bluuebunny/crossref_metadata_2025 huggingface dataset:
On the nature of random system matrices in structural dynamics
Authors: Adhikari Sondipon , Langley Robin S.
Published: February 2014

This work is concerned with the nature of random mass and stiffness matrices arising in linear dynamic systems due to inherent uncertainties in the system parameters. In an important recent paper, Soize [Prob. Eng. Mech. 15, 277–294 (2000)] has developed an expression for the probability density function of such matrices by using the mean value of the matrices in conjunction with the entropy optimization principle. Although mathematically optimal given knowledge of only the mean values of the matrices, it is not entirely clear how well the results obtained will match the statistical properties of a physical system. This issue is investigated here by considering the structure of random matrices arising from Guyan-reduced dynamic models. It is shown that, under rather general conditions, the random parts of the mass and the stiffness matrices of the reduced system in the modal coordinates resemble the so-called ‘‘Gaussian Orthogonal Ensemble (GOE).’’ A single parameter σ (the standard deviation of the matrix diagonals) characterizes a GOE, and this offers the possibility of a very straightforward Monte Carlo simulation technique for the system matrices and response. A limited number of numerical results have been shown in favor of the proposed result.
Electromechanical realization of impedance matrices
Authors: Dupont Pierre E. , Chen Wenyuan
Published: February 2014

Applications exist at both small and large length scales for which one wishes to design an electromechanical system that reproduces a desired impedance matrix. Such a matrix corresponds to one or more degrees of freedom at several attachment points. The design of MEMS filters for signal processing applications is a small length scale example. At a much larger scale, simplified models of dynamically complex machinery are useful for testing the vibration isolation properties of supporting structures. In the first example, the desired impedance matrix is usually defined mathematically while in the latter, a mobility matrix is obtained by experiment. The realization problem is to obtain an electromechanical system that approximates the desired impedance matrix. Constrained approximation is necessary since the literal realization of idealized filters and complex machinery is often precluded by modal complexity, affecting cost and difficulty of construction, and implementation issues, such as nonideal boundary conditions and the lack of ‘‘sky hooks.’’ A two-stage solution to the realization problem is presented that divides the impedance matrix into passive and active components. In the first stage, a reduced-order passive mechanical model is obtained. This model is then modified to incorporate the active behavior. [Work supported by ONR.]
English stress timing and dynamical control of speech timing
Authors: Port Robert , Collins David , Leary Adam , Burleson Deborah , Kitahara Mafuyu
Published: February 2014

Studies of English speech timing have concluded that, despite earlier claims, English is neither stress-timed nor syllable-timed. This study directly measured context effects on timing depending on prosodic neighborhood, and compared the contribution of any stress-timing or syllable-timing tendency while speech cycling. Ss repeated a phrase to a metronome at varying rates. This complex metronome included high-pitched tones (‘beeps’) at roughly 1 s with a lower tone (‘boop’) occurring either 1/2 (2-beat) or 2/3 (3-beat) of the way between beeps. We hypothesize dynamical attractors for stressed syllables at simple harmonic fractions (1/2, 1/3, 2/3) of the phrase cycle. Various texts invite readings with two stresses (‘Bite the back’) or three stresses (‘Bite Bill’s back’), and some had perturbing unstressed syllables inserted between stressed ones (‘Biting Bill’s back’). Perturbing and target vowel onset times were fit with a multiple linear regression equation using time predictions assuming equal stress intervals or equal syllable intervals. The estimated slopes indicate the relative weight of stress versus syllable timing. The weights were greater for stress timing for all subjects, supporting a model of global speech timing where stressed syllable locations have attractors at harmonic fractions, as might be found in a bank of coupled oscillators.
Sentence-final lengthening in connected text
Authors: Smith Caroline L. , Hogan Lisa
Published: February 2014

Lengthening at the end of a prosodic domain is a robust pattern in English, with larger domains characterized by greater amounts of lengthening. Here we investigate whether this pattern extends above the sentence. Is there more sentence-final lengthening at the end of a paragraph than at the end of a paragraph-internal sentence? Ten recordings were made at weekly intervals of an American English speaker reading extracts from a computer manual, which was chosen because such writing has well-defined topic structure. At the same recording sessions, the speaker also read isolated sentences which were constructed so that each word that was sentence final in the connected text occurred sentence medially in one of the sentences, which were designed to match the presence or absence of a pitch accent on the word in the text. Sentence-final lengthening in the text was gauged by comparing a word’s duration in the text to its mean duration across the ten repetitions of the isolated sentences. Very preliminary results suggest that there is more lengthening at the end of a paragraph than in the middle of a paragraph; headings may behave like part of the following paragraph. [Work supported by NSF.]
The influence of speaking rate on spirantization in motor speech disorders
Authors: Turner Greg S.
Published: February 2014

Spirantization occurs often in the speech of individuals with dysarthria. Impairment of muscle movement can lead to an incomplete articulatory obstruction of the vocal tract during the closure period for the production of stop consonants. Air passes through the narrow constriction associated with the incomplete constriction, resulting in the production of fricative noise during the stop gap. This noise leads to the perception of imprecise articulation. It is hypothesized that the speaking rate at which an individual with dysarthria talks will influence the frequency of spirantization. The slower the speaking rate the more time is allowed for the speaker with dysarthria to achieve a tight constriction during the closure period for stop production, resulting in a reduction of spirantization. The opposite would occur for faster rates. For this experiment, individuals with dysarthria read the Farm Passage at three different speaking rates (hab, slow & fast). From this passage, the production of initial voiceless stop consonants (/p, t & k/) were analyzed for the presence of frication during the closure period. Statistical comparisons were made across speaking rate and place of production. group and individual results will be presented.
Extracting tongue muscle contraction patterns from tagged cine MRI
Authors: Stone Maureen , Dick Danielle , Douglas Andrew S. , Shechter Guy , Ozturk Cengizhan , Guttman Michael
Published: February 2014

This study presents mechanically modeled 3-D volumetric strains for the tongue during speech for the syllable ‘‘sha.’’ Multiplanar tagged cine MRI (tMRI) provided input data for a B-spline, geometry-independent, cardiac tag tracking method, devised for the heart, which has been adapted for the tongue. Three sets of tMRI images with orthogonal tag planes were collected in 10 axial and 5 sagittal slices for 24 consecutive time phases. The sagittal slices were recorded twice, once each with a series of horizontal and vertical tag planes. The axial slices were recorded once with lengthwise (anterior-to-posterior) tag planes. These tag planes reflect deformations in the SI, AP, and RL directions, respectively. Within the tongue we tracked 3-D motion, calculated 3-D strains in each image plane, and reconstructed 3-D deformation for the entire volume. From the model muscle contraction patterns are inferred for genioglossus anterior, verticalis, and transverse. To infer muscle contraction we determined the lines of action for each muscle, and tracked their linear strains in the appropriate planes for all 24 time phases. Results showed that muscle compressions are consistent with expected muscle contractions, and we were able to distinguish between transverse and verticalis activity. [Work supported by NIH/NIDCD Grant No. DC01758.]
The phonetics of stress clash in spontaneous speech
Authors: Carmichael Lesley M.
Published: February 2014

This study examines the rhythm rule (RR) in spontaneous speech to determine its acoustic correlates and phonetic robustness in conversational intonation. RR in English is a phonological process that accommodates stress clash. It has been primarily investigated in controlled speech. Both analyses of RR were considered in this study: (1) accent reversal—the relative prominence of key syllables is reversed, (2) accent deletion—the relative prominence of key syllables is neutralized. Two hypotheses were investigated: (1) RR is always indicated by measurable acoustic properties. (2) RR is subject to intonational factors and depends upon the attraction of a pitch accent for realization. Duration, f0, and amplitude were measured on relevant syllables. ToBI labeling was used to indicate pitch accents and phrase boundaries. Duration was the most consistent acoustic cue to stress clash resolution. When the target phrase attracted a pitch accent, duration indicated stress clash resolution by accent reversal. When the target phrase did not attract a pitch accent, f0 and duration indicated accent deletion. Crucially, when the phrases did not attract pitch accents (were not intonationally prominent), stress clash was resolved. This finding provides support for hypothesis (1): RR is pervasive in the acoustic signal independently of intonational factors.
Temporal properties of electromyographic patterns in children’s and adults’ speech
Authors: Kenney Mary K. , Smith Bruce L. , Larson Charles
Published: February 2014

Electromyographic patterns of children’s and adults’ speech production were analyzed to examine temporal relationships among pairs of muscles commonly viewed as functioning either as ‘‘agonists’’ or ‘‘antagonists.’’ It was hypothesized that adults’ greater degree of speech motor control would be evidenced by stronger positive correlations between agonist muscle pairs (e.g., obicularis oris inferior and obicularis oris superior or anterior belly of digastric and depressor labii inferior). In addition, it was expected that greater negative correlations would occur for adults between antagonist pairs (e.g., obicularis oris inferior and depressor labii inferior). A group of adults and three groups of children (5-, 8-, and 11-years old; eight subjects/group) produced multiple repetitions of the phrase, ‘‘Say pap again.’’ EMG activity was measured relative to the two labial consonants in the acoustic waveform, and cross correlations were computed between various muscle pairs. In general, the predicted results were obtained, although negative correlations between antagonist pairs often were not observed. Significant, age-related differences occurred primarily between the adults and the 5-years old, and occasionally between the adults and the 8-years old. The findings suggest that adults tend to have more discrete separation between agonist and antagonist muscle groups in speech production than young children.
Eliciting reduced, citation, and hyperarticulated speech in the laboratory: Acoustic and perceptual analyses
Authors: Harnsberger James D. , Pisoni David B. , Wright Richard
Published: February 2014

A method was developed to elicit sentences in three speech styles (reduced, citation, hyperarticulated) using controlled materials. The reduced style was elicited by having subjects read sentences while, as a distractor task, recalling a digit sequence from short-term memory. In prior work, the digit sequence length was calibrated to the individual subject’s digit span. Using this procedure, a reduced style was elicited from half of the subjects. In this study, the sequence length was set to one additional digit beyond the individual subject’s digit span, in the hope that the more difficult distractor task would consistently elicit a reduced style. The citation style was elicited by having subjects read sentences from a list. The hyperarticulated style was elicited by prompting subjects to reread some sentences again more carefully. Ten subjects were recorded in this experiment. The resulting sentences were acoustically analyzed in terms of sentence duration, keyword duration, and vowel space size. Sentences differing only in style were also presented in a paired comparison test to 35 listeners. The results of both the acoustic analysis and the perception test showed the method was successful in consistently eliciting reduced sentences from 8 subjects, and citation and hyperarticulated sentences from all 10 subjects.
Lingual awareness and the description of isolated syllables of English: A distinctive features analysis
Authors: Lohman Patricia , Fucci Donald
Published: February 2014

The purpose of this investigation was to determine whether normal adult speakers of English could accurately described tongue position within the oral cavity during the production of isolated English syllables. The phonemes were analyzed according to their distinctive features. The effects of training on this task were also examined. Sixty students, 30 majors in speech-language pathology (M age=22.7) and 30 non-majors (M age=18.8) participated in this study. The procedure involved asking participants to (a) imitate the production of a syllable, (b) respond to the question, ‘‘Where was your tongue?’’ and (c) answer four multiple-choice questions regarding tongue height, position, and contact with other structures within the oral cavity. Results indicated that the trained group had higher test scores on all phonemes (p<0.05) with the exception of r and sh (p=>0.05). The Trained group had the lowest scores on the phonemes with the greatest number of features (l=6 features; r,sh=5 features). The Untrained group had the most difficulty describing the phonemes k (3 features), s (5 features), and l (6 features). The results indicated training, as well as type and number of features significantly affected the task.
Modeling and evaluation of coherent equalizer performance in the surf zone environment
Authors: Preisig James C.
Published: February 2014

The environmental conditions encountered in the surf zone give rise to acoustic channel characteristics which can vary significantly. A state space model is developed which describes these characteristics in sufficient accuracy for evaluating their effect on the performance of a coherent acoustic communications system in the surf zone environment. Using techniques developed by the author and presented at the two prior ASA meetings, the impact of the acoustic channel characteristics on coherent communications system performance is analyzed. The theoretical results are compared to experimental data collected at the Scripps Pier during the Fall of 2000 over several regimes of environmental conditions. [Work supported by ONR.]
Statistical characteristics of sound channel in shallow water
Authors: Chen Geng , Chen Yan , Lan Zhang Jian
Published: February 2014

In shallow water under the influence of sea bottom and complicated construction of sound speed profile on sound signal propagation, the system characteristics of channel appear strong time-frequency varied characteristics. In this paper several very efficient measuring methods for obtaining the channel characteristics are developed. For example, a method called pulse-to-pulse correlation is used for measuring long time time-variation characteristics of the sound channel, a linear frequency modulated signal, and a pseudo-random coded signal are used for measuring channel system functions as a response function, transfer function, and scattering function. Among these functions, the scattering function is more important from the point of view of the channel match in under water acoustic signal processing. In this paper, the statistical study of measured scattering functions shows that shallow water sound channel meets the requirement of WSSUS (wide sense stationary uncorrelation scattering) channel. In the case of multipath channel, if the difference of time delays among paths is over the time duration of the code chip, an intersymbol interference will occur. To overcome the ISI a quite simple coherent accumulation of different arriving paths is realized. In the case of shallow water acoustic communication the coherent accumulation shows its efficiency obviously.
Underwater acoustic channel simulator for broadband communication systems
Authors: Kim Byung-Chul , Lu I.-Tai
Published: February 2014

In underwater acoustic (UWA) communications, a reliable numerical simulator is an economical and effective tool for system design and development or for performance prediction and assessment. Some useful channel simulators have been developed in past decades. However, they are only suitable for narrow-band systems, where the channel characteristics are assumed to be the same within the whole signal bandwidth. In order to meet the ever-growing demands of higher and higher data rates for modern UWA communications, the need of broadband simulators is acute. In this paper, a broadband UWA channel simulator is developed, which models UWA channel as a time varying filter with added colored noises. Special emphasis has been given to Doppler effects caused by motion of sensors, platforms and fluctuation of reflecting boundaries. The time varying filter is composed of variable delay generators and amplitude modulators to simulate the Doppler effect for the broadband signal in the UWA channel. By generating a time-varying delay in addition to amplitude variation for each eigenray path, compression and expansion effects of the waveforms and frequency spread are effectively realized. This simulator is employed for designing an orthogonal frequency division multiplexing (OFDM) system in a shallow-water channel.
An experimental study for multilayered building elements with a sub-study on the effect of finite-size test specimens
Authors: Kurra Selma , Arditi David
Published: February 2014

Sound transmission through multilayered building elements was investigated in this experimental study in which sound transmission losses were measured in 28 wall samples with various layer configurations including gypsum board, steel plates, vinyl damping material, glasswool, and airgap. ASTM E90-90 standard was used in the experiment that was conducted at the Riverbank Acoustical Laboratories within a study supported by a grant from IIT/IITRI. The effects of some physical parameters were investigated and comparisons were made in terms of frequency-dependent TL, Rw, and STC values. Test specimens of two sizes (10 m2 and 2.9 m2), were used to derive a size-effect correction which could be used in comparison of measured data and those to be calculated for infinite elements. It was found that the sound insulation values for small-size elements were higher at low frequencies than those of large-size elements, whereas they were lower at mid and high frequencies for both single- and multilayered elements. Statistical analysis indicated that the difference was significant and more emphasized for double gypsum walls with airgaps. Based on the experimental data, variations of transmission loss nd insulation values according to gap width and layer configuration are presented in comparative charts and the results are discussed.
The sound insulation of gypsum board on resilient supports
Authors: Bradley John , Birta Jennifer
Published: February 2014

This work reports on the development of a simple model to explain the effects of adding resilient channels to a rigid double-leaf wall or floor system. The surface layers mounted on resilient channels are treated as a vibration isolator with a fundamental resonance frequency determined by the combination of the stiffness of the resilient channels and the stiffness of the air cavity along with the masses of the surface layers. The effective stiffness of various common forms of resilient channels is determined to be approximately equivalent to that of a 160-mm air cavity. The damping of constructions including resilient channels and cavities with sound-absorbing material is found to vary with cavity depth. The model does not attempt to explain high-frequency transmission through the resilient supports but does permit the optimization of the low-frequency performance of double-leaf constructions with resilient channels. It also demonstrates that the practical range of improvements is limited.
A reduction effect of the floor impact sound after installation of the sound insulation for SMT factory
Authors: Jang Jaehee
Published: February 2014

This study aims to examine some kinds of plans to solve the ploblem of noise and vibration transmitted to adjacent rooms, especially to the downstairs, when using SMT (surface mount technology) equipment. To achive this, a kind of system for preventing noise and vibration was applied, and the effects of sound insulation performance for that were tested and analyzed. To reduce floor impact noise, a floating floor system using a plastic pallet and rubber was applied. The applied plastic pallet is 30 cm wide, 60 cm deep, and 6 cm high and designed to array on a concrete slab. Above this plastic pallet, a 14-cm-thick concrete slab was constructed. After installation of this system the floor impact sound was reduced about 7 dB(A). For more reduction, a ceiling with a 5-cm-thick glass wool and twofold of 0.9-cm-thick plywood was constructed at the directly below downstairs. According to this, 4 dB(A) was additionally reduced.
Directional responses of blueback herring to ultrasonic pulses
Authors: Schilt Carl R. , Escher Charlie , Nestler John M.
Published: February 2014

Adult blueback herring (Alosa aestivalis) have been found to be directionally responsive to very high (118 kHz fundamental) pulsed sounds. The experiments were conducted in a pen containing filtered fresh water. Fish responses were videotaped. Fish usually only flinched in response to the onset of continuous wave stimuli. They usually moved immediately away from the source of short repetitive impulse sounds (duration from around 20 cycles to about four ms and less than 174 dB re 1 mPa at the nearest fish). Although a variety of pulse repetition rates were tested, no clear effect of that variable on fish response was apparent within the limits set by the experimental design. Sounds of similar frequency (120 kHz fundamental, 4 ms pulse duration, 5 Hz repetition rate) but over 200 dB re 1 mPa at the nearest fish also produced a behavioral response which sometimes resulted in the fish moving quickly away from the sound source but always included a dramatic and immediate coalescing into a tight school, as is often seen in the presence of a predation threat. Possible implications for a putative coevolution between Alosine shads and marine mammel predators as well as for ultrasound source localization are discussed.
Duplex auditory distance assessment in a small passerine bird and the relationship with sound attenuation and vocalization production
Authors: Nelson Brian S.
Published: February 2014

Eastern towhees, Pipilo erythrophthalmus (Emberizidae, Passeriformes, Aves) estimate how loudly conspecific vocalizations are produced using correlated spectral and temporal variables and often misjudge speaker distance in the field when vocalization source sound-pressure level (SPL) is varied experimentally. I demonstrate that towhees often misjudge speaker distance when played SPL altered stimuli produced with sound frequencies below 3.5 kHz but rarely misjudge speaker distance when played SPL altered stimuli produced with sound frequencies above 3.5 kHz. I describe the homogeneous physical-acoustic structure of towhee Florida scrub habitat and demonstrate that sound frequencies below 3.5 kHz attenuate more reliably over distance in comparison with sound frequencies above ∼3.5 kHz (i.e., sound frequencies below 3.5 kHz propagate with less variation in attenuation across sites sampled, several speaker and microphone elevations and between days). Lastly, I describe acoustical measurements obtained from calls produced by 52 caged subjects in the field, which suggest that sound frequencies to each side of 3.5 kHz are produced independently or are otherwise emphasized differently during production. These experiments suggest that auditory distance perception in the towhee might be described as ‘‘duplex’’ and that variation in sound propagation might often mediate a close relationship between vocalization production and auditory perception.
The underwater noise of vessels in the Hervey Bay (Queensland) whale watch fleet and its impact on humpback whales
Authors: McCauley Robert D. , Cato Douglas H.
Published: February 2014

In 1994 the underwater noise of 19 vessels involved in whale watching was measured. Vessels ranged from 1.5–70 tons and included yachts, runabouts and high-speed and displacement mono and multihulls. Except for one water-jet trimaran, all vessels were propeller driven. Unlike the directional patterns reported for merchant shipping, each vessel projected lobes of sound fore and aft with lower levels abeam. In the high speed planing vessels this was exacerbated by the deep propellers exposed forward, and the vessel squat while on the plane. All vessels displayed a linear relationship with broadband noise level and the logarithm of speed. Although unique for each vessel, as a rule of thumb doubling the speed doubled the detection range. The response of whales to vessel noise was as much a function of the rate of change of noise as its steady level. Rapid increases in noise produced more responses. Vessels which, by their design, required constant maneuvering to maintain station produced greater adverse responses from whales. Some design criteria important in reducing noise impacts from whale watch vessels include shielding of the propellers in the forward direction, windage in relation to draft, slow speed steerage, machinery noise reduction and passenger viewing access.
Role of high intensity focused ultrasound induced cavitation on platelet aggregation
Authors: Poliachik Sandra L. , Ollos Ryan J. , Crum Lawrence A. , Chandler Wayne L.
Published: February 2014

Our previous studies showed that high-intensity focused ultrasound (HIFU) is capable of producing ‘‘primary acoustic hemostasis’’ in the form of platelet activation, aggregation, and adhesion to a collagen-coated surface. In current studies, 1.1 MHz CW HIFU was used to investigate the role of cavitation as a mechanism for platelet aggregation in samples of platelet rich plasma. A 5 MHz passive cavitation detector was used to monitor cavitation activity, and laser aggregometry was used to measure platelet aggregation. Using spatial average intensities from 0 to 4000 W/cm2, the effects of HIFU induced cavitation on platelet aggregation were investigated by enhancing cavitation activity through use of ultrasound contrast agents, and by limiting cavitation activity through use of an overpressure system. Our results show that increased cavitation activity lowers the intensity threshold to produce platelet aggregation, and decreased cavitation activity in the overpressure system raises the intensity threshold for platelet aggregation. [Research supported by DARPA.]
Laparoscopic partial kidney ablation using high-intensity focused ultrasound
Authors: Tavakkoli Jahangir , Rao Victor V. , Seip Ralf , Sanghvi Narendra T. , Barret Eric , Shalhav Arieh L.
Published: February 2014

A laparoscopic ultrasound probe was developed for image-guided high-intensity focused ultrasound (HIFU) ablation of renal tissue. The probe expands the application of a commercially available HIFU system (SonablateTM) to laparascopic operations. It consists of a 4-MHz focused rectangular HIFU piezoceramic transducer (30×10 mm, FL=30 mm) confocally coupled with a circular central element (8 mm in diameter) used for real-time pulse-echo imaging during treatment. Precise mechanical movements of the transducer enable it to treat targeted tissue volumes. The probe was fully characterized by measuring its electrical impedance, acoustic field, and total acoustic power output. Moreover, the acoustic field was simulated using an analytical model. The laparoscopic probe was able to generate acoustic power levels up to 35 W that correspond to focal intensities over 2200 W/cm2 in tissue, sufficient for tissue ablation through rapid temperature rise (>90°C) and cavitation mechanisms. The probe was tested in an in vivo animal study in which 15 pigs were treated through a sterile laparoscopic procedure. A lesion with dimensions of 23×17×11 mm ±1 mm was successfully generated in the left kidney of each pig during a treatment time of less than 30 min. Histology results demonstrated homogeneous well-delineated lesions generated in the target region.
Design of focused ultrasound phased arrays for prostate treatment
Authors: Tan Joseph S. , Frizzell Leon A. , Sanghvi Narendra T. , Seip Ralf
Published: February 2014

The effect of size and shape of phased arrays for transrectal treatment of the prostate was examined theoretically. The ultrasonic fields were calculated using the point radiator method, including the effects of tissue attenuation. The G parameter, the ratio of intensity at the desired focus to the maximum intensity of any unwanted lobes, was used to compare the performance of various designs. Studies were conducted on spherical segment, cylindrical, and curved cylindrical (cylindrical with curvature added along the length) arrays. The spherical arrays performed well when steered along the array axis (in depth) with G greater than 15 (for an element width of two wavelengths) when steered 15 mm toward the source, but performed poorly when steered along the length of the prostate. The cylindrical array gave the opposite result. The curved cylindrical array yielded performance between the spherical and cylindrical configurations with G greater than 3 (for an element width of two wavelengths) for steering in either direction. With the proper choice of curvature the curved cylindrical array can be designed to provide acceptable performance for steering both in depth and along the length of the prostate. [Work supported by PHS Grant Nos. 5 T32 CA09067 and 1 R43 CA81340.]
Simulation of enhanced absorption in ultrasound thermotherapy due to nonlinear effects
Authors: Liebler Marko , Ginter Siegfried , Dreyer Thomas , Riedlinger Rainer E.
Published: February 2014

Ultrasound thermotherapy (USTT) is used to induce thermal coagulation in human tissue by high intensity focused ultrasound. The absorbed ultrasound energy mainly determines the temperature achieved. It strongly depends on the counteracting processes of nonlinear ultrasound propagation and tissue absorption. To investigate the significance of these different effects for USTT, numerical simulations provide a useful tool for treatment planning. A nonlinear full-wave ultrasound propagation model is presented to simulate USTT. It is based on a high-order FDTD algorithm and combines nonlinear ultrasound propagation with a broadband frequency-power-law absorption. Calculations of temperature distributions are done using Penne’s bioheat-transfer equation. The propagation model is verified by a comparison of measurements and simulations for pressure signals in water and tissue mimicking materials. Simulations with different source signals demonstrate that both higher amplitude and frequency of the source signal amplify nonlinear effects and therefore multiply the enhanced absorbed energy. It is shown that commonly used linear models considerably underestimate the heat generated and are therefore not able to simulate USTT accurately. Furthermore it is demonstrated that optimization of the source signal parameters, like the amplitude and pulse spectrum, could lead to improvement of the therapy by taking advantage of these nonlinear effects.
A broadband Terfenol-D driven flextensional projector
Authors: Porzio Raymond , Carnahan Blake A. , Hussain Aftab , Marietta Martin L.
Published: February 2014

Since 1994 Lockheed Martin has developed a number of Terfenol-D driven Class VII inverse flextensional underwater projectors, known as ‘‘Terfenol Dogbone Flextensional Projectors.’’ The underlying motivation for these projectors has been to match the high-strain, high-energy density, and relatively high-compliance characteristics of magnetostrictive Terfenol-D alloys with the high-compliance characteristics of the dogbone flextensional shell. The resulting projector is reliable, rugged, and has a smaller size, lower-frequency and a broader bandwidth relative to conventional ceramic driven flextensional projectors. The Class VII shell, by virtue of its shape, is designed to naturally accumulate axial compressive stress on the drive assembly with depth. Hence, the dogbone shaped shell is dynamically more compliant to better match the lower modulus of the Terfenol driver. Additionally, both the fundamental bending mode and the second mode of vibration provide dominantly in-phase radiation and well behaved beam patterns. Recently, a small permanent magnet biased projector demonstrated a mechanical quality factor of unity and high source level in its fundamental mode of vibration. A 3-dB band from 2.9 to 6.4 kHz (fundamental mode) and 10 to 18 kHz (second mode) where achieved. The merits, challenge, and future outlook for this technology are discussed. [Work supported by ONR Code 321.]
Performance of a Terfenol-D-driven folded shell projector
Authors: Slaughter Julie , Purcell Christopher
Published: February 2014

The folded shell projector (FSP), U.S. Patent No. 5,805,529, is a compact flextensional transducer originally developed for low-frequency naval sonar applications. The FSP design radiates sound from a one-piece corrugated shell. Because the shell is inherently waterproof, the projector does not need a boot. This reduces cost, improves linearity, increases thermal conductance, and, most importantly, results in stable performance with depth. The folded shell projector is being evaluated for a number of applications including towed array and expendible sonar transducers, community warning sirens, and loudspeakers. A folded shell projector driven by the giant magnetostrictive material, Terfenol-D, has been developed. This transducer was originally designed for use as a community warning siren, however, tests both in air and in water were performed to investigate its response to different acoustic loads. Experimental results of the transducer performance are presented and compared with performance estimates from an equivalent circuit model. Limitations of the current design and the modeling efforts to improve it are discussed as well as plans for future development of the FSP.
Does proximity govern judgments of auditory direction in the azimuthal plane?
Authors: Cohen Annabel J. , Lamothe M. J. Reina , MacIsaac Robert , Fleming Richard , Lamoureux Michael
Published: February 2014

In an experiment analogous to that of Shepard which showed circularity in judgments of relative pitch of pairs of octave-complex tones [Shepard, J. Acoust. Soc. Am. 36, 2346–2353 (1964)], 40 listeners, centered in a sound-attenuated room, judged the apparent direction (clockwise, or counterclockwise) of 396 pairs of successive complex tones emanating from all possible pairs of 12 speakers spaced at 30-degree intervals on an imaginary circumference. Judgments were influenced by speaker proxim-ity and in general mirrored the pattern for judgments of up–down direction associated with the phenomena of circular pitch observed by Shepard. In contrast to Shepard’s pitch judgment task, musical training did not increase sensitivity in the judgment of auditory spatial direction. Unique to the spatial task was the finding that approximately one-half the subjects showed systematic front–back confusion. When this confusion was taken into account, proximity effects were even more apparent. For diametrically opposed speakers (at 180-degrees absent proximity cues), direction was theoretically ambiguous, but listeners showed a small but significant clockwise bias, reminiscent of Deutsch’s tritone paradox for octave-complex tones [Deutsch, Kuyper, and Fisher, Music Percept. 5, 79–92 (1987)]. [Work supported by NSERC.]
The International-INCE Technical Initiatives: An overview
Authors: Daigle Gilles
Published: February 2014

At Inter-Noise 91 in Sydney, Australia, the International Institute of Noise Control Engineering (I-INCE) Board took the first steps to enlarge the scope of the General Assembly’s activities. In particular, the need for technical initiatives to address noise issues of international interest was recognized. Such issues usually involve important policy matters, but the focus is on technical details. The following year in Toronto, Canada, the Board authorized studies on two topics, upper noise limits in working environments and the effect of regulations on road vehicle noise, to be carried out by the General Assembly. Two further initiatives, community noise and noise barriers, were approved in subsequent years. To date, the Technical Initiatives Program has produced two final reports and one draft report. At the 1999 General Assembly in Fort Lauderdale, FL, four new technical initiatives were approved, noise policies and regulations, noise control for schoolrooms, noise from outdoor recreational activities, and noise labels for products. A fifth initiative was added by the General Assembly in Nice, France, on the topic of noise as a global policy issue. This work will give an overview of the objectives and process of the I-INCE Technical Initiatives Program.
Status of the I-INCE technical initiative on noise labels for products
Authors: Hellweg Robert D. , Pope Joseph
Published: February 2014

The I-INCE initiative on Noise Labels for Consumer and Industrial Products is a study of the labeling, and other forms of product information, that deals with noise emissions that are furnished to the purchaser of products. This I-INCE initiative will survey current methods for labeling and otherwise characterizing the noise emissions of such products. (The measurement methods used to test the products will also be included in the survey.) Such labeling methodologies are intended to provide effective means for specifying the noise properties of consumer and industrial products. It is expected that this information will benefit both the users of these products and others exposed to the noise emissions of the products, such as neighbors and bystanders. The methodologies will be compared, and an assessment will be made of their relative effectiveness. An important outcome of this study will be recommendations on how, and in what form, noise labeling can be implemented. The Study Group first met in Nice, France in August 2000. Actions to date and future plans are presented. Opportunities for ASA inputs are described including the status of draft American National Standard on Noise Labeling, currently under ballot by American Standards Committee S12.
Psychometric functions for detection of tones following on- and off-frequency forward maskers
Authors: Schairer Kim S. , Reimer Jason F. , Jesteadt Walt
Published: February 2014

Recent data obtained in our laboratory suggest that the slope of the psychometric function in forward masking can vary widely across conditions, with shallower slopes occurring in conditions with higher signal levels at threshold. The goal of the present study was to separate possible effects of masker frequency, masker level, and signal delay from the effect of signal level per se. Thresholds and psychometric functions were obtained for three normal-hearing listeners using a 2IFC adaptive task. The signal was a 4-kHz, 10-ms tone. The on-frequency masker was a 200-ms tone presented at 30- to 90-dB SPL in 10-dB steps. The off-frequency masker was a 2.4-kHz, 200-ms tone presented at 60- to 90-dB SPL in 10-dB steps. Signal delays were 0, 10, or 30 ms. As expected, forward masking grew more rapidly with increases in masker level in the off-frequency than the on-frequency conditions. Signal delay had little independent effect on the slopes of the psychometric functions. The effects of masker level and signal level were similar for on- and off-frequency masker conditions in most cases. The results will be discussed in the context of a model that incorporates peripheral nonlinearity and internal noise. [Work supported by NIH.]
Intensity discrimination and increment detection in electric hearing
Authors: Wojtczak Magdalena , Donaldson Gail S. , Viemeister Neal F.
Published: February 2014

Intensity DLs were measured in listeners with electric and normal hearing using increments that were gated synchronously with the pedestals and increments whose onsets were delayed relative to the onset of the pedestal (fringe condition). Two biphasic pulse durations (80 and 200 μs/phase) and three increment durations (20, 100, and 500 ms) were used. Normal-hearing listeners were tested with tonal and noise stimuli using an increment duration of 100 ms. It was found that, for short increments, the DLs of cochlear-implant users exhibit a different pattern as a function of pedestal level than the DLs observed for tonal stimuli in acoustic hearing [R. P. Carlyon and B. C. J. Moore, J. Acoust. Soc. Am. 79, 453–460 (1986)]. For longer-duration increments, the ‘‘gated-continuous’’ difference observed in normal hearing for tones and noise stimuli was not consistently observed in electric-hearing data. For cochlear-implant users, intensity DLs measured in the gated versus fringe conditions did not differ substantially for a fringe duration that produced a difference in thresholds of normal-hearing subjects. The possible site of the mechanism mediating the gated-continuous difference in normal hearing will be discussed. [Work supported by NIH Grant P01-DCD00110 and Lions 5M Hearing Foundation.]
Children’s detection of tonal signals in roving level noise maskers
Authors: Allen Prudence , Turpin Suzanne
Published: February 2014

Preschool-aged children’s masked detection thresholds have been measured at S/N levels for which the level of the signal plus masker exceeds that of the masker alone by approximately 6 dB and for which the temporal fine structure of the masked signal approximates that of the signal alone [Allen et al., J. Acoust. Soc. Am. 104, 2997–3005 (1998); P. Allen and L. Korpela, ibid. 105, 1152(A) (1999)]. When level information is removed through randomization of masker levels, children could rely on temporal fine structure changes for detection. This study asked children and adults to detect 500-, 2000-, and 4000-Hz tonal signals presented in roving level maskers centered at 10- or 25-dB N0. Thresholds for some children remained consistent with previous data in fixed-level conditions at all frequencies suggesting that temporal fine structure information may have been used by them, even at frequencies where its coding is subject to phase locking limitations. However, there were large individual differences with many children performing very poorly. [Work supported by NSERC.]
Duration sensation when listening to complex tones
Authors: Kazi Saifuddin , Takaji Matsushima , Yoichi Ando
Published: February 2014

The duration sensation (DS) is defined as one of the primary sensations of the sound signal [Y. Ando, J. Sound Vib. 240(4), to be published on 1 March 2001]. The DS of complex-tone stimuli was examined here by the paired-comparison test while changing the residue pitch or fundamental frequency, i.e., the delay time of the first peak (FP) extracted from the @ autocorrelation function. The white noise was used as a reference and complex tones (two pure-tone components) with three fundamental frequencies, 250, 500 and 1000 Hz, used as test stimuli. Ten subjects judged whether or not the white-noise duration is longer than the complex tone duration under constant 80 dB (A). The rise and fall times defined by the time at a −3 dB drop from the steady level were 1 ms constant. Previous results indicate that the DSs of the pure tone and bandpass-noise stimuli judged longer with the FP longer than that of the stimuli with shorter FP. The purpose of this investigation is to examine whether or not the DS of the fundamental frequency of complex tones is similar to the DS of the pure tone. Experimental results will be presented.
Masking patterns for simple spectral stimuli
Authors: Saoji Aniket , Eddins David A.
Published: February 2014

Auditory processing appears to consist of a series of domain-specific filtering operations that separate complex stimuli into different auditory channels. This begins with tuning in the audio-frequency domain, followed by tuning in the temporal frequency (modulation) domain, and perhaps tuning in the spectral frequency domain. To explore the hypothesis that envelope channels tuned to spectral frequency exist in the auditory system, a masking experiment was designed to measure masking patterns in the spectral domain. Noise carriers with flat spectra were either 1 (800–1600 Hz, 6400–12800 Hz) or 6 octaves wide (200–12800 Hz) and were shaped with sinusoidal spectral envelopes (in cycles per octave). Masker frequencies were 1, 3, or 5 cyc/oct with a spectral contrast of 20 dB. Masked contrast thresholds were measured for signal frequencies ranging from 1.5 octaves below to 2 octaves above the masker frequency. The resulting masking patterns revealed maximum masking at the masker frequency and a gradual decrease in the masking above and below the masker frequency. This tuning is consistent with the assumption of spectral envelope channels tuned to different spectral frequencies. Secondary peaks obtained in several masking patterns may suggest inhibitory interactions among separate spectral channels. [Work supported by NIH NIDCD RO1DC04403.]
David Crighton and the unsteady Kutta condition
Authors: Pierce Allan D.
Published: February 2014

Why do airplanes fly? Because of the Kutta condition. This is a facetious response to the popular explanation (Bernoulli effect) of the lift on an airplane wing. The Kutta condition is that the (inviscid flow) near any distinguished sharp point (such as the trailing edge) should be finite; it invariably requires that the flow further downstream should have a discontinuity in fluid velocity. True potential flows have no discontinuities, but they can have singularities at edges, and result in no lift (d’Alembert’s paradox). Acousticians live comfortably without invoking the Kutta condition when they use Sommerfeld’s theory of the diffraction of sound by a knife edge, but it is invoked without hesitation by most aerodynamicists. Crighton made the distinction of steady versus unsteady flows, acoustic waves being an example of unsteady flows, and wrote an article in 1985 in Annual Reviews of Fluid Mechanics on the Kutta condition in unsteady flow. This summarized and appraised works by himself and others up to that time on when one should preferably use the Kutta condition; the article ends with the optimistic statement that a firm basis existed for understanding the applicability of the condition. The present paper attempts to explain Crighton’s reasoning, but suggests that the subject is still murkily understood.