bluuebunny/crossref_metadata_2025 huggingface dataset:
Anisotropy, range dependence and seismo-acoustic propagation in shallow water.
Authors: Odom Robert I. , Park Jeffrey , Soukup Darin J.
Published: July 2011

The shallow water environment may be highly variable, with both range dependence and anisotropy almost ubiquitous in the seafloor bottom/sub-bottom regions. Some common causes of range dependence include marine-sediment composition, non-planar boundaries, rough surfaces, strong density, or velocity contrasts, and variation in water-column depth and/or sediment-cover thickness. Common causes of elastic anisotropy are compositional layering or vertically aligned cracks. There is an apparent trade-off between anisotropy and range dependence, and difficult to separate the two effects in a propagating signal. If the symmetry axis of a compositionally layered sediment is not exactly normal to the seafloor, the seismo-acoustic wave field has particle-motion polarizations in all three coordinate directions. Even in a one-dimensional medium, an explosion source excites sediment particle motion with all three polarizations. Assuming sediment isotropy when it is not justified can cause errors in layer-thickness computations, elastic property-gradient determinations, acoustic attenuation, and predictions of long-range sound propagation. Employing a modal representation of the seismo-acoustic wavefield, we illustrate the effects of anisotropy and range dependence on the modes, such as mode-identity switching due to angular dispersion and coupling of longitudinal, vertical, and horizontal particle motion polarization. [Work supported by ONR.]
Propagation in a waveguide with range-dependent seabed properties. II: Principles and examples.
Authors: Holland Charles W.
Published: July 2011

A recently derived theory of incoherent propagation in a waveguide with range-dependent boundaries suggests that propagation can often be understood in terms of a few principles. These principles will be reviewed, followed by several examples including fluid and visco-elastic layers that illustrate how a few simple principles can lead to a variety of apparently complex range- and frequency-dependent behaviors. Implications for geoacoustic inversion strategies will also be discussed. In a few instances, propagation over a range-dependent seabed can be calculated using range-independent sediment properties. [Research sponsored by the Office of Naval Research Ocean Acoustics Program.]
Transmission loss tomography of littoral hydrodynamics.
Authors: Yamamoto Tokuo J.
Published: July 2011

Experiments of transmission loss tomography for turbulent and Reynolds stress structures were carried out in Kanmom strait using eight 5.5 kHz source-receiver pairs. The fluid motion within the turbulent current scatters the acoustic wave. The scattered acoustic waves radiate, experience losses due to attenuation and spreading, and are recorded in the form of transmission loss. Because they are small, surface and bottom losses are neglected leaving turbulent scattering and geometric spreading as the dominant transmission losses. Therefore, accurate measurement of transmission loss extracts the scattered acoustic energy losses. Total transmission loss minus spreading loss yields transmission loss (of scattered energy). Transmission loss yields turbulent current motions with the aid of the hydro-acoustics-invariant. From the fluctuations of turbulence on the orthogonal axes, the Reynolds stress tensors are calculated. Reynolds stresses make it possible to calculate the rip currents, upwelling, surf beat, wave surge, sediment transport, and all the elements of littoral hydrodynamics. The imaging of hydrodynamic elements using transmission loss alone is done for the first time.
Manfred Robert Schroeder: A personal memoir.
Authors: D'Antonio Peter
Published: July 2011

This year we are celebrating the 36th anniversary of Schroeder’s seminal paper on sound scattering from maximum length sequences. This paper, along with Schroeder’s subsequent publications on quadratic residue diffusers and other number theoretic sequences, broke new ground, because they contained simple recipes for designing diffusers with known acoustic performance. This presentation will review the impact of Schroeder’s innovation in diffusion on my life, RPG diffusor systems, and the acoustical industry. It will also show how the evolution, design, measurement, prediction, characterization, and optimization of Schroeder’s sound diffusing concepts utilized diverse disciplines, including mathematics and number theory, microwave and crystallographic diffraction, fractal geometry and self-similarity, the Helmholtz–Kirchhoff equation, periodicity and aperiodicity, signal processing, and multi-dimensional optimization. As digital technology has resulted in advances in almost every discipline, Schroeder’s genius gave birth to what I call digital acoustical surfaces, which have found widespread application in every aspect of acoustical architecture. Personally I am indebted to Manfred Schroeder for my career in acoustics and the acoustical community is indebted to him for leading the way and educating all of us with wit, scientific parsimony, and insight.
Schroeder integration: Foundation for advanced sound energy decay analysis.
Authors: Xiang Ning
Published: July 2011

Schroeder’s backward integration method broke the new ground in classical architectural acoustics. Soon after publication of Schroeder’s backward integration method for obtaining sound energy decay functions from room-impulse responses [Schroeder, J. Acoust. Soc. Am. 37, 409–412 (1965)], research activities in this field have been frequently reported in major journal publications. For reverberation time estimation based on a traditional straight-line model, solutions to remedy problems related to the upper limit of backward integration and the background noise in experimentally measured Schroeder decay functions have emerged. Using a parametric model derived from the nature of Schroeder integration, this author proposed a nonlinear regression method [Xiang, J. Acoust. Soc. Am. 98, 2112–2121 (1995)]. The nonlinear regression method yields reverberation time estimates, insensitive to background noise, and the upper limit of integration. Recent interest in acoustically coupled-volume systems has prompted new challenges in analyzing sound energy decay characteristics, which are more complicated than just single-rate decays. This paper will demonstrate a suitable framework for this room-acoustics application using Bayesian inference and the Schroeder backward integration as the foundation of the advanced model-based energy decay analysis. Based on the Schroeder integration, two levels of inference, decay order selection, and decay parameter estimation have been developed for practical applications.
Measurement of impedance at grazing incidence with a standing-wave tube.
Authors: Mellert Volker , Kruse Roland
Published: July 2011

As guest editor of Ando’s book “Concert Hall Acoustics” Schroeder wrote 1985 in his foreword “This lack of low frequencies in the first overhead reflection revealed another low-frequency deficiency that had hitherto gone unnoticed: a progressive attenuation of low frequencies in the direct sound as it grazes across the rows of seats. (This “seat effect” must exist in many other halls, but it is usually masked by the presence of low-frequency components in the early overhead reflections).” Schroeder addressed the acoustics in a famous concert hall. Early digital computing helped to suggest improvements. Even today it remains a problem to exactly determine properties of acoustic material. Determination of the effective impedance of acoustic materials at normal incidence is a standardized procedure (ISO 10534). However, at grazing incidence, the situation is more complicated. Using a modified impedance tube, in which the material under investigation is placed parallel to the direction of wave propagation, and applying Scott’s equation (1946) linking the (complex) wave number in the channel with the properties of the porous material, today’s laptop power can even provide efficient calculations of the impedance at grazing incidence. This paper will also discuss challenges on the uniqueness of the solution.
Musical illusions, absolute pitch, and other enigmas of sound perception.
Authors: Deutsch Diana
Published: July 2011

Several phenomena that were discovered by the author are described, and their implications for music and speech perception are explored. First described is an algorithm for producing circular scales from sequences of single tones, with each tone comprising a full harmonic series. Next discussed are illusions, such as the scale illusion and the glissando illusion, which occur when two streams of sound emanate simultaneously from different regions of space. In several such illusions, a perceptual reorganization occurs, so that a melody formed of tones in one pitch range appears to be coming from one region of space, and another melody, formed of tones in a different pitch range, appears to be coming from the opposite region. Next explored is an illusion in which a spoken phrase comes to be heard as sung rather than spoken, simply by repeating it several times over. Finally, absolute pitch is examined. Although this has been considered a rare faculty, it is shown that speakers of tone language have a very high prevalence of absolute pitch; it is argued that this is due to the association of pitches with meaningful words during the critical period for speech acquisition. The talk is accompanied by sound demonstrations.
The effect of age-related hearing loss on echolocation: Changes in click parameters and echolocation discrimination abilities are initiated by changes in auditory filters.
Authors: Kloepper Laura N. , Nachtigall Paul E. , Breese Marlee
Published: July 2011

High-frequency hearing loss has been correlated with a reduction both in echolocation click parameters and in echolocation discrimination abilities in a false killer whale. During a 15-year time period, the whale demonstrated a significant decrease in peak frequency, center frequency, and source level of outgoing clicks between two studies. Echolocation clicks were analyzed from the most recent phase of the discrimination study to determine if there were significant differences for click parameters according to target condition. The whale consistently produced clicks with the same peak and center frequencies and source levels but varied the number of clicks according to experimental condition. The data suggest that the whale does not use spectral adaptations during discrimination. Likely, a gradual shift in click parameters resulted from a change in the auditory filtering processes initiated with age-related hearing loss.
Disruptive communication: Stealth signaling in the toadfish.
Authors: Mensinger Allen F.
Published: July 2011

Acoustic advertisement signals have evolved in many taxa and are best known among arthropods, anurans, and birds. In populations where individuals alternate signals, males often adjust the timing of calls to avoid overlap. However, specific attempts at jamming especially using a signal that differs temporally and spectrally in fundamental frequency from the advertisement signal appears rare. In the oyster toadfish, Opsanus tau, neighboring males will alternate production of long duration (∼400 ms) advertisement calls or boatwhistles. However, males can also produce short duration grunts (∼100 ms). These grunts are emitted almost exclusively during the boatwhistle of a conspecific male and specifically target the latter portion of the call. The fundamental frequency of the boatwhistle is modified by this disruptive grunt, jamming the signal by lowering its fundamental frequency. The disruptive counterpulse is initiated and completed during the second, tonal portion of the boatwhistle, and its brevity and timing may allow its emitter to remain undetected. The selective forces that are driving the evolution of complex signaling mechanisms remains to be determined; however, it is possible that the alternating boatwhistles evolved as a jamming avoidance function and the disruptive grunts arose to counter this strategy.
Acoustic neural network thermometry in monitoring of thermal therapies.
Authors: Sekins K. Michael
Published: July 2011

The potential benefits of monitoring tissue temperatures and lesioning by “acoustic” methods are evident. Such methods are typically challenging, and limited to interrogating (acoustically) only one or two physical processes during dosing (e.g., sound speed and thermal expansion), which may narrow valid temperature ranges. Due to the complexity of tissue behavior and acoustic interactions during heating, a “gestalt” of acoustic parameters was enabled to be “learned” during dosing by a recurrent neural network (RNN). Using this method, real-time three-dimensional (3-D) acoustic thermometry was demonstrated and (from RNN coefficients) insights were gained into specific acoustic parameter contributions accompanying temperature changes during and after dosing. The RNN method is described for two applications. First, for radiofrequency ablation on excised bovine livers, coregistered B-mode and ARFI elasticity images were acquired. RNN thermometry images were then calculated from rf data, thermal doses calculated, and the necrosis region was then determined, and shown in good agreement with elasticity lesion images. Secondly, HIFU was used to ablate excised bovine liver regions, and the RNN temperatures in tissues were shown to reflect projected power depositions of the HIFU transducer. These results support RNN thermometry as potentially suitable for some thermal therapies. [This research sponsored by U.S. DARPA Contract No. HR0011-08-3-0004.]
Passive mapping for imaging thermal lesions in tissue.
Authors: Jensen Carl R. , Miklós Gyöngy , Ritchie Robert , Coussios Constantin C.
Published: July 2011

Passive acoustic mapping, a method of mapping sources of high-frequency ultrasound emissions during focused ultrasound treatment, has been tested in ex vivo ox liver. The method uses an array of ultrasound sensors placed coaxially with a focused therapeutic ultrasound transducer. The ultrasound emissions received during treatment are first filtered and then beamformed to produce reconstructions of either broadband or harmonic source intensity within the tissue during the application of focused ultrasound. At pressure amplitudes in excess of the inertial cavitation threshold, passive mapping of broadband emissions is found to provide a good indication of the location and size of the lesion, while mapping of harmonic emissions adequately describes the location and onset of boiling. The results for different treatment parameters across several liver samples will be presented. Alternative methods of postprocessing the passively received data for improved spatiotemperoral resolution and signal-to-noise ratio will also be introduced and compared. These methods are being developed to characterize cavitation activity in order to give estimates of cavitation energy, tissue heating, and temperature during therapeutic ultrasound exposures, to ultimately enable prediction of cell death during treatment.
A simple-source model of military jet aircraft noise.
Authors: Morgan Jessica , Gee Kent L. , Neilsen Tracianne , Wall Alan T.
Published: July 2011

Several inverse methods exist to analyze and characterize the turbulence-induced aeroacoustic sources from military jet aircraft. The current study’s purpose is to explore an alternative approach, using a semiempirical equivalent simple source model. The model originated as a single point source located above a hard plane such that the locations of destructive interference from its mirror image matched the measured interference nulls. This appears to provide useful information about the location of the dominant noise source region from the jet. The model has developed into a superposition of Rayleigh-distributed line arrays of uncorrelated and correlated monopoles. The model is tested on an extensive set of acoustic data taken on an F-22 Raptor. Although the model’s line source characteristics are developed using data from only one measurement plane, it is able to accurately reproduce the radiation at other measurement planes. This equivalent line source matches the current prevailing theory that the sideline radiation is largely due to uncorrelated noise whereas the correlated sources dominate downstream. In addition, the semiempirical, simple-source model results corroborate the theory that the peak source location moves upstream with increasing frequency and lower engine conditions.
Calibrating infrasound reference microphones.
Authors: Gabrielson Thomas B. , Marston Timothy M.
Published: July 2011

Low-frequency commercial measurement microphones can be used for infrasound measurement well below their nominal low-frequency roll-off as long as the magnitude and phase of the infrasonic response is known. Three methods are used at Penn State for laboratory measurement of this response: (1) an “absolute calibration” in a piston-driven chamber designed for accurate determination of internal pressure based on piston displacement, (2) a “comparison” calibration in the same chamber where the response is compared to the output of a dc-coupled piezoresistive pressure transducer, and (3) a “hydrostatic” calibration based on the pressure change associated with a sinusoidal variation in elevation. For the first technique, a full thermo-viscous acoustic model for the chamber is used to bridge the adiabatic-to-isothermal transition and to convert piston volume velocity to pressure. The second technique depends on the calibration of the dc-coupled reference transducer. The third technique depends on the elevation-dependence of hydrostatic pressure. The first and second techniques are practical from 0.001 to 25 Hz; the third technique has a smaller practical frequency range—0.05 to 0.5 Hz—but permits an independent check on the other techniques. [Funded by the US Army Space and Missile Defense Command.]
Why bother looking at a range of species?
Authors: Long Glenis R.
Published: July 2011

Most anatomical and physiological researches are conducted on a small subset of mammals, and there are many pressures on auditory researchers to limit their research to a limited number of species with the assumption that this will permit us to explain normal and impaired hearing in humans. Otoacoustic emissions (OAEs) provide a particularly useful comparative tool because very similar measures can be efficiently obtained from a range of species. A full understanding of OAEs in the ear canal can be enhanced when simultaneous measurements are obtained both in the ear canal and within the cochlea. This paper will provide evidence from psychoacoustic, evoked potential and OAE research that comparative research is essential if we are to fully understand human auditory processing.
Comparative cat studies: Are tigers auditory specialists?
Authors: Walsh Edward J. , Armstrong Douglas L. , McGee JoAnn
Published: July 2011

Although representatives of the 41 extant cat species inhabit nearly every biome on the planet and may have faced a highly diverse set of selection pressures during their evolution, relatively little effort has been made to compare commonly measured features of peripheral auditory function among species representing the family. Given their extensive geographic range, it is reasonable to suggest that auditory system adaptations may have occurred, leading to functional specialization in a subset of species. In that light, frequency-threshold curves and response latency-level and latency-frequency relationships will be compared in cats of widely varying body mass inhabiting a variety of habitats. The body mass of felids spans a range of more than two orders of magnitude, with small cats like the desert sandcat, Felis margarita, weighing as little as 2 kg and the Amur tiger, Panthera tigris altaica, weighing as much as 300 kg. While most cats studied thus far appear to satisfy the conditions necessary to be labeled auditory generalists, the tiger, and perhaps members of the Panthera genus generally, may be exceptions. We will consider the possibility that big cats are auditory generalists with regard to acoustic sensitivity, but exhibit a peripheral specialization affecting low-frequency neural latencies. [Funding provided by NSF Grant No. 0823417].
An integrated reception-plate inverse-force structure-borne noise source characterization test method.
Authors: Lai Kevin H.
Published: July 2011

An integrated reception-plate inverse-force method for vibration power and force transmitted from a mounted vibration source measurement has been prototyped and evaluated. The tests developed data to aid in understanding the repeatability and reproducibility of the method, which is necessary as these methods are integrated into industrial noise control design applications. The reception plate has many advantages such as mounting structure mobility matching, simple source-receiver dynamics and inexpensive reproducible test setups. The inverse force method has the advantage estimating of the blocked force characterization in situ. Implementing the inverse method on a reception plate allows the use of a common set of accelerometers measurements. The accelerometers measurements are processed for plate flexural response to estimate input power using reception plate methods and transfer mobility measurements for the blocked force characterization method. The goal of this work is to development of an industrial engineering-tolerance cost-effective, vibration source characterization method for the specification of acceptable source levels of equipment.
Experiences in performing a high-intensity, direct-field acoustic test on a contamination sensitive system.
Authors: Stasiunas Eric C. , Skousen Troy J. , Babuska Vit
Published: July 2011

A direct-field acoustic test (DFAT) was performed on a Sandia system in order to verify survival due to an acoustic environment of 146.7 dB. The DFAT technique—performed by surrounding a test article with a wall of speakers and controlling the acoustic input with a closed-loop control system—was chosen as the test method in order to meet a critical schedule. In choosing this test method, other challenges became apparent, such as how to obtain the high-intensity acoustic levels and what occurs to that environment inside the bagged frame constructed to maintain a contamination-free system. In addition, the vast amounts of data measured during a single test necessitated a way for the test director to quickly visualize the acoustic environment, saving time and provide insight for input adjustments if necessary. Finally, even though the specified acoustic environment was successfully obtained, the results illustrated some drawbacks of the current DFAT method. This paper will detail the DFAT setup used to obtain the test specification, the effects of the contamination frame on the acoustic environment, the quick-look data program created for visual analysis of the acoustic field, and ideas for performing more diffuse DFAT tests in the future.
Radiation loss in Pelamis-like ocean wave energy conversion devices.
Authors: Thiam Amadou G. , Pierce Allan D.
Published: July 2011

At the previous ASA meeting, Peter Rogers suggested that the loss by re-radiation imposes limitations on the energy that can be extracted from incoming ocean waves. In an attempt to answer this question, the authors consider the canonical problem of an infinitely long flexible circular cylinder floating on the surface of an infinitely deep ocean. The cylinder is assumed to be externally forced into heaving oscillations at fixed frequency, and the phasing of the oscillations corresponds to a traveling wave with a fixed wavelength, which is not necessarily the wavelength of the radiated water waves. The entrained mass and the energy radiated per unit length of the cylinder is derived in the low frequency limit by the method of matched asymptotic expansions. The derived analytical results are used in the approximate modification of the multi-degree-of-freedom model of a finite-length multi-segmented cylinder vibrating under the influence of an incoming ocean wave. The influence of radiation losses are significant if the overall length of the device is much greater than the wavelength of the incoming water wave.
Vowel length in Luganda.
Authors: Vogel Irene , Spinu Laura
Published: July 2011

Luganda, a language of Uganda, is like other Bantu languages in exhibiting a contrast between short and long vowels. In many positions, however, this contrast is neutralized, for example, before NC clusters, where it is reported that only long vowels appear. This paper investigates the extent to which such long vowels, which are also nasalized, are similar in duration to contrastively long vowels. Based on recordings of four native speakers of Luganda living in the US (two female), we compare the durations of vowels in the following contexts: (i) vowels before NT and ND clusters (N = nasal, T = voiceless stop, D = voiced stop); (ii) short vowels before T, D, N; and (iii) long vowels before T, D, N. Analysis is in progress and will also examine the acoustic properties of different vowels. Preliminary results show that the overall duration patterns of Luganda are consistent with those reported for several other Bantu languages. That is, vowels are indeed lengthened before NT/ND clusters; however, their average duration is somewhat shorter than that of contrastive long vowels (i.e., V: 149 ms; V before NC: 298 ms; V: 392 ms). Implications for the implementation of the vowel length contrast are discussed.
Aspiration and tone.
Authors: Lai Yuwen , Chen Michi
Published: July 2011

The perturbation effect of prevocalic aspiration on fundamental frequency (F0) was investigated in Mandarin. Previous research has shown conflicting results regarding the effect of aspiration on F0. The present study aims to develop a rigorous experimental design to test possible modulating factors which gave rise to the controversy. Forty minimal pairs contrasting in prevocalic aspiration across three places of articulation from four Mandarin tones were recorded in a carrier sentence. F0 of the following vowel was measured at the onset and every 10% of the tonal contour. Effect of independent variables including aspiration (aspirated and unaspirated prevocalic stops), gender (male and female), and speaking rate (fast and slow) on F0 was evaluated. Preliminary results from 20 native Mandarin speakers (10 females, 10 males) reveal significant main effects of aspiration (higher F0 after aspirated stops), gender (higher F0 in female), and speaking rate (higher F0 in fast mode). More interestingly, interactions of aspiration and gender as well as aspiration and speaking rate are also significant. The effect of aspiration and its interaction with intrinsic F0 of speakers and speaking rate are discussed.
Vowel density differences among regional dialects of American English.
Authors: Fox Robert A. , Jacewicz Ewa
Published: July 2011

Over the past decade there has been considerable interest in differences in the size and shape of vowel spaces across different ages and genders of speakers and across different regional dialects of English. Vowel spaces provide information about the distribution of vowels in the F1 by F2 plane in an individual speaker or group of speakers. Recent studies have investigated which vowels should be used to establish the spatial boundaries and what criteria should be used in drawing the boundaries. However, the weakness of all such approaches is that they do not take into account the number of vowels produced in different portions of the vowel space (the occurrence of a single vowel in a peripheral location is sufficient to enlarge the vowel space). This study proposes to expand and refine the concept of vowel space by creating vowel density maps across different regional dialects of American English. These maps represent a three-dimensional overlay of relative vowel frequencies onto the F1 × F2 plane (the borders of which represent the vowel space). Dialectal differences will be described in terms of differences in the intersection of vowel space areas and differences in vowel density within different portions of the intersected spaces.
Vowel reduction and merger in Pacific Northwest English.
Authors: Wassink Alicia B.
Published: July 2011

The assumption stands in acoustic phonetics that vowel reduction (including undershoot and centralization of short vowels) is greater in casual than controlled speech. However, few studies have investigated the relative magnitude of language-general (phonetic) effects relative to dialect-specific (sociolinguistic) ones. This paper investigates reduction in vowels undergoing sound-change. Pacific Northwestern English (PNWE) /æ/, /ε/ are rising to the spectral location of /ey/, a “merger by approximation” [W. Labov, Princ. Ling. Change, Blackwell (1994)]. Sociolinguistic literature guided selection of two stable/changing pairs (in which one member is stable, the other involved in the merger): /iy ey/, /ɪε/. The normalized corpus (n=1500) was balanced for the following place and voicing and included three conditions (wordlist, reading, and casual). Speakers were partitioned into groups (merged/unmerged). Wassink’s [J. Acoust. Soc. Am. 119, 2334–2350 (2006)] spectral overlap assessment metric was used to detect differences between volumes of vowel ellipsoids (in F1×F2×duration space) and test for style-related spectral shift. Euclidean distances (measured between 20% and 80% timepoints) differentiated vowel trajectories recorded in different conditions. Merged and unmerged speakers’ reduction strategies differed. Merged: expected reduction patterns in both short vowels (including raised /ε/). /y/ trajectories show greater gliding in casual speech. Unmerged: /ε/ does not shift position or trajectory as task changes. [Research supported by National Science Foundation BCS#-0643374.]
Three dimensional digital articulator labeled atlas.
Authors: Murano Emi Z. , Suo Yuanming , Xing Fangxu , Roy Snehashis , Bogovic John , Stone Maureen , Prince Jerry L.
Published: July 2011

There is an increased use of both dynamic and structural magnetic resonance imaging (MRI) methods on studies in normal and disordered speeches. However, due to the anatomical variation among subjects, it has been a challenge to obtain quantitative results from a series of subjects or patients. To compare inter- and intrasubjects’ MRI data a 3-D digital articulator labeled atlas is presented. Experts, head and neck surgeons and speech language pathologists, manually segmented the tongue, soft and hard palate, lips, pharyngeal walls, and larynx from three sets of MRI of healthy volunteers. Then, 30 naïve raters segmented the same articulators with a multiple-structure semiautomated approach for rapid delineation. Concept, application, and comparison with multiple raters and fully manual delineation are provided. [Work supported by NIH-NIDCD Grant No. R00-DC009279.]
Feed-forward control of phonetic gestures in consonant–vowel syllables: Evidence from responses to auditory startle.
Authors: Chiu Chenhao , Stevenson Andrew , Maslovat Dana , Chua Romeo , Gick Bryan , Franks Ian
Published: July 2011

Speech production like other limb movements relies on both feed-forward and feedback mechanisms. Use of a startling auditory stimulus (>90 dB) has been shown to trigger fast, accurate feed-forward performances in upper limb movements prior to access to feedback information [Valls-Solé et al. (1999), J. Physiol. 516: 931–938; Carlsen et al. (2004), J. Mot. Behav. 36: 253–264]. This startle paradigm is applied to test whether pre-programed, feed-forward speech production differs in phonetic detail from production with access to feedback. The experiment examined the production of the CV syllable [ba], starting with the mouth either open or closed. This speech production was triggered either by a control stimulus (82 dB) or by a startling stimulus (124 dB). Results from ten participants showed that lip compression occurred for both starting conditions (mouth open and mouth closed), and also indicated that the timing relationships of the articulators were stable across control trials and startle trials. The acoustics of syllables, formant values, and maximum amplitudes, were consistent across control trials and startle trials, suggesting that the production of pre-programmed gestural configurations in CV syllables may be executed under exclusively feed-forward control.
Are apical trills associated with raised fundamental frequency?
Authors: Trippe Julia E. , Guion-Anderson Susan , Wayland Ratree
Published: July 2011

Previous work has suggested that apical trill production may condition a raised F0, affecting the vowel after onset consonants. This effect has been suggested as the impetus for the reanalysis of a falling-rising tone replacing an onset trill [r] in Khmer [Wayland and Guion, Mon-Khmer Studies 35, 55–82 (2005)]. However, it has not been established whether this increase in F0 is a natural correlate of apical trill production. If so, it should be found in other languages. A raised F0 has been found for trill production in Thai, but preliminary data examining Finnish and Spanish onset trills found no such pattern. Some speakers produced higher F0 after [r] and others did not. The questions of whether there may be aerodynamic constraints associated with trill production that affect F0 or whether language-specific phonetic knowledge, perhaps unconditioned by articulatory constraints, is the source of the F0 patterns are discussed. As part of this discussion, the variation in trills, from multiple cycles to approximate productions, is considered. From a usage-based phonology and sound change perspective, it is questioned how [r] consistently increases F0 to the point of conditioning tonogenesis in one language, but seemingly has no effect on F0 in other languages.
Compression of the acoustic space in intoxicated speech.
Authors: Kaplan Abby
Published: July 2011

Researchers at the phonetics-phonology interface frequently invoke “articulatory effort” to explain the behavior of various speech sounds: less effortful sounds are preferred. However, there is scant empirical basis for most claims about which sounds are the effortful ones. This experiment attempts to observe effort reduction in the laboratory by comparing the speech of sober and intoxicated subjects; there is reason to believe that subjects produce more “easy” sounds when intoxicated than when sober. Subjects produced 264 target words containing intervocalic stops, nasal-stop sequences, and stressed vowels. Acoustic analysis of these productions reveals that subjects’ acoustic space was somewhat smaller in the intoxicated condition than in the sober condition for several measures including stop voicing and intensity; however, no such contraction occurred for vowels. These results have two implications. First, compression of the acoustic space suggests that speech in the intoxicated condition may indeed have been less effortful. Second, the results call into question traditional hypotheses about effort reduction: intervocalic stops moved toward the middle of the VOT continuum, rather than becoming more voiced; vowels, contrary to expectation, did not become more centralized. This study highlights the need for further experimental work on the role of articulatory effort in sound patterns.
Multipulse articulatory modeling in the Wisconsin x-ray microbeam speech production database.
Authors: Katsamanis Athanasios , Bresch Erik , Goldstein Louis , Narayanan Shrikanth
Published: July 2011

Multipulse modeling of articulatory movements can provide a flexible and intuitive representation of the dynamic behavior of speech articulators. Such a representation can prove especially useful for the exploitation of the significant amounts of rich articulatory data that are collected via vocal tract imaging techniques such as real-time MRI or x-ray microbeam. Original multipulse LPC articulatory modeling studies only focused on a limited set of articulations by a single speaker as these were imaged using x-rays. In this work, application of the multipulse modeling framework on the Wisconsin x-ray microbeam speech production database is investigated. This database contains articulatory data, i.e., trajectories of points on the tongue, jaw, and lips during multiple articulations as well as hard palate tracings, from 57 speakers. The original measurements are converted to constriction degree measurements and it is assumed that the corresponding trajectories can be modeled as the output of a low-order linear system when it is excited by a sequence of pulses of variable amplitudes. Pulse locations are determined using optimal matching pursuit and all pulse amplitudes are re-optimized every time a new pulse is introduced. Model similarities and differences are presented both across multiple utterances by the same speaker and across speakers.
Three dimensional parabolic equation modeling of acoustic intensity fluctuations due to internal wave phenomena.
Authors: Dossot Georges A. , Miller James H. , Potty Gopu R. , Smith Kevin B. , Badiey Mohsen , Lynch James F.
Published: July 2011

During the Shallow Water 2006 (SW06) experiment, a J-15 acoustic source deployed from the Research Vessel Sharp transmitted broadband (50–450 Hz) chirp signals 15 km away from a vertical line array. The array was intentionally positioned near the shelf-break front and in an area where internal waves are known to occur. During the same time an internal wave, labeled event 44, passed through the sound field such that the internal wave front was near parallel to the acoustic transmission path. Measured data show substantial intensity fluctuations that vary over time and space due to complex multimode and multipath (both two and three dimensional) interference patterns. This presentation compares three dimensional modeling results using the experimental geometry, acoustic signal parameters, and a simulated oceanographic environment based on environmental moorings and ship-born sensors to mimic the measured internal wave event. A modified version of the three dimensional Monterey–Miami parabolic equation (MMPE) code, which incorporates a user-defined sound speed field, is used. Measured and modeled intensity fluctuations are compared during dominating horizontal regimes such as refraction, focusing, and defocusing. Modal-dependent time-arrival analysis during the different horizontal regimes is examined. A sensitivity study of different sea-bottom properties is explored. [Work sponsored by the Office of Naval Research.]
Nonlinear internal wave parameter influences on energy propagation using radiative transport theory.
Authors: McMahon Kara G. , Lynch James F. , Lin Ying-Tsong , Xiang Ning , Siegmann William L.
Published: July 2011

When two trains of nonlinear internal waves roughly align, their lead waves form effective boundaries of an acoustic duct in which energy is trapped. This type of propagation may be considered a scattering process resulting from the broken internal wave fronts between the lead waves. A traditional approach uses adiabatic normal modes and sound speed perturbations to calculate energy propagation along horizontal rays. An alternate is a radiative transport method in which acoustic vertical modes carry energy and a two-dimensional (2D) transport equation describes horizontal propagation. This model has parameters that are related to waveguide properties and are found from physical internal wave features. One parameter incorporates the significant curvature observed in many internal wave fronts. The two solution approaches are compared and contrasted. Data from the Shallow Water ‘06 Experiment are used to specify internal wave parameters and to compare with model calculations. [Work supported by the ONR.]
On the interaction between acoustic waves and an approaching solitary wave front in waveguides.
Authors: Badiey Mohsen
Published: July 2011

Existence of temperature or density solitary wave fronts in waveguides can change the modal behavior of acoustic wave propagation. When a sound signal travels in horizontal distances, certain source-receiver geometries with respect to the front of a soliton cause multipath intensity interference fringes that are related to the generation of rays in the horizontal plane. Intensity fringes registered at the receiver during these events are due to the interaction of various vertical modes and horizontal rays. The fringe patterns and time-frequency structure, before and after a solitary wave crosses an acoustic track, are shown. Analysis of these fringe structures is discussed using normal mode and PE models. [Work supported by the ONR].
Anthropogenic noise and effects on marine life: A survey of literature and metadata.
Authors: Erbe Christine , Urban Ed
Published: July 2011

The Scientific Committee on Oceanic Research and Partnership for Observation of the Global Oceans have initiated an effort to compile and review the literature on underwater noise with focus on the past 20 years. Literature on anthropogenic noise, ambient noise, and sounds made by marine organisms will be surveyed. Metadata concerning sound profiles of underwater noise sources will also be collected. Results will be made publicly available and links to the original literature and data will be provided where possible. The goal is to provide a baseline of information that can be used as a foundation for new cooperative international research on sound in the ocean as part of an International Quiet Ocean Experiment. An initial synthesis of the literature and any trends in research directions and gaps in research will be presented.
Acoustic radiation during marine pile driving.
Authors: Reinhall Per G. , Dahl Peter H.
Published: July 2011

Pile driving in water produces extremely high sound levels in the surrounding under water environment. Sound levels as high as 220 dB re 1 μPa are not uncommon 10 m away from a steel pile as it is driven into the sediment with an impact hammer. The primary source of underwater sound originating from pile driving is associated with compression of the pile. The pile is struck and the Poisson effect produces a radial displacement motion in the pile that will propagate downward at a computed speed comparable to but less than the longitudinal wave speed in steel. It is shown, using both finite element analysis and modeling based on the parabolic wave equation, that this radial motion of the pile is responsible for the ensuing high underwater sound pressures. It is also shown that the radial motion of the pile is transmitted into the water, either directly from the pile or indirectly via the bottom sediment that is in contact with the pile. A dominant feature of the resulting sound field is an axisymmetric Mach cone with apex traveling along with the pile deformation wave front.
Observations and parabolic wave modeling of underwater pile driving impact noise.
Authors: Dahl Peter H. , Reinhall Per G.
Published: July 2011

Pile driving in water produces extremely high sound levels in both surrounding air and underwater environments. In a companion work [Reinhall and Dahl] it is shown using finite element simulation that for underwater case the primary sound signal originates from a compression wave traveling down the pile at a speed in excess of Mach 3. In this work, we present measurements pile driving impact noise made from a marine construction site in Puget Sound using a vertical line array (VLA) positioned at ranges 8–15 m from full-scale impact pile driving. The measurements are modeled using the parabolic wave equation approach for which synthetic time series are generated (bandwidth 50–2050 Hz). The simulation is achieved by way of a phased array of point sources, representing one source traveling down the pile at supersonic speed. Pile end reflections are included and the process is repeated with both an up- and down-traveling time-delayed sources. With the field computed in this manner, excellent agreement is achieved between model and observations of peak pressure level, and the compression wave speed is also confirmed by way of arrival angle estimation using the VLA. Implications on transmission loss are also discussed. [Work supported by the Washington State Department of Transportation.]
Effect of dredging, traffic, wind, and fish on ambient noise close to the Port of Rotterdam.
Authors: Ainslie Michael A. , de Jong Christ A. F. , Dreschler Jeroen , Wim Groen , van Walree Paul A.
Published: July 2011

Concern exists for possible effects of anthropogenic sound in the sea. Measurements are presented from monitoring of underwater noise associated with dredging activities close to the Port of Rotterdam [http://www.maasvlakte2.com/en/index/]. Measured spectra in the approximate frequency range 30 Hz to 50 kHz are presented in two 1-week average snapshots, one before construction began (September 2008) and the other during construction (September–October 2009). Correlations are described of third-octave band noise level with wind speed on the one hand and with a parameter representing the density of nearby shipping on the other. The correlations are consistent with noise spectra dominated by wind noise at high frequency and shipping traffic noise at low frequency; at intermediate frequencies (roughly in the range 2 to 20 kHz), the sound probably originates from nearby ships with sea surface scattering playing a role in damping the sound in the presence of wind-generated breaking waves and near-surface bubbles. In 2009, a strong correlation between noise level and time of day was observed in the third-octave bands centred at 2.5 and 3.15 kHz with night-time levels exceeding day-time levels by about 10 dB. This day-night difference is attributed to a fish absorption line, possibly due to sprat.
Mitigation of low-frequency underwater sound using large encapsulated bubbles and freely-rising bubble clouds.
Authors: Lee Kevin M. , Hinojosa Kevin T. , Wochner Mark S. , Argo Theodore F. , Wilson Preston S.
Published: July 2011

Low-frequency anthropogenic noise may affect marine life, motivating the need to minimize its potential impact. Bubbles cause significant dispersion and attenuation of underwater sound at frequencies near the individual bubble resonance and can potentially be used to abate this noise. Such effects have been reported for large encapsulated bubbles with resonance frequencies below 100 Hz, and significant attenuation due to bubble resonance phenomena and acoustic impedance mismatch was observed in a tank experiment [J. Acoust. Soc. Am. 127, 2015 (2010); 128, 2279 (2010)]. Both of these mechanisms were found to significantly reduce down-range radiated acoustic pressure, as much as 40 dB, at low frequencies (60 to 1000 Hz) in a series of lake experiments where a sound source was surrounded by an array of tethered resonant toroidal air bubbles, a cloud of freely-rising sub-resonant bubbles, and various combinations of the two. Hydrophones were placed at various depths and ranges to determine the effect of the bubbles on the radiated field. The effects of void fraction and bubble size variation on the spectrum of the radiated sound were also investigated. [Work supported by Shell.]
Following hallowed footsteps and new paths.
Authors: Rosenberg Carl J.
Published: July 2011

Robert Bradford Newman taught architectural acoustics for over 30 years at Harvard and M.I.T. and was a frequent lecturer at numerous other schools. He left an enduring legacy of engaging pedagogy, professionalism, diligence, and wit. He did this in a manner that is remembered still today by former students. This paper acknowledges ways that the legacy has been fostered in on-going courses at M.I.T. (by the author who succeeded Newman at M.I.T.) and elsewhere. A broader view is also addressed with regard to the relationship of architectural acoustics education to developments in building technologies, new trends in engaging students in acoustics, and possible realignment of the process of making architects aware of their professional responsibilities to the aural environment.