which is analogous to positive position feedback (PPF) control in structural systems, is presented. The phase response of the loudspeaker is accounted for by incorporating negative feedback with either band-pass or high-pass filters, and the technique appears to have the same tolerance for actuator dynamics as for the structural case. Alternatively, the approximate volume velocity source could also be used.
When things go crunch: Gap length effects on a magnetorheological tunable vibration absorber
Authors: Albanese Anne-Marie , Cunefare Kenneth
Published: October 2013

A tunable vibration absorber (TVA), where the tunable element is a magneto-rheological (MR) elastomer spring, has demonstrated up to a 460% change on tuning frequency. A frequency increase is associated with a significant decrease in the springs static equilibrium length, referred hereto as a crunch. The crunch is caused by magnetic attractive forces across the spring. The spring, an iron-doped silicone gel, is placed between two halves of a low-carbon steel loop. One loop half behaves as an absorber mass, and has approximately 200 turns of magnet wire around it. Driving current through this wire generates a magnetic flux around the steel path and through the MR spring. Beyond a threshold, the magnetic field induces a large frequency shift in the absorber, with a crunch observed across the elastomer. The crunch can occur when the static equilibrium length is unconstrained by geometry, thus a magnetic attractive force shortens the spring length. The relationship between the magnitude of the crunch and the frequency shift will be presented. Additionally, the impact of different initial MR spring lengths on the frequency behavior will be considered. Finally, the frequency variability achievable by MR-spring-based TVAs with and without the crunch will be assessed.
Some components of the ‘‘cocktail-party effect,’’ as revealed when it fails
Authors: Divenyi Pierre L. , Gygi Brian
Published: October 2013

The precise way listeners cope with cocktail-party situations, i.e., understand speech in the midst of other, simultaneously ongoing conversations, has by-and-large remained a puzzle, despite research committed to studying the problem over the past half century. In contrast, it is widely acknowledged that the cocktail-party effect (CPE) deteriorates in aging. Our investigations during the last decade have assessed the deterioration of the CPE in elderly listeners and attempted to uncover specific auditory tasks, on which the performance of the same listeners will also exhibit a deficit. Correlated performance on CPE and such auditory tasks arguably signify that the tasks in question are necessary for perceptual segregation of the target speech and the background babble. We will present results on three tasks correlated with CPE performance. All three tasks require temporal processing-based perceptual segregation of specific non-speech stimuli (amplitude- and/or frequency-modulated sinusoidal complexes): discrimination of formant transition patterns, segregation of streams with different syllabic rhythms, and selective attention to AM or FM features in the designated stream. [Work supported by a grant from the National Institute on Aging and by the V.A. Medical Research.]
Machine recognition of sounds in mixtures
Authors: Ellis Daniel , Barker Jon
Published: October 2013

A machine simulation of human auditory perception must be able to recognize and classify individual sound sources. The most successful technique for sound classification is the statistical pattern recognition approach employed in speech recognizers; however, in most practical cases, this approach assumes that the entire (monaural) signal represents the source to be classified. Realistic ‘‘cocktail-party’’ scenes, composed of multiple, overlapping sources with comparable energies, do not come close to meeting this assumption. A more workable assumption is to treat each time-frequency cell as representing a single source, and to use missing-data techniques to perform recognition using only a subset of the cells. This precludes the use of cepstral features (which depend on every frequency component), but is otherwise practical. The problem then becomes finding the ‘‘present data mask’’ that indicates which cells are to be considered during classification of a particular source. We will present a system based on these principles, with applications both to speech recognition in dynamic, noisy backgrounds, and also to nonspeech sounds such as alarms that can occur at very poor signal-to-noise ratios.
How is harmonicity used in grouping speech sounds?
Authors: Darwin Chris
Published: October 2013

This paper asks how a common property of voiced speech sounds harmonicity is used by the auditory system to improve the perception of speech in the presence of simultaneous competing sounds. We present data from three different experimental paradigms concerned, respectively, with the combination of sounds across different ears, different frequency regions, and different times. The first set of experiments qualify the conclusion that sounds from the same harmonic series fuse into a single object when presented to different ears. The second impose limits on the ability of harmonicity to combine information across different frequency regions. The third demonstrate the utility of continuity of pitch (compared with a vocal-tract size) in maintaining attention to a single sound source. Elucidating the mechanisms by which we segregate speech from background sounds requires proper consideration both of the structure of the speech signal and of the auditory system through which it passes.
Scene analysis without spectral analysis?
Authors: de Cheveigne Alain
Published: October 2013

Auditory scene analysis is often described in terms of grouping stimulus components. Components, once grouped, are assigned to one source or another [A. S. Bregman, Auditory Scene Analysis (MIT, Cambridge, MA, 2002)]. The actual grouping must operate on whatever representation is available within the auditory nervous system. An obvious hypothesis is that correlates of individual stimulus components are created by peripheral spectral analysis. However, peripheral frequency resolution is limited. The number of resolved partials is between 5 and 8 for a harmonic complex in isolation, but resolution must necessarily be less good for the interleaved components of concurrent sources. Source amplitudes are rarely equal, and partials of a weaker source must be particularly hard to resolve. The question is thus: given the paucity of resolved elements to group, how does the auditory system perform the grouping? A number of possibilities will be reviewed. One is that partials not resolved peripherally are somehow resolved centrally (a modern version of the ‘‘second filter’’ hypothesis). Another is that scene analysis does not operate by grouping resolved elements, but instead by modifying directly unresolved entities, for example by time-domain processing.
A model subspace method for matched field source localization in a shallow-water acoustic waveguide
Authors: Daly Peter M.
Published: October 2013

Model subspace methods for parameter estimation can yield promising results when temporal or spatial variability dominate the model inputs. Application of Gaussian signal detection theory, summarized by Van Trees, is applied to the localization problem. Model inputs, such as the sound velocity profile in water, bottom properties, and array position, rather than being deterministic, are characterized using a Gaussian random vector. This, in turn, yields a random signal model which is represented as a vector space. Detection and localization via a maximum-likelihood estimator becomes a question of whether the received signal fits the subspace defined by the random signal model.
High-frequency acoustic scattering from gas-bearing zooplankton
Authors: Lavery Andone C. , Stanton Timothy K. , Wiebe Peter H. , Benfield Mark C. , Greene Charles H.
Published: October 2013

High-frequency acoustic scattering is well-suited to the synoptic investigation of marine organisms that inhabit the water-column, such as zooplankton and fish. However, the scattering characteristics of the organisms can be highly complex, and one must look for ways to distinguish one type of organism from another when interpreting the received echoes. From an acoustic scattering perspective, zooplankton generally fall into one of three categories: gas-bearing, fluid-like, or elastic-shelled. Scattering models, of different levels of sophistication are available for all three types of zooplankton. Gas-bearing zooplankton, unlike the other zooplankton categories, have a strong scattering resonance, which can be exploited for their identification. Scattering from gas-bearing zooplankton at frequencies close to the resonance frequency is much stronger than scattering from other zooplankton. Thus, in this frequency region, acoustic scatter from a small number of gas-bearing zooplankton can overwhelm that from a far larger number of fluid-like or elastic-shelled zooplankton. A series of zooplankton surveys of the Gulf of Maine has recently been completed in which a multi-frequency towed instrument platform, BIOMAPER-II, was employed. The strong scattering resonance of gas-bearing zooplankton, together with scattering models and ground-truthing, was exploited in order to determine regions with high densities of gas-bearing zooplankton.
Potential effect of resonant scattering from multiple swimbladders on audition in juvenile fish
Authors: Hastings Mardi C.
Published: October 2013

The swimbladder, a gas-filled chamber in the abdominal cavity of most bony fishes, is a hydrostatic organ that enables fish to maintain neutral buoyancy; however, it also responds to acoustic pressure and radiates a secondary acoustic field that enhances detection capability of the inner ear. Recent experiments have indicated that resonant response of the swimbladder may control the auditory bandwidth in at least four species of fish [Hastings et al., J. Acoust. Soc. Am. 110, 2640 (2001)]. The auditory bandwidths of these fishes, however, do not change appreciably while they grow even though the resonance frequency of the swimbladder decreases with increasing body length. Results of an analysis inspired by Feiullade et al. [J. Acoust. Soc. Am. 112, 2206 (2002)] show that the downward shift and broadening associated with resonance of the aggregate scattered field from multiple fish is perhaps sufficient enough to account for this discrepancy. Effects of resonant characteristics of a single swimbladder, fish length, and number of fish on the changes in the collective scattered field are presented. Thus the resonant scattered field created by relatively large schools of juvenile fish may enhance their auditory capability.
Vibro-acoustography: The sound of tissue
Authors: Greenleaf James , Fatemi Mostafa
Published: October 2013

Palpation is routinely used for detecting pathology using the stiffness of the tissue and is more than 2000 years old. Palpation is subjective and limited to individual experience and to the accessibility of the tissue region to touch. Noninvasive images of elastic modulus may be useful to distinguish tissues and pathologic processes based on mechanical properties such as elastic modulus. Static, quasistatic, or cyclic stresses have been applied while strains have been measured using ultrasound or MRI. The related elastic modulus has been estimated from visco-elastic models of tissue mechanics. Recently we have developed a new ultrasound technique that produces speckle free images related to both tissue stiffness and reflectivity. This method, termed Ultrasound Stimulated Vibro-acoustography [Science 280, 83–85 (1998); PNAS 96, 6603–6608 (1999)], uses ultrasound radiation pressure to produce sound vibrations from a small region of the tissue that depend on the scattering and elastic characteristics of the tissue. The method can detect microcalcification within breasts, and promises to provide high-quality images of calcification within the arteries. Vibro-acoustography can detect mechanical defects in prostheses such as artificial mitral and aortic valves. The method may also be used in nondestructive evaluation. [Work supported by HL 61451, DBI 7980-4.]
A new imaging technique based on resonance for arterial vessels
Authors: Zhang Xiaoming , Fatemi Mostafa , Greenleaf James F.
Published: October 2013

Vibro-acoustography is a new noncontact imaging method based on the radiation force of ultrasound. We extend this technique for imaging of arterial vessels based on vibration resonance. The arterial vessel is excited remotely by ultrasound at a resonant frequency, at which the vibration of the vessel as well as its transmission to the body surface are large enough to be measured. By scanning the ultrasound beam across the vessel plane and measuring the vibration at one single point on the body or vessel surface, an image of the interior artery can be mapped. Theory is developed that predicts the measured velocity is proportional to the value of the mode shape at resonance. Experimental studies were carried out on a silicone tube embedded in a cylindrical gel phantom of large radius, which simulates a large artery and the surrounding body. The fundamental frequency was measured at which the ultrasound transducer scanned across the tube plane with velocity measurement at one single point on the tube or on the phantom by laser. The images obtained show clearly the interior tube and the modal shape of the tube. The present technique offers a new imaging method for arterial vessels.
The singing voice and country music
Authors: LeBorgne Wendy D.
Published: October 2013

Preliminary acoustic measures on the Broadway Belt voice suggest uniqueness in this type of vocal production. This study objectively compared the acoustic production of the Broadway Belt voice in four elite and four average belters. Three casting directors evaluated the vocal quality of 20 musical theater majors proficient in the singing style referred to as belting. Each belter sang two specified vocalizes as well as six short excerpts from the belting repertoire. The raters judged the belters on a set of seven perceptual parameters (loudness, vibrato, ring, timbre, focus, nasality, and registration breaks) and reported an overall score. Initially, Pearson product-moment correlation coefficients were calculated and reported for perceived loudness, vibrato, ring, timbre, focus, and nasality for the elite and average groups. Then, significant acoustic results related to vocal intensity, amplitude and magnitude of vibrato, increased spectral energy in the expected Singer’s Formant area, and trends in F1–F2 characteristics were assessed. Overall patterns of these results suggest the elite belters maintained a greater magnitude of vocal vibrato, a brighter vocal quality on some vowels, and different harmonic−−formant relationships than average belters. Specific relevant data related to these acoustical events will be the focus of this presentation.
Characterization of highway traffic noise generated by rigid pavement contraction joints
Authors: Ellis Lawrin T. , Niezrecki Christopher , Bloomquist David
Published: October 2013

Contraction joints in rigid (concrete) pavements are required to permit expansion of each monolithic section of roadway. At higher speeds, the major source of highway noise is attributed to vehicle tire/roadway interaction. Current concerns about limiting the impact of highway traffic noise has forced transportation agencies to consider strategies to control noise generated by tire/roadway interaction. Within this work the difference in noise generated by 1/4- vs 3/8-in. joint widths is conducted. The study focuses on passenger vehicles including a sedan and a light duty van/truck. Both vehicle in-cabin and roadside noise levels are measured for vehicle speeds of 50, 60, and 70 miles per hour. For the sedan, the minimum and maximum observed in-cabin differences were determined to be 1.08 and 1.82 dB(A), respectively. Minimum and maximum observed roadside differences are 1.19 and 2.58 dB(A), respectively. Van tests resulted in minimum and maximum observed in-cabin differences of 0.60 and 1.09 dB(A) and minimum and maximum observed roadside differences of 1.05 and 3.18 dB(A), respectively. This paper contains details of reference standards, test methods, and the results obtained.
A new approach to control noise from entertainment facilities: Active control and measurement of amplified community noise
Authors: Peppin Richard J. , Casamajó Joan
Published: October 2013

While traffic noise is perhaps the most pervasive of community noises, much of the contribution now comes from amplified sound: live music, discos, theme parks, and exercise studios. Those producing the sound or music want it loud and those not interested want to be protected against noise. Noise limits at the receiving or producing property line must be met for the minimum community acceptance. However the time-, and perhaps the spatially-, varying sound in entertainment facilities is often constantly modified (and maybe monitored) near the source of the sound. Hence it is hard to relate and to control the sound at the property line. This paper presents a unique noise control device. It is based on the octave band ‘‘transfer function’’ between the sound produced in the entertainment area and the noise received at the property line. The overall insulation can be measured and is input to the instrument. When a noise level limit is exceeded at the receiver, due to the amplified interior noise at the facility, the sound output of the device is automatically controlled to reduce the noise. The paper provides details of the design and possible abatement scenarios with examples.
Recent progress with atmospheric noise-reducing filters
Authors: Hedlin Michael
Published: October 2013

Wind noise is one of the key issues facing the community of acousticians who monitor the atmosphere for long-period signals from natural atmospheric phenomena or from man-made sources, such as nuclear weapons tests. Presently, a network of infrasound observing sites is being constructed to provide global coverage of acoustic sources in the atmosphere. It is well known that spatial filters can be used to attenuate noise due to atmospheric turbulence near the recording point and increase the ratio of signal-to-noise. Rosette spatial filters are currently used at the new infrasound monitoring stations and have been found to provide a significant reduction of noise across the frequency band of interest to the acoustic monitoring community. Research continues into modifications to existing rosette filters that might improve their performance. Additional research is providing insight into entirely different filters, such as wind barriers. Some of the monitoring systems array sites are located on oceanic islands at locations where spatially extensive noise filters will not be practical. This practical limitation fuels our interest in effective, spatially compact filtering methods. This presentation gives an overview of the various filters currently being used and research into improvements for these filters and into entirely different filter designs.
Understanding cochlear function through auditory-nerve activity: A Zwislocki perspective
Authors: Schmiedt Richard A.
Published: October 2013

Dr. Joe Zwislocki served as my dissertation advisor during those tumultuous years in cochlear physiology when our understanding of outer hair cell (OHC) function was evolving from that of a sensory cell to that of a mechanical amplifier. Spoendlin had recently demonstrated that 90%–95% of auditory-nerve afferents originated from inner hair cells (IHCs), but the characteristics of IHC receptor potentials remained an enigma. Otoacoustic emissions and OHC electromotility were terms yet to be defined. Theories relating auditory-nerve activity to basilar-membrane mechanics included concepts of second filters, basilar-membrane nonlinearities, and phase opposition. It was a fertile time for theories and experiments attempting to describe a black-box system that did not yield its mysteries easily. Around 1977, IHC receptor potentials were found to be as sharply tuned as auditory-nerve responses, and the era of cochlear micromechanics began. Joe Zwislocki, as usual, has played a primary role in defining this new era, utilizing the relationships between the OHC stereocilia and the tectorial membrane as his modeling clay.
A comparison of Levitt and Zwislocki decision rules for use with forced-choice adaptive procedures
Authors: Schlauch Robert S. , Carney Edward J.
Published: October 2013

Forced-choice adaptive procedures enjoy widespread use for the measurement of detection and discrimination thresholds. Zwislocki et al. [J. Acoust. Soc. Am. 30, 254–262 (1958)] proposed an adaptive procedure with a decision rule that targets 75% correct several years before these procedures gained acceptance in psychophysics, and even today little is known about the statistical properties of this decision rule. This paper evaluates, using computer simulations, the bias and efficiency of Zwislocki’s proposed decision rule in 2-alternative forced-choice (AFC) and 3-AFC procedures under conditions of full attention and inattenion. The results for this decision rule compare favorably with two popular rules proposed by Levitt [J. Acoust. Soc. Am. 49, 467–477 (1971)] that target 70.7% correct and 79.4% correct. In summary, the rule that targets 75% correct (Zwislocki’s rule) produces less biased threshold estimates than the rule that targets 70.7% correct and it is affected less by inattention than the rule that targets 79.4% correct. This research supports the addition of Zwislocki’s rule to the psychophysical toolbox.
Active control of payload fairing noise using distributed active vibration absorbers
Authors: Charpentier Arnaud , Johnson Marty E. , Fuller Chris R.
Published: October 2013

High sound pressure inside a launch vehicle fairing during lift-off can damage the payload. Interior levels of up to 140 dB between 60 and 250 Hz are mostly due to exhaust plume noise combined with the limited transmission loss of lightweight composite fairings and little acoustic damping in the fairing volume. Past work using passive and hybrid passive/reactive noise control devices has shown that their limitations are mostly due to packaging volume and weight penalty. The objective of this work is to design a lightweight, compact, and low electrical power active noise control system to reduce the fairing interior sound level. Hybrid active/passive actuators such as Smart Foam (Couche and Fuller, Proceedings of Active 1999, Ft. Lauderdale, FL, pp. 609–620) and Distributed Active Vibration Absorbers (Marcotte, Fuller, and Johnson, Proceedings of Active 2002, ISVR, Southampton, England, pp. 535–546) are optimized for fairing noise control. The latter have been used to increase the transmission loss of the fairing. Active noise control test results on a sub-scale, sandwich composite fairing are presented. The global interior acoustic response due to airborne exterior excitation is minimized using an adaptive multiple-input, multiple-output feedforward controller. [Work supported by the Air Force Research Laboratory, Space Vehicles Directorate (AFRL).]
Hybrid NAH formulations for an arbitrary object in a nonfree field
Authors: Wu Sean
Published: October 2013

Previous nearfield acoustical holography (NAH) formulations based on the Helmholtz integral theory and boundary element method (BEM) are effective for an arbitrary object in a free field, although a true free field is nonexistent. While a modified Helmholtz equation least squares (HELS) method using expansions of both outgoing and incoming spherical waves can provide an approximate solution for such a scenario [Wu and Zhao, J. Acoust. Soc. Am. 111, 2409 (2002)], the reconstruction accuracy may be unsatisfactory when the source is of arbitrary geometry. In this paper, a hybrid NAH formulation that combines a modified HELS method, the Helmholtz integral theory, BEM, and regularization techniques (e.g., modified Tikhonov regularization, generalized cross validation) is developed for reconstructing acoustic radiation from an arbitrary object in a nonfree field. This hybrid formulation has the advantages of the modified HELS method and BEM-based NAH, and represents a significant improvement over the combined HELS method [Wu and Zhao, J. Acoust. Soc. Am. 112, 179–188 (2002)]. The input data are collected on a conformal surface at close range, so the evanescent waves can be captured and the reconstruction accuracy can be improved. Moreover, the majority of the input data are calculated but not measured, and the reconstruction efficiency is enhanced. [Work supported by NSF.]
Cocktail party effect in infants: Visual information and speech segmentation in noise
Authors: Hollich George
Published: October 2013

What are infants abilities to use what they see to segment speech in a noisy environment? Infants often find themselves in situations far louder and more complex than the acoustic isolation chambers of traditional infant testing. The current series of studies used the headturn preference procedure (with video familiarization) to examine 7.5-month-old infants abilities to use visual/auditory correlations to reliably attend to and segment a given speech stream in the face of a distracting voice. Results indicated that in contrast to seeing a static face, infants succeeded at segmentation when a dynamic visual display of the face of the talker matched the acoustic passage. That is, when two blended voices were of equal loudness, infants could use visual correspondences to reliably recognize words presented in the matching video. Furthermore, they did so even if the video display was changed to a synchronized oscilloscope pattern, rather than a face. They also succeeded when the video display was simply a synchronized flashing light. These results suggest that this ability is related to domain-general sensitivities for intermodal correspondences, rather than any face-specific effects, and suggest a mechanism whereby face-specific effects could develop.
The influence of linguistic experience on pitch perception in speech and nonspeech sounds
Authors: Bent Tessa , Bradlow Ann R. , Wright Beverly A.
Published: October 2013

How does native language experience with a tone or nontone language influence pitch perception? To address this question 12 English and 13 Mandarin listeners participated in an experiment involving three tasks: (1) Mandarin tone identification—a clearly linguistic task where a strong effect of language background was expected, (2) pure-tone and pulse-train frequency discrimination—a clearly nonlinguistic auditory discrimination task where no effect of language background was expected, and (3) pitch glide identification—a nonlinguistic auditory categorization task where some effect of language background was expected. As anticipated, Mandarin listeners identified Mandarin tones significantly more accurately than English listeners (Task 1) and the two groups’ pure-tone and pulse-train frequency discrimination thresholds did not differ (Task 2). For pitch glide identification (Task 3), Mandarin listeners made more identification errors: in comparison with English listeners, Mandarin listeners more frequently misidentified falling pitch glides as level, and more often misidentified level pitch ‘‘glides’’ with relatively high frequencies as rising and those with relatively low frequencies as falling. Thus, it appears that the effect of long-term linguistic experience can extend beyond lexical tone category identification in syllables to pitch class identification in certain nonspeech sounds. [Work supported by Sigma Xi and NIH.]
Cue weighting of static and dynamic vowel properties in children versus adults
Authors: Malech Sarah R. , Ohde Ralph N.
Published: October 2013

The purpose of this study was to determine whether children give more perceptual weight than do adults to dynamic spectral cues versus static cues, when identifying vowel sounds. Three experimental stimulus sets were presented, each with 30-ms stimuli. The first consisted of unchanging formant onset frequencies ranging in value from frequencies for [i] to those for [ɑ], corresponding to a bilabial stop consonant. The second two consisted of either an [i] or [ɑ] onset frequency with a 25-ms portion of a formant transition whose trajectory was toward one of a series of target frequencies ranging from those for [i] to those for [ɑ]. Ten children between the ages of 3;8 and 4;1 and a control group of 10 adults identified each stimulus as [bi] or [bɑ]. The results showed developmental effects: the children relied more heavily than the adults did on the static formant onset frequency cue to identify the vowels, while the adults appeared to give more equal weight to both static and dynamic cues than the children did. These findings contradict the Developmental Perceptual Weighting Shift theory and are discussed in relation to this theory and other current research on the development of vowel perception.
Adductor spasmodic dysphonia: Relationships between acoustic indices and perceptual judgments
Authors: Cannito Michael P. , Sapienza Christine M. , Woodson Gayle , Murry Thomas
Published: October 2013

This study investigated relationships between acoustical indices of spasmodic dysphonia and perceptual scaling judgments of voice attributes made by expert listeners. Audio-recordings of The Rainbow Passage were obtained from thirty one speakers with spasmodic dysphonia before and after a BOTOX injection of the vocal folds. Six temporal acoustic measures were obtained across 15 words excerpted from each reading sample, including both frequency of occurrence and percent time for (1) aperiodic phonation, (2) phonation breaks, and (3) fundamental frequency shifts. Visual analog scaling judgments were also obtained from six voice experts using an interactive computer interface to quantify four voice attributes (i.e., overall quality, roughness, brokenness, breathiness) in a carefully psychoacoustically controlled environment, using the same reading passages as stimuli. Number and percent aperiodicity and phonation breaks correlated significanly with perceived overall voice quality, roughness, and brokenness before and after the BOTOX injection. Breathiness was correlated with aperidocity only prior to injection, while roughness also correlated with frequency shifts following injection. Factor analysis reduced perceived attributes to two principal components: glottal squeezing and breathiness. The acoustic measures demonstrated a strong regression relationship with perceived glottal squeezing, but no regression relationship with breathiness was observed. Implications for an analysis of pathologic voices will be discussed.
Time-reversal maximum-length sequence pairs for simultaneous acoustical dual source measurements
Authors: Xiang Ning , Raspet Richard , Dillion Kevin
Published: October 2013

A binary sequence generated by a linear shift-register (maximum-length sequence, M-sequence) and its reversed-order sequence form a time-reversal (reciprocal) M-sequence pair. Their correlation property includes a two-valued pulse-like autocorrelation function and a relatively smaller-valued crosscorrelation function. This unique property, along with other number-theory properties, makes the time-reversal MLS pairs suitable for simultaneous dual source crosscorrelation measurements. In the simultaneous measurement of a dual source system, each of the time-reversal MLS pair simultaneously excites one of two separate sources, one or several receiver signals cross-correlate in turn with each of the MLS pairs resulting in impulse responses associated with two separate sources. The proposed method is particularly valuable for system identification tasks with multiple sound/vibration sources and receivers that have to be accomplished in a limited time period. A fast algorithm: fast MLS transform pair is developed for the crosscorrelation. Its feasibility and potential applications in the acoustical measurements are demonstrated using recent field experimental results.
Modeling and stability analysis of a dynamic system using control theory and signal processing approaches
Authors: Herfat Ali T.
Published: October 2013

Presented in this paper are the following: Analog and digital modeling of a feedback control system; the system stability analysis, using analog and digital methods; and designing the digital system to meet steady-state error and transient response specifications. The digital control systems can control numerous loops at a reduced cost. System modifications can be implemented with software changes rather than hardware changes. Typically, the digital computer is placed in the forward control path, and modeled as a sample and hold network. Digital-to-analog and analog-to-digital converters are required within the system to ensure compatibility of the analog and digital signals. As we proceed with the analysis along with a case study, these criteria will be become apparent in this paper. An industrial dynamic system will be presented as a Dynamic Control System (the case study) in this paper.
Spatio-temporal gradient signal processing for detecting subsurface cracks
Authors: Teramoto Kenbu , Tsuruta Kohsuke
Published: October 2013

This paper presents a crack characterization method by spatio-temporal gradient analysis over the Lamb wave field. The surface ultrasound waves that propagate in the direction of the layer are potential candidates of nondestructive testing (NDT) methodology. The proposed method has an ability to classify the surface acoustic wave field through the rank of the covariance matrix defined over the four-dimensional vector space which is spanned by the following components: a vertical displacement, its vertical velocity, and a pair of shear strains of the surface. The covariance matrix provides the information about cracks. The determinant of the covariance matrix, therefore, is proposed as the index of homogeneity of the object surface. In this study, the computational process in the wave field near the cracks is discussed and their physical meanings are investigated through FDTD-simulations and acoustic experiments.
Simultaneous detection and parameter estimation of multiple nonlinear acoustic chirps
Authors: Dhanoa Jasdeep S. , Hughes Evan J. , Ormondroyd Richard F.
Published: October 2013

Historically, short-time spectral analysis using the Fourier transform and its variants has been the primary method for time-frequency analysis. Recently, Wigner-based methods which provide time-frequency distributions have been applied to linear chirp detection. These methods are limited by the effects of windowing and, for the Wigner methods, cross-spectral components. Furthermore, they do not characterize the signal parameters directly but this may be accomplished by applying a Hough or Radon transform to the time-frequency distribution. For the detection of nonlinear chirps, these methods would be computationally intensive and have low accuracy. This paper introduces a new technique based on evolutionary algorithms for direct detection and parametrization of multiple nonlinear chirps within a window of observation. The optimization of the estimated chirp parameters is done in a nonlinear process using the evolutionary algorithm and the performance of the algorithm is not affected by peak broadening or the cross-spectral components. It exploits the windowing of the finite duration signal and provides higher accuracy even under conditions of high noise. The method also detects pure sinusoids and multiple linear chirps implicitly. The output parameters are, the start and stop frequencies, the phase, amplitude and the coefficients of the nonlinear variation of frequency with time.
Development of an underwater target classifier using target specific features
Authors: Supriya M. H. , Pillai P. R. Saseendran
Published: October 2013

In Sonar, the detection and estimation functions are performed by signal processors, which involve the computation of various statistics, for enhancing the overall performance of the system. This also takes into account all the undesirable propagation effects caused by the underwater channel. Underwater targets can be classified by using certain target specific features such as target strength, target dynamics, and the signatures of the noise generated by the targets. Rough identification of the targets is carried out with target strength values at known aspects while for precise identification, classification clues from target dynamics and target signatures are generated. Databases for the engine noise spectra of various underwater targets, propeller noises, machinery noises and cavitation noises, speed-noise characteristics, etc., have been developed. The signal energy estimated within a finite-time interval is compared with the earlier detection/estimation decisions, which are stored in the target data record and the relevant target data are updated. The algorithm for identification of target from the most matching signature patterns in the database will generate the classification clues, which will help in target identification. Salient highlights of an underwater target classifier using the above-discussed target specific features are presented in this paper.
Some approaches to robust, snapshot-deficient, adaptive processing
Authors: Song Heechun
Published: October 2013

We typically assume that longer arrays and more sensors are always beneficial. However, one of the issues identified by the ONR Ocean Acoustic Observatory Panel was ‘‘snapshot-deficient adaptive processing’’ arising, for example, from the motion of strong interferers (e.g., ships) through the small resolution cells of large arrays. This paper discusses two different but related concepts to reject the moving interferers: (1) null broadening for individual nulling and (2) model-based projection for collective nulling. The plane wave null broadening approach is combined with the robust white noise constraint and extended to matched field processing. The model-based projection exploits the fact that most interferers are close to the surface while targets of interest are usually in the middle of the water column. The projection matrix is constructed from the most significant eigenvectors of a replica covariance matrix from many independent sources within a surface strip. Simulations and experimental data illustrate the techniques.
Interference suppression by tracking and integrating over source motion
Authors: Yang T. C.
Published: October 2013

In this paper, we will show that the beam-domain motion-compensation algorithm can be used to suppress an interference signal when the interference source is at a different bearing/range, and/or has a different bearing/range rate than the signal source. The motion-compensation algorithm was originally developed to preserve the adaptive processing signal gain for a moving source. We have found that it also suppresses interference (beyond normal adaptive processing) under the above-stated conditions. The initial signal bearing is assumed known based on conventional processing but the range is assumed unknown. )The signal is either detected or its presence is highly suggested.) Signal bearing rate and range rate are assumed unknown and will be searched for by the motion compensation algorithm, which yields in principle a highest beam power at the true signal bearing and range rate. We employ an equivalent of a rotating coordinate frame to track the signal bearing-change and use the waveguide invariant theory to compensate the signal range-change by frequency shifting. The mismatch in the bearing and range rate between the interference and signal suppresses the interference power. [Work supported by ONR.]
Nonexhaustive array processing
Authors: Gerstoft Peter , Kim Katherine , Battle David , Kuperman W. A. , Hodgkiss William , Song Heechun
Published: October 2013

Modern arrays may contain of order a thousand elements and the subsequent beamforming requires searching over frequencies, beam angle, source–receiver range, source depth, array depth, array tilt, and array bow. The search space, easily on the order of a trillion cells, suggests seeking alternative approaches to the traditional exhaustive methods. Here we pursue a nonexhaustive global search strategy combined with a local search for significant computational gain. The approach will be illustrated using computationally demanding simulated data and real towed-array data.
The sound of rainfall at sea
Authors: Nystuen Jeffrey A
Published: October 2013

Knowledge of the distribution of oceanic rainfall is needed to more fully describe the marine ecosystem and to provide constraints for climate investigations and for process studies of air–sea interaction. Bubbles generated by raindrop splashes produce a loud and distinctive sound underwater. This sound is a signal that allows the detection and measurement of rainfall at sea. Different raindrop sizes have unique splash characteristics, producing distinctive acoustic signatures for at least four raindrop sizes. These signatures form a mathematical basis for the decomposition of the sound field to measure the drop size distribution in the rain. This information allows the acoustic identification of rainfall type and rainfall rate. The acoustic detection and measurement of rainfall at sea is demonstrated using over 100 buoy-months of data from ocean surface moorings in the tropical Pacific Ocean. This technology is now being transferred to sub-surface instrument platforms. By acoustically monitoring rainfall, and other surface processes including wind speed, from below the surface, many of the fouling, physical damage and vandalism problems that affect surface instruments will be avoided. This technology is passive, introducing no acoustic disturbance into the environment and thus poses no potential harm to marine mammals or other forms of life in the ocean.
Hot topics in underwater acoustics
Authors: Perkins John S.
Published: October 2013

Underwater acoustics is a ‘‘big tent’’ discipline that draws from, and makes contributions to, many diverse fields such as wave propagation, physical oceanography, signal processing and ocean engineering. In recent years, concern for the environmental effects on marine life has spawned research into both the effects of man-made noise, and the use of active and passive acoustics to monitor biological activity. Special Sessions at this meeting reflect this diversity. This paper will draw on these Special Sessions to present some exciting examples of current research: (1) Parabolic equation methods for wave propagation, (2) robust passive sonar techniques, (3) inverse methods for determining geoacoustic parameters, (4) high-frequency acoustic interaction with the sea floor, and (5) bioacoustic resonance. In signal processing, one of the most active areas is the exploitation of the concept of time-reversal. In ocean engineering, there has been a tremendous increase in the applications for autonomous undersea vehicles. A brief overview of developments in these areas will be included. [Work supported by ONR.]
An aeroacoustically driven thermoacoustic heat pump
Authors: Slaton W. V. , Zeegers J. C. H.
Published: October 2013

The mean flow of gas in a pipe past a side branch, closed at the far end, can excite the resonant acoustic modes of the cavity much like blowing across the top of a bottle. This aeroacoustic whistle can excite very high amplitude acoustic waves within the side branch (easily 10% of the mean pressure) at optimal gas flow rates and mean pressures within the main pipe. The aeroacoustic whistle uses no moving parts to convert part of the power in the mean flow into acoustic power. Likewise a thermoacoustic heat pump, utilizing this acoustic power, uses no moving parts to pump heat and establish (or maintain) a temperature difference across a porous medium. This new combination of an aeroacoustic sound source and thermoacoustic heat pump (with suitable thermoelectric elements) is part of an electric power generation feasibility study for natural gas wells. Reliable electrical power generation down-hole to provide electricity for sensors, communications devices or energy storage units is an important research and development goal. Experimental results will be presented that demonstrate the performance of a simple thermoacoustic heat pump when powered by an aeroacoustic sound source. [Work supported by Shell International Exploration and Production B.V.]