bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic evidence for incomplete neutralization of coda obstruents in Korean
Authors: Lee Kyounghee , Bradlow Ann , Goldrick Matt
Published: May 2015

The phonetic manifestation of phonological contrast neutralization is of long-standing interest for our understanding of the phonetic realization of phonological structure. Korean phonology is particularly interesting in this regard with three dimensions of coda contrast neutralization: laryngeal, manner, and palatal. Extending previous work (Kim & Jongman, 1996) that documented complete neutralization of manner contrasts, the present study investigated all of the three types of coda neutralization in both spontaneous (orthography absent) and read speech (orthography present). The results revealed no acoustic differences between most pairs of coda obstruents subject to manner or palatal neutralization. However, laryngeal neutralization was phonetically incomplete with lenis codas (/p, t, k/) differing from their non-lenis counterparts (/pʰ, tʰ, k’/). In spontaneous speech, this was observed in preceding vowel duration, voicing into closure, and closure duration; in read speech, voicing into closure, closure duration, and release burst duration of a following consonant differed. Our new findings demonstrate that laryngeal coda neutralization in Korean is phonetically incomplete regardless of the presence or absence of orthography. As a case of neutralization beyond final devoicing, this study extends the empirical basis of linguistic theory, discriminating between the predictions of traditional theories versus more recent ones such as exemplar-based theory.
Uptalk in Southern Californian English and Mexican Spanish
Authors: Barranco Márquez Karla Y.
Published: May 2015

“Uptalk” is the tendency for declarative sentences to end with rising intonation instead of falling intonation. In Southern Californian English, uptalk is realized with a shallow pitch rise [L-H% in Tones and Break Indices (ToBI) labeling]. In contrast to this are polar questions, which are typically realized with steep rises (H-H%) [Ritchart and Arvaniti 2014]. Uptalk has also been impressionistically found in the variety of Spanish spoken in Mexico City. Mexican Spanish has three forms of phrase-final rises: low-to-high rises (LH%), low-to-mid rises (LM%), and high-to-high rises (HH%) [de-la-Mota et al. 2010], whereas English only has low and high rises [Beckman & Ayers Elam 1997]. Given the larger inventory of possible phrase-final melodies in Spanish vs. English, uptalk may be realized differently in the former than the latter. To determine whether uptalk in Spanish differs from uptalk in English, we analyzed the intonation from one representative female speaker of each language. Fifty phrases from each language were extracted from recordings of two television shows, Laguna Beach (for English) and Rebelde (for Spanish). Two coders then labeled each phrase using ToBI conventions for English and Spanish. The phonological and phonetic differences between English vs. Spanish uptalk will be discussed.
Listener sensitivity to English- and Spanish-specific sounds in a language categorization task
Authors: Blanco Cynthia P. , Bannard Colin , Smiljanic Rajka
Published: May 2015

Listeners are able to distinguish native from non-native speech with as little as 30 ms of input (Flege, 1984; Kondaurova & Francis, 2008), suggesting that listeners’ mental representations include fine-grained acoustic detail about typical and atypical pronunciations in their native language. The current study considers the relative contribution of different language-specific sounds to listeners’ language categorization. English monolinguals and early and late Spanish-English bilinguals categorized nonce words containing a language-specific target segment as belonging to English or Spanish. Target segments included the English phonemes /θ, ɹ/, the Spanish phoneme /r/, and the Spanish and English versions of /l, u/, which exist in both languages but vary in their phonetic implementation. All listeners accurately categorized stimuli with /ɹ, r/ and the Spanish pronunciations of /l, u/. English /θ/ and /l, u/ variants received more mixed responses. For these more difficult sounds, late bilinguals were more accurate than the other groups. Early bilinguals responded faster than the other groups to stimuli with language-specific phonemes, and both bilingual groups responded more quickly than monolinguals to /l, u/. The results reveal that the bilinguals’ experience with both languages enhances their sensitivity to language-specific cues and may lead to more detailed sound representations for their languages.
Word learning by naïve non-native speakers may not be predictable by cognitive test scores
Authors: Shport Irina A.
Published: May 2015

The role of cognitive abilities in learning of words with two types of novel sounds—lexical tones and coronal consonants—was compared. Individual differences were expected to play a larger role in implicit learning of tones than consonants. Twenty-two English speakers took tests assessing working memory, attention, executive function, and processing speed (NIH & Northwestern University, 2006–2012, NIH Toolbox: Cognition). Then, they learned twelve Vietnamese words varying in their initial consonants [m, t, ʈ, ʐ] and tones (high level, falling, and rising). After training with feedback, the learning was assessed in a 12-word alternative identification test (N = 792). The range of accuracy scores was 11.1–80.6%, with the mean accuracy of 43.6% (SD = 18.5). The proportion of tonal errors was significantly larger than the proportion of consonantal errors [χ(1) = 174.68, p < 0.001]. Mixed-effect regression analyses showed, however, that cognitive test scores did not explain the variance in the word identification accuracy. These results suggests that although lexical tones are more challenging than consonants for speakers of non-tone languages, adult beginning learners may be able to learn words with different types of novel sounds equally efficiently, regardless of individual differences in cognitive abilities.
Audience design in non-native speech
Authors: Conklin Jenna T. , Kentner Ashley , Law Wai Ling , Lin Mengxi , Wang Yuanyuan , Dmitrieva Olga
Published: May 2015

Speech has been shown to accommodate the communicative needs of listeners, for example, for increased intelligibility compared to normal speech. Previous research shows that native speakers adapt their speech in the presence of noise (Garnier et al., 2006), and when addressing children (Biersack et al., 2005) or foreigners (Scarborough et al., 2007). However, our knowledge of how non-native speakers modify their speech depending on the interlocutor is limited. The goal of this study is to identify acoustic features of non-native speech, which may be affected by a change in listener characteristics, particularly, in terms of language background. Native speakers of Mandarin from the same dialectal area gave directions in a map task to three confederate participants: another native speaker of Mandarin (a non-native speaker from the same L1 background), a native speaker of English (a native speaker of participants’ L2), and a native speaker of Russian (a non-native speaker from a different L1 background). Acoustic variables associated with audience design in speech, including measures of speech rate, pitch, vowel duration, vowel quality, and vowel space were examined and compared to results of a detailed survey of participants’ language experience and attitudes toward their first and second languages.
Contributions of practice with feedback and testing without feedback to learning of a non-native phonetic contrast
Authors: Wright Beverly A. , LeBlanc Emma K. , Conderman Jessica S. , Coburn Courtney S.
Published: May 2015

Listeners learn non-native phonetic contrasts given practice and feedback, but what is the dose-response curve for that training? Does testing without feedback affect that response? We trained native English speakers on a non-native phonetic contrast between pre-voicing and voicing on two consecutive days, varying the number of daily training trials across groups. Practice with feedback for 240, 120, or 60 trials/day all led to a similar steepening of the category-boundary slope, but practice with feedback for 30 trials/day yielded no learning. To determine whether the daily pre- and post-training tests without feedback (120 trials/test) affected this outcome, we trained another group 60 trials/day with feedback, but removed all but the final post-test. This group did not learn, indicating the tests without feedback facilitated improvement. Finally, to establish whether the benefit from these tests came from task performance, we trained another group 60 trials/day with feedback, but replaced the original tests with stimulus exposure alone until the final post-test. This group’s ending performance resembled that obtained with task performance during the tests without feedback. Thus, trials with feedback can function as an all-or-none trigger for recruiting the contribution of trials without feedback, or mere stimulus exposures, to speech learning. [NIH supported.]
Asymmetries in the perception of Mandarin tones: Evidence from mismatch negativity
Authors: Politzer-Ahles Stephen , Schluter Kevin
Published: May 2015

The mismatch negativity (MMN) component of the electroencephalogram reflects phonological asymmetries: specifically, greater MMN is elicited by infrequent (deviant) tokens when the features of the frequent (standard) token are phonologically underspecified than when those features are phonologically fully specified. Such asymmetries have not been studied in non-Indo-European languages or in suprasegmental contrasts, which might not be represented in the same way as segments. Therefore, the present study investigated the neural representation of Mandarin contour tones. Mandarin third tone (T3) is realized as second tone (T2) in certain contexts, whereas it has no alternation relationship with fourth tone (T4). The present study examined MMNs elicited by T3~T2, T3~T4, and T2~T4 contrasts (in both directions). Asymmetrical MMN effects were elicited in both T3~T2 and T3~T4 contrasts: MMN was smallest when the standard was T3. The results suggest that T3 has a less specified neural representation than both T2, which it alternates with, and T4, which it does not. This may be due to the featural representation of T3 (in standard Mandarin it is a Low tone, which is typologically less marked) or due to its behavior (i.e., it may be the case that features which alternate always trigger reduced MMN effects).
Incidental auditory category learning
Authors: Holt Lori L. , Gabay Yafit , Dick Frederic , Zevin Jason
Published: May 2015

Little is known about how auditory categories are learned incidentally—that is, in the absence of overt category decisions or experimenter-provided feedback. This is an important gap, as learning in the natural environment does not arise from explicit feedback and there is evidence that the learning systems engaged by traditional tasks are distinct from those recruited by incidental category learning. We examined incidental auditory category learning with a novel paradigm, the Systematic Multimodal Associations Reaction Time (SMART) task, where participants rapidly detect and report the appearance of a visual target in one of four possible screen locations. Although the overt task is rapid visual detection, a brief sequence of sounds precedes each visual target. These sounds are drawn from one of four distinct sound categories that predict the location of the upcoming visual target. These many-to-one auditory-to-visuomotor correspondences support incidental auditory category learning. Participants incidentally learn categories of complex acoustic exemplars and generalize this learning to novel exemplars and tasks. Further, learning is facilitated when category exemplar variability is more tightly coupled to the visuomotor associations than when the same stimulus variability is experienced across trials. We relate these findings to theories of incidental phonetic category learning.
Azimuth-elevation direction finding using one four-component acoustic vector-sensor spread spatially along a straight line
Authors: SONG Yang , Wong Kainam T.
Published: May 2015

A considerable literature has developed to use the four-component acoustic vector-sensor to estimate the azimuth-elevation direction-of-arrival of incident acoustic sources. A four-component acoustic vector sensor (a.k.a. a “vector hydrophone” in underwater applications) consists of a pressure sensor, plus three identical but perpendicular univariate velocity-sensors, which are often idealized as collocated. One shortcoming of the above acoustic vector sensor is the point-size of its array aperture, due to the spatial collocation of all its four component-sensors. If these four component-sensors are placed at different spatial locations, there would arise spatial phase factors among these component-sensors’ data, and the array-manifold of (1) would be invalid, thus the incident wavefield’s propagation direction is no longer so straight-forwardly obtainable. However, Song & Wong (JASA 4, 2013) shows that how the four component-sensors may be allowed to spread out arbitrarily in three-dimensional space (thus sampling the incident wavefield at different locations), while not just achieving direction finding, but to do so with increased accuracy. This paper will focus on one particular array grid to spread out the four component-sensors—on a straight line in any permutation.
Compressive beamforming with LASSO
Authors: Gerstoft Peter , Xenaki Angelliki
Published: May 2015

For a given sound field observed on an array, compressive beamforming reconstructs the direction-of-arrival (DOA) map using a sparsity constraint on the source distribution. The problem is posed as an underdetermined problem expressing the pressure at each receiver as a superposition of plane waves associated with each DOA, a phase delayed sum of source amplitudes. The L1 sparsity constraint makes the problem solvable with convex optimization and the sparsity constraint gives improved resolution. We here derive the sparse source distribution using maximum a posteriori (MAP) estimates for both single and multiple snapshots. Compressive beamforming does not rely on any matrix inversion and thus works well even for single snapshots where it gives higher resolution than conventional beamforming. For multiple snapshots in a free-space environment, compressive beamforming has a performance similar to MVDR. In a multi-path environment MVDR fails, but compressive beamforming works well. The superior resolution of compressive beamforming is demonstrated with vertical array data from event S5 in the SWellEx96 experiment in a multi-path shallow water environment.
Laboratory measurements of sound propagation in a continuously stratified ocean containing internal waves
Authors: Zhang Likun , Swinney Harry L. , Lin Ying-Tsong
Published: May 2015

A tank experiment is being conducted to explore sound propagation in a continuously stratified ocean containing internal gravity waves that produce fluctuations in acoustic signals. The tank is filled with water of increasing salinity with increasing depth in the fluid; the variation in salinity results in a 150 m/s variation of the sound speed over the 50 cm-depth fluid. Sound arrival times determined in three-dimensional hydrophone scans map out the sound diffraction pattern in the stratified fluid. Good agreement is found between the measurements and results obtained from wavefront modeling by ray acoustics. Sound fluctuations produced by internal waves are measured for several acoustic track locations and at different phases of the internal waves that radiate from a mechanical wave generator. Internal wave fields measured by particle image velocimetry provide input for a parabolic equation model, which is used to predict the sound fluctuations for comparison with measurements. This research is designed to improve the understanding and modeling of sound propagation and scattering by internal waves in the realistic oceans. [Research support: The 2013-14 ASA F. V. Hunt Postdoctoral Research Fellowship (L. Zhang) and ONR MURI Grant N000141110701 (WHOI).]
Influence of short time scale water column fluctuations on broadband signal intensity and beam spreading
Authors: Eickmeier Justin , Badiey Mohsen
Published: May 2015

The environment in a recent experiment exhibited short time scale isotherm depressions and elevations in the temperature profile of the water column. This dynamic behavior is significantly pronounced over a 2 hour period (between 70–90 m depth) during a 24 hour deployment. High frequency broadband transmissions (22–28 kHz) were sent between a stationary source (5 m above the seafloor) and an 8-element vertical hydrophone array (4.5 m above the seafloor) in an approximate depth of 100 m with 1 km separation. Vertical beamforming of measured impulse response across all array elements and application of Gaussian steering revealed strong correlation between vertical temperature profiles and angular spread of the direct path receptions. Inherently a 3D problem, we consider a 2D approach to show beam fluctuations as a function of the environment. 2D PE modeling is driven by measured sound speed profiles to calculate the acoustic field between source and receiver and to beamform across an ideal vertical array for data/model comparison. Over time, fluctuations in the intensity of the acoustic beam, spatial path and angular spread of the direct path signal can be attributed to the vertical oscillations of isotherms in the water column. [Work supported by ONR321.]
An assessment of the effective density fluid model for scattering from poroelastic sediments with inclusions
Authors: Bonomo Anthony L. , Chotiros Nicholas P. , Isakson Marcia J.
Published: May 2015

The effective density fluid model (EDFM) was developed to approximate the behavior of sediments governed by Biot’s theory of poroelasticity. Previously, it has been shown that the EDFM predicts reflection coefficients and backscattering strengths that are in close agreement with those of the full Biot model for the case of a homogeneous poroelastic half-space. However, it has not yet been determined to what extent the EDFM can be used in place of the full Biot model for other cases. In this work, the finite element method is used to compare the scattered pressure predicted using the EDFM with the predictions of the full Biot model for the case of a poroelastic half-space with a single inclusion. The geometry is assumed axisymmetric and the inclusions are allowed to be either a fluid or an elastic solid. [Work supported by ONR, Ocean Acoustics.]
An investigation into the acoustics of different sized open plan and enclosed Kindergarten classrooms
Authors: Mealings Kiri T. , Buchholz Jörg M. , Demuth Katherine , Dillon Harvey
Published: May 2015

Open plan classrooms, where several class bases share the same space, have recently re-emerged in Australian primary schools. This study compared the acoustics of four different Kindergarten classrooms: an enclosed classroom with 25 students, a double classroom with 44 students, a linear fully open plan triple classroom with 91 students, and a semi-open plan K-6 classroom with 205 students. Ambient noise levels, intrusive noise levels, occupied background noise levels, and teacher’s speech levels were recorded during different activities. Room impulse responses using logarithmic sweeps were also recorded for different teaching scenarios. From these recordings, signal-to-noise ratios, speech transmission index scores, and reverberation times were calculated. The results revealed much higher intrusive noise levels in the two largest open plan classrooms, resulting in signal-to-noise ratios and speech transmission index scores to be well below those recommended in classrooms with students of this age. Additionally, occupied background noise levels in all classrooms were well above recommended levels. These results suggest students may have difficulty listening and learning in open plan classrooms and teachers are likely to strain their voice. Therefore, open plan classrooms are unlikely to be appropriate learning environments for young children unless high intrusive noise levels are moderated.
Sound levels and speech privacy in an open space academic learning environment
Authors: Ruhala Richard J. , Baker Aaron , Shpuza Ermal
Published: May 2015

Undesired sound and speech privacy in a large educational space or open office environment are persistent problems for occupants. The architectural design studio on the campus of Kennesaw State University (formerly Southern Polytechnic State University) is used as a case study. Students have desk space very similar to those in professional open offices, and are used for individual and group projects. Simultaneously classes are held where instructors or students will be presenting to their class in an area that is only partially partitioned off from the rest of the design studio. For the first set of in situ experiments, sound levels are recorded over several days at various locations and correlated with learning activity. Second, broadband noise is used to measure the reduction of spectrum levels between source and receiver, at different locations. Finally, students and professors participate in an anonymous questionnaire regarding their perceptions of the acoustic quality of the space; specifically regarding the speech intelligibility of professors, level of noise distractions, and preferences of when to work in the studio. This study aims to understand the acoustic impact of human activity occurring concurrently in a large open academic environment.
Minimum phase acoustic systems: An intuitive model study
Authors: Hashemgeloogerdi Sahar , Bocko Mark F.
Published: May 2015

The zeros and poles of minimum phase systems lie within the unit circle in the z-plane, which ensures the existence of a stable inverse. In acoustics, the question if a system is minimum phase has important consequences, such as the ability to find an inverse of a room’s acoustic transfer function to compensate for reverberation. In this paper, we provide an intuitive model of minimum phase acoustic systems based upon physical arguments. Using the image method, we compute the transfer function of generic one, two, and three-dimensional acoustic enclosures with a sound source and a microphone placed at arbitrary locations. We find the relationship between the direct sound field and the reverberant sound field that ensures the minimum phase property of the system. Essentially, the system retains the minimum phase property if the radius of reverberation, i.e., the distance from the source where the direct sound and reverberant sound become equal in magnitude, lies outside of the boundaries of acoustic enclosure. We show that a one-dimensional acoustic system always is minimum phase for the entire range of source-microphone locations and wall reflection coefficients. However, two and three-dimensional enclosures display minimum phase response for limited ranges of the system parameters.
The use of acoustic playbacks with captive cetaceans
Authors: Bruck Jason N.
Published: May 2015

Playbacks are a powerful tool in studies of animal communication and cognition. They can provide insights into referentiality, social memory, anti-predator strategies, sexual selection, as well as a host of other topics. In particular, playbacks have been a useful method for understanding the nature of wild dolphin communication using temporarily restrained animals. Unfortunately, there are a series of questions where complete social histories of subjects or certain controls are needed, but unavailable in wild study populations. Captive, free-swimming animals present a complementary set of subjects where one can address questions involving referentiality or dolphin social memory. Methods for conducting playbacks with captive groups differ greatly than for wild subjects. I will explore the procedural differences of these experiments, including overcoming difficulties associated with recording and presenting sounds in an acoustically challenging environment as well as how to measure response behavior. Furthermore, I will discuss the potential of captive acoustic playbacks by highlighting data collected from such studies including evidence for dolphin multi-decade social memory, context dependent cue usage and acoustic kin recognition.
Molecular imaging using ultrasound and microbubbles
Authors: Villanueva Flordeliza S.
Published: May 2015

Increasing insight into the molecular mechanisms of disease has created a need to visualize sub-cellular events in clinical populations in order for treatment paradigms to advance. Molecular imaging has emerged as an important translational tool for understanding disease pathogenesis, for which various probes and detection methods have been developed. Ultrasonic detection of molecular markers of disease using acoustically active particles is one such in vivo modality. Molecular imaging with ultrasound utilizes intravascular delivery of gas-filled microspheres (microbubbles) targeted to bind to disease-specific epitopes expressed by vascular endothelial cells. Microbubble binding occurs by virtue of targeting ligands attached to the microbubble surface, which confer specific binding to the endothelial target. In the presence of ultrasound, the bound microbubbles emit an acoustic signal which can be detected as a persistent contrast effect during ultrasound imaging with non-linear based detection strategies. In pre-clinical models, ultrasound molecular imaging has been used to detect early atherosclerotic disease, myocardial ischemic memory (recent myocardial ischemia), acute heart transplant rejection, angiogenesis, and for in vivo tracking of therapeutically administered stem cells. Such applications raise exciting possibilities for meaningful bedside translation of this imaging platform to address important clinical issues in an era of molecular medicine.
Molecular imaging with ultrasound: Steps toward clinical translation
Authors: Willmann Juergen K.
Published: May 2015

Molecular imaging provides the ability to non-invasively assess expression levels of molecules by measuring imaging signals generated with the help of molecularly targeted contrast agents. These contrast agents can be directed to bind various molecular targets, thereby visualizing and quantifying disease processes at the molecular level in vivo. In recent years, the field of molecular imaging has been rapidly expanding and involves multiple imaging modalities. Among those, ultrasound imaging is a widely available, relatively inexpensive, and real-time imaging technique without exposing patients to radiation. It is already the first-line radiological imaging modality for many organs and disease processes in patients. By combining the these advantages of ultrasound with the ability to image molecular signatures using novel molecularly targeted ultrasound contrast agents, molecular ultrasound imaging is a quickly evolving imaging strategy that has great potential as a highly accurate and quantitative method for various clinical applications, including earlier detection of for example cancer, characterization of focal lesions, and quantitative monitoring of various disease processes at the molecular level. The objective of this presentation is to provide an overview on the principles of ultrasound molecular imaging and to highlight current translational studies to move ultrasound molecular imaging approaches into first in human clinical applications.
Laser-induced vaporization and acoustic-induced cavitation of droplets
Authors: Yu Jaesok , Nguyen Man M. , Kim Kang
Published: May 2015

In this study, micro-droplets developed for photoacoustic imaging and drug delivery have been evaluated in vitro. Induced by a short laser pulse, perfluoropentane mixed with optical dye was vaporized and expanded up to about 20 times of initial diameter of 3–10 micron, generating strong broadband photoacoustic signals. It was found these vaporized droplets became less stable and prone to rupture to ultrasound pulses. The broadband inertial cavitation signals by a very short ultrasound pulse can provide high spatial resolution in passive cavitation imaging. For feasibility test, passive cavitation imaging algorithms were implemented in a commercial ultrasound open platform with a linear array transducer, centered at 5 MHz. The system was synchronized with a 1 MHz unfocused single element transducer. 700kPa single-cycle excitation ultrasound pulse was induced to a 580 μm inner diameter polyethylene tube containing micro-droplets. The cavitation imaging was performed before and after vaporizing droplets by laser. Broadband emissions of 3–7MHz were observed only with vaporized droplets. These preliminary results show the feasibility of cavitation imaging of vaporized droplets with a short ultrasound excitation pulse for improved spatial resolution and could lead to further in-vivo experiments.
A sum-of-harmonics time-domain method to distinguish harmonic and broadband signals during passive acoustic mapping of ultrasound therapies
Authors: Lyka Erasmia , Coviello Christian , Kozick Richard , Coussios Constantin C.
Published: May 2015

Passive Acoustic Mapping (PAM), a novel technique for real-time monitoring of ultrasound-based therapies, performs passive beamforming of nonlinear acoustic emissions simultaneously received on an array of transducers. These emissions can be classified according to their frequency content into harmonic, indicative of nonlinear scattering, stable cavitation or tissue boiling, and broadband, indicative of inertial cavitation. However, the magnitude of coherent reflections often greatly exceeds that of incoherent broadband emissions arising from inertial cavitation and the ability to distinguish these two components is, thus, key to successful detection and mapping of inertial cavitation. We propose a novel time-domain-based filter that uses a parametric model in order to estimate a time-varying amplitude harmonic component in the presence of a lower-amplitude broadband signal. Performance evaluation on simulated and experimental data has shown that the model is able to accurately detect a time-varying amplitude harmonic signal for harmonic-to-broadband amplitude ratio as high as 20 dB, even in short data lengths, decreasing the estimation error by at least 80% compared to conventional comb filtering, and it yields passive acoustic maps of better accuracy and spatial resolution. Sum-of-harmonics is expected to become a valuable component of real-time PAM and significantly contribute toward its clinical adoption.
A nonlinear derating method for estimating high-intensity focal pressures in tissue
Authors: Dibaji Seyed Ahmad Reza , Liu Yunbo , Soneson Joshua E. , Banerjee Rupak K. , Myers Matthew R.
Published: May 2015

Methods for converting high-intensity focused ultrasound (HIFU) pressure measurements made in water to values appropriate for tissue have considerable value in preclinical testing and treatment planning. Such “derating” methods are straightforward in the linear-acoustics regime, but are much more difficult at higher powers. In this study, a nonlinear derating method is used to estimate focal pressure in a tissue phantom. The on-axis pressure in water was recorded using a hydrophone. Fourier transformation of the recorded pressures was performed and the resulting modal amplitudes were reduced using a combination of “source scaling” (measurements in water performed at a lower source pressure than in tissue phantom) and “endpoint scaling” (amplitudes reduced at the target location). The reduced modal amplitudes were used in the convolution term of the evolution equation to determine the pressure in tissue. The focal pressure waveform estimated by this method was compared with a direct measurement in a tissue phantom. The results show that, with the proper combination of source and endpoint scaling, focal pressure in a tissue phantom can be reproduced by derating within 15% error.
Aerodynamic and acoustic analysis of an industrial fan
Authors: Liu Yi , Bain Jeremy , Wang Gang , Lucas Mike , Wang Percy
Published: May 2015

The efforts to predict noise radiation for an industrial fan using direct computational fluid dynamics (CFD) simulation is presented in this paper. Industry has been using CFD tool to guide fan design in terms of efficiency prediction and improvement. However, the use of CFD tool for aero-dynamic noise prediction is very limited in the past, partly due to the fact that research in aero-acoustics field was not practical for industry application. With the most recent technologies in CFD field, the industry application of aero-acoustics becomes much more promising. It is demonstrated here that fan tonal noise and broadband noise at low frequencies can be predicted using Overset grid system and high order finite difference schemes with acceptable fidelity.
Initial laboratory experiments to validate a phase and gradient estimator method for the calculation of acoustic intensity
Authors: Torrie Darren K. , Whiting Eric B. , Gee Kent L. , Neilsen Tracianne B.
Published: May 2015

A recently developed phase and gradient estimator (PAGE) method for calculating acoustic intensity from multiple pressure measurements [Thomas et al., J. Acoust. Soc. Am. 134, 4058 (2013)] has been tested via anechoic laboratory measurements of the radiation from multiple loudspeakers. The measurements were used to examine the effects of probe geometry, size, frequency range, and source characteristics on the active intensity calculated from both the PAGE and the traditional cross-spectral approaches. Preliminary results are shown for multiple probe and source configurations, and confirm that the PAGE method results in a broader valid frequency range for a given probe geometry.
Unconditionally stable time-domain elastic wave simulations by the alternative direction implicit method
Authors: Shao Yu , An Myoung , Wang Shumin
Published: May 2015

The stability of the conventional staggered-grid finite-difference time-domain (FDTD) method for elastic wave simulations is limited by the Courant condition and material heterogeneity. Its computational efficiency is significantly hampered when the mesh size is much smaller than a wavelength (for geometric modeling accuracy) and/or with a high impedance contrast. An unconditionally stable alternating direction implicit (ADI) method is proposed to overcome the conditional stability. It is based on additively splitting the Crank Nicholson (CN) operator into two sub-operators and subsequently solving the CN scheme in two sub-steps. In each sub-step, a tri-diagonal matrix is formed based on one of the sub-operators and the associated field variables are solved implicitly with O(N) computational complexity. The rest of the field variables are solved explicitly. Due to its semi-implicit nature, it can be proved that the ADI method is unconditionally stable regardless of the time step size. The numerical dispersion properties of the ADI method are also analyzed theoretically. Several numerical examples of acoustic wave scattering from elastic targets are further provided to demonstrate its accuracy and efficiency.
Movable optical lens array using acoustic radiation force
Authors: Koyama Daisuke , Kashihara Yuta , Hatanaka Megumi , Nakamura Kentaro , Matsukawa Mami
Published: May 2015

A movable optical lens array that utilizes acoustic radiation force was investigated. The lens array consists of a rectangular glass plate, two piezoelectric bimorph transducers, and a transparent viscoelastic gel film. By electrically exciting the transducers, the flexural vibration mode was generated along the glass plate. The acoustic radiation force acts to the surface of the gel so that the surface profile can be deformed and the lens array can be fabricated. A cylindrical lens array with the lens pitch of 4.6 mm was fabricated at 113 kHz. The lens positions correspond with the loop positions of the flexural standing wave, and the lens pitch corresponds with half the wavelength of the flexural vibration of the glass plate. The focal points of the lens could be changed by the input voltage, and the lens can act as a variable-focus lens. The lens positions could be moved in the length direction by two-phase drive. The moving distance of the lens was 4.6 mm when the driving phase difference between the two transducers changed from 0 to 360°. The translation of the lens array was applied as an optical scanner.
Thermoacoustic energy harvesting
Authors: Avent Andrew W. , Bowen Christopher R.
Published: May 2015

Thermoacoustics have a key role to play in energy harvesting systems, exploiting a temperature gradient to produce powerful acoustic pressure waves. As the name suggests, thermoacoustics is a blend of two distinct disciplines: thermodynamics and acoustics. The field encompasses the complex thermo-fluid processes associated with the compression and rarefaction of a working gas as an acoustic wave propagates through closely stacked plates in the regenerator of a thermoacoustic device; and the acoustic network that controls the phasing and properties of that wave. Key performance parameters and appropriate figures of merit for thermoacoustic devices are presented with particular emphasis upon the critical temperature gradient required to initiate the acoustic wave and the thermal properties of the key component, namely, the “stack” or “regenerator". Mechanisms for coupling a thermoacoustic prime mover with electromagnetic harvesters and piezoelectric transducer materials are also presented, which offer the potential to enhance the energy density attained beyond that possible with linear alternators. Numerical modeling strategies are presented, which enable parametric sweeps of the geometric and thermal properties, which influence the efficiency, and performance of the key components of such devices. Potential coupling and non-linear effects are examined.
Fabrication of micro-lens array using surface acoustic wave
Authors: Taniguchi Satoki , Takayanagi Shinji , Koyama Daisuke , Nakamura Kentaro , Matsukawa Mami
Published: May 2015

A technique to form an optical micro-lens array using surface acoustic wave (SAW) was investigated. The lens has no mechanical moving parts, such as gearing systems, and is composed of a simple structure. A viscoelastic transparent silicone gel film with the thickness of 20 μm was formed on a 128°-rotated Y-cut X-propagation LiNbO3 (LN) substrate between two interdigitated transducers (IDTs). The IDT electrodes consisted of 30 finger pairs with the aperture length of 9.1 mm and the periodic pitch of 200 μm were fabricated on the LN substrate. The IDTs was excited with a continuous sine wave with the amplitude of 0 to 15 Vpp at the resonance frequency (20 MHz) to generate the SAW. The leaky SAW propagated into the gel, and the acoustic radiation force acted to the surface of the gel film so that the surface profile of the gel could change and a micro-lens array could be fabricated on the gel. The lens height could be controlled by varying the voltage applied to the IDTs.
Measurement and analysis of musical vibrato parameters
Authors: Zhang Mingfeng , Bocko Mark , Beauchamp James W.
Published: May 2015

Vibrato is a fundamental feature of many musical sounds, with vocal, stringed instrument, and many wind instrumental performances employing vibrato as a principal device for conveying musical expression. In this paper, we describe a signal processing toolbox for extracting and analyzing vibrato-related parameters from audio recordings. In our method, sonic partials of a musical sound are separated first, followed by tracking of the instantaneous amplitude and frequency of each partial. A number of parameters that characterize vibrato can then be extracted from the tracked partials; these include the common frequency of the amplitude modulation (AM) and the frequency modulation (FM), the modulation depths, the relative phase between the AM and FM components of each partial, and the harmonic contents of the modulation components. This then enables a detailed comparison of the vibrato of various musical sounds, for example the relative amounts of AM and FM, the rate of vibrato, the correlation and phase between AM and FM vibrato components, and many other features. This framework provides a useful tool for applications such as music performance pedagogy and musicological studies.
Real-time visualization of musical vibrato for music pedagogy
Authors: Zhang Minhao , Zhang Mingfeng , Smith Sarah , Bocko Mark
Published: May 2015

Vibrato is a fundamental expressive attribute in music, especially in singing, in stringed instrument performance, and in the performance techniques of many wind instruments. Performers typically invest a great deal of time and practice to gain adequate control of vibrato in performance To assist and accelerate this learning process we are developing computer based vibrato visualization tools. In this paper, we present a low-latency, near real-time system that enables performers to visualize their vibrato. The system employs a video-game-like visualization scheme to display the instantaneous AM/FM trajectories of a musical sound, either by itself or in comparison to pre-recorded target sounds, to enable the user to attempt to match the vibrato trajectory of an existing performance. In addition to demonstrating the system, feedback from music students and studies of the effectiveness of the system will be presented.
Estimation of a violin source/filter model
Authors: Beauchamp James W. , Vijayakumar Ashwin K.
Published: May 2015

The source/filter model is often mentioned in the acoustics and signal processing literature (e.g., Gold and Morgan, Speech and Audio Signal Processing, Wiley) but has seldom been implemented for musical instrument sounds. An exception was by Mathews and Kohut, (“Electronic simulation of violin resonances,” J. Acoust. Soc. Am. 53(6) (1973)). In this study, we attempt to separate source harmonic amplitudes from a violin filter characteristic using harmonic tracking analysis of glide tones performed in an anechoic chamber. Assuming that the violin bridge/body constitutes a linear system, if string force harmonics are constant over pitch, they should sweep out frequency responses that only differ by constant amplitude ratios over their overlap regions. Departures from constant ratio behavior can be interpreted in terms of source spectra that change with fundamental frequency. Interpretation and detailed results of this analysis are given.
The influence of sung vowels on pitch perception
Authors: Devaney Johanna , Richardson Derek
Published: May 2015

Phonologists have demonstrated that in speech there is an intrinsic pitch of vowels, i.e., that different pitch heights are perceived for different spoken vowels with the same mean fundamental frequency. Only limited work has been done on the impact of sung vowels on perceived pitch and previous studies, using forced choice paradigms, have found conflicting results comparing Front/Close to Back/Open vowels: Ternstrom, Sundberg, and Colldén (1988), using manipulated sung tones, found that Front/Close vowels were perceived as higher than other vowels while Fowler and Brown (1997), using synthesized tones, found that Front/Close was perceived lower than Back/Open. The current study uses a method-of-adjustment paradigm to examine pitch perception of all four extremal vowels: Front/Close (/i/), Front/Open (/æ/), Back/Close (/u/), and Back/Open (/ɑ/), using completely controlled, but realistic synthesis. It also assesses whether different models of pitch perception are necessary for the various vowel types. In the experiment, the subjects are asked to match a reference tone that has no formants against a stimulus tone with first and second formants corresponding to a particular vowel. Both the reference and stimulus tones are identical in their synthesis except for the formants and are 300 ms in length.
Differentiated electroglottograph and audio signal measurements of vocal fold closed quotient during a register change: Single note data
Authors: Morris Richard J. , Okerlund David , Bernadin Shonda
Published: May 2015

Recently, the use of the differentiated electroglottograph (dEGG) signal combined with a differentiated audio (dAudio) signal was reported as a means for more reliable measurement of the closing quotient (CQ) from the EGG signal in combination with a time synchronized audio signal. The purpose of this study is to combine CQ data with resonance data from the vocal tract during a register shift. Files recorded from group of 15 trained females provided the data. The singers were directed to shift between chest and mixed registers while sustaining a note that could be sung comfortably in both registers. An EGG and an audio signal were recorded. These signals were time aligned, and the EGG, dEGG, and dAudio were displayed. These three signals were used to determine the CQ and peak resonant amplitude before and after the register shift. Preliminary results indicate that the singers maintained a similar CQ measurement across the register shift. In addition, the preliminary data indicate that the singers changed the dominant harmonic in the sung note when they changed registers. That is, they maintained the same fundamental frequency but altered the resonance of the tone in the vocal tract.
The interaction between infrasonic waves and gravity waves perturbations: Application to explosions at the Utah test and training range
Authors: Lalande Jean-Marie , Waxler Roger
Published: May 2015

Infrasonic waves propagate at long range through atmospheric ducts resulting from the stratification of atmospheric properties. These ducts are characterized by their spatio-temporal variability. Hence, infrasonic waves integrate information upon the atmosphere along their propagation paths. In order to study infrasonic wave propagation, we resort to atmospheric specification combining numerical weather prediction and climatological models. However, due to the lack of observations these models fail to describe small scale variability such as perturbations associated to the presence of internal gravity waves. These waves play an important role in the atmospheric dynamic by transferring momentum to the mean flow at critical levels and at wave-breaking altitudes. In this study, we intend to describe the interaction of infrasonic waves with internal gravity waves in order to understand the long-tail behavior observed in infrasound broadband signals. We developed a model for the propagation of internal waves used to generate realistic perturbations of the background atmospheric states. By using a linear full-wave model of infrasound propagation, our goal is to ultimately relate infrasound characteristics to internal waves properties. We apply those numerical models to infrasound observations recorded during the 2010 deployment of the Utah Test and Training Range (UTTR) experiment.
On atmospheric updating, attenuation, and thermospheric phases in infrasonic wave-trains
Authors: Waxler Roger M. , Assink Jelle , Lonzaga Joel
Published: May 2015

Because of the dramatic increase in temperature in the thermosphere, thermospheric phases are ubiquitous, despite the fact that they are less often detected than are stratospheric phases. In the thermosphere, the density of the atmosphere is very low so that, as a propagation medium, the thermosphere is very non-linear and very attenuating. Atmospheric specifications of the lower thermosphere are not well constrained by data. This can lead to significant errors in modeling propagation along thermospheric paths. Methods for generating corrections to specifications of the thermosphere from infrasonic data are described. Further, using a non-linear ray theory model we find that non-linear effects in the thermosphere, in particular, period lengthening, mitigate against attenuation. Finally, we show that it is possible to use thermospheric returns to simultaneously update the atmospheric specifications while determining source yield.